objective-c : Intermediate Text Kit (master-detail book app for ipad)

Intermediate Text Kit (master-detail book app for ipad).m

//Intermediate Text Kit (master-detail book app for ipad)

//1. basic UI

//AppDelete.h

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

@end


//AppDelegate.m

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{   
    UISplitViewController *splitViewController = (UISplitViewController *)self.window.rootViewController;
    UINavigationController *navigationController = [splitViewController.viewControllers lastObject];
    splitViewController.delegate = (id)navigationController.topViewController
    return YES;
}

@end


//ChaptersViewController.h (MasterViewController)

@class BookViewController;

@interface ChaptersViewController : UITableViewController

@property (strong, nonatomic) BookViewController *bookViewController;

@end


//ChaptersViewController.m

#import "BookViewController.h"

@implementation ChaptersViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.bookViewController = (BookViewController *)[[self.splitViewController.viewControllers lastObject] topViewController];
}


#pragma mark - Table View delegate method

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return 0;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell" forIndexPath:indexPath];

    return cell;
}

@end


//BookViewController.h (DetailViewController)

@interface BookViewController : UIViewController <UISplitViewControllerDelegate>

@end


//BookViewController.m

@interface BookViewController ()

@property (strong, nonatomic) UIPopoverController *masterPopoverController;

@end

@implementation BookViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    self.view.backgroundColor = [UIColor colorWithWhite:0.87f alpha:1.0f];
    
}


#pragma mark - Split view

- (void)splitViewController:(UISplitViewController *)splitController willHideViewController:(UIViewController *)viewController withBarButtonItem:(UIBarButtonItem *)barButtonItem forPopoverController:(UIPopoverController *)popoverController
{
    barButtonItem.title = @"Chapters";
    [self.navigationItem setLeftBarButtonItem:barButtonItem animated:YES];
    self.masterPopoverController = popoverController;
}


- (void)splitViewController:(UISplitViewController *)splitController willShowViewController:(UIViewController *)viewController invalidatingBarButtonItem:(UIBarButtonItem *)barButtonItem
{
    // Called when the view is shown again in the split view, invalidating the button and popover controller.
    [self.navigationItem setLeftBarButtonItem:nil animated:YES];
    self.masterPopoverController = nil;
}

@end



//2. Rendering the text

//AppDelegate.h

@interface AppDelegate : UIResponder <UIApplicationDelegate>

//...
@property (nonatomic, copy) NSAttributedString *bookMarkup; //store the book markup file and formatting in an attributed string

@end


//AppDelegate.m

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{   
    //...
    NSString *path = [[NSBundle mainBundle] pathForResource:@"alices_adventures"
                                                     ofType:@"md"];
    NSString *text = [NSString stringWithContentsOfFile:path
                                               encoding:NSUTF8StringEncoding error:NULL];
    self.bookMarkup = [[NSAttributedString alloc] initWithString:text];
    
    return YES;
}


//Create a new BookView class, subclass of UIView, will be used to render the book text

//BookView.h

@interface BookView : UIView

@property (nonatomic, copy) NSAttributedString *bookMarkup; //stores the text to be rendered

- (void)buildFrames; //creates the Text Kit components required for rendering

@end


//BookView.m

@implementation BookView
{
    //layout manager: transforming the characters in text storage
    //into rendered characters (i.e. glyphs) on screen.
    NSLayoutManager *_layoutManager;
}


//creates a UITextView with a custom “Text Kit stack”
//consisting of an NSTextStorage, NSLayoutManager, and NSTextContainer
- (void)buildFrames {
    
    // create the text storage
    NSTextStorage *textStorage = [[NSTextStorage alloc] initWithAttributedString:self.bookMarkup];
    
    // create the layout manager
    _layoutManager = [[NSLayoutManager alloc] init];
    [textStorage addLayoutManager:_layoutManager];
    
    // create a container
    NSTextContainer *textContainer = [[NSTextContainer alloc] initWithSize:CGSizeMake(self.bounds.size.width, FLT_MAX)];
    [_layoutManager addTextContainer:textContainer];
    
    // create a view
    UITextView *textView = [[UITextView alloc] initWithFrame:self.bounds
                                               textContainer:textContainer];
    
    textView.scrollEnabled = YES;
    [self addSubview:textView];
}

@end


//BookViewController.m

//import header
#import "BookView.h"
#import "AppDelegate.h"

//add a new instance variable

@implementation BookViewController
{
    BookView *_bookView; //keep track of an instance of BookView
}


//replace viewDidLoad with the following implementation

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    self.view.backgroundColor = [UIColor colorWithWhite:0.87f alpha:1.0f];
    
    //sets the edges for extended layout, so that the view doesn’t appear under the navigation bar
    [self setEdgesForExtendedLayout:UIRectEdgeNone];
    
    AppDelegate *appDelegate = (AppDelegate *) [[UIApplication sharedApplication] delegate];
    
    _bookView = [[BookView alloc] initWithFrame:self.view.bounds];
    _bookView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
    
    _bookView.bookMarkup = appDelegate.bookMarkup; //assigns the markup loaded by the app delegate to _bookView's bookMarkup property
    
    [self.view addSubview:_bookView];
}


//add the following code just below the viewDidLoad


- (void)viewDidLayoutSubviews
{
    [_bookView buildFrames];
}



//3. Adding a multi-column layout

//change BookView's superclass from UIView to UIScrollView

//BookView.h

#import <UIKit/UIKit.h>

@interface BookView : UIScrollView

//...

@end


//BookView.m

- (void)buildFrames {
    
    // create the text storage
    NSTextStorage *textStorage = [[NSTextStorage alloc] initWithAttributedString:self.bookMarkup];
    
    // create the layout manager
    _layoutManager = [[NSLayoutManager alloc] init];
    [textStorage addLayoutManager:_layoutManager];
    
    // build the frames
    NSRange range = NSMakeRange(0, 0); // NSUInteger loc, NSUInteger len
    NSUInteger containerIndex = 0;
    
    while(NSMaxRange(range) < _layoutManager.numberOfGlyphs) {
        
        // 1. Create a frame for the view at index
        CGRect textViewRect = [self frameForViewAtIndex:containerIndex]; //윈도우의 1/2 사이즈 뷰 rect 생성
        
        // 2. Create an instance of NSTextContainer
        //UITextView adds an 8.0f margin above and below the container
        CGSize containerSize = CGSizeMake(textViewRect.size.width, textViewRect.size.height - 16.0f);
        NSTextContainer* textContainer = [[NSTextContainer alloc] initWithSize:containerSize];
        [_layoutManager addTextContainer:textContainer];
        
        // 3. Create the UITextView
        UITextView *textView = [[UITextView alloc] initWithFrame:textViewRect
                                                   textContainer:textContainer];
        [self addSubview:textView];
        
        containerIndex++;
        
        // 4. Determine the glyph range for the new text container
        range = [_layoutManager glyphRangeForTextContainer:textContainer]; //returns the range of glyphs laid out in the given text container. used to determine whether further text containers are required.
    }
    
    // 5. Update the size of the scroll view
    self.contentSize = CGSizeMake((self.bounds.size.width / 2) * (CGFloat)containerIndex, self.bounds.size.height);
    
    self.pagingEnabled = YES;
}



//compute the frame size for each textView : frame to be a column of half the width of the screen, reduces the margins a bit
//then sets the position to be the proper amount from the left of the view based on which column it is

- (CGRect)frameForViewAtIndex:(NSUInteger)index {
    
    CGRect textViewRect = CGRectMake(0, 0, self.bounds.size.width / 2, self.bounds.size.height);
    textViewRect = CGRectInset(textViewRect, 10.0, 20.0); // CGRect rect, CGFloat dx, CGFloat dy
    textViewRect = CGRectOffset(textViewRect, (self.bounds.size.width / 2) * (CGFloat)index, 0.0);
    
    return textViewRect;
}



//4. Adding text styling

//apply some appropriate styling to the Markdown formatting

//Create a new class. Name the class MarkdownParser, make it a subclass of NSObject

//MarkdownParser.h

@interface MarkdownParser : NSObject

- (NSAttributedString *)parseMarkdownFile:(NSString *)path;

@end


//MarkdownParser.m

@implementation MarkdownParser
{
    //for storing the various text attributes that are applied to the text in order to style it.
    NSDictionary *_bodyTextAttributes;
    NSDictionary *_headingOneAttributes;
    NSDictionary *_headingTwoAttributes;
    NSDictionary *_headingThreeAttributes;
}


- (id) init
{
    if (self = [super init]) {
        [self createTextAttributes]; }
    return self;
}


- (void)createTextAttributes
{
    // 1. Create the font descriptors (UIFontDescriptor describe a font with a dictionary of attributes)
    //Create two font descriptors for the Baskerville family: one normal, and one bold
    UIFontDescriptor *baskerville = [UIFontDescriptor
                                     fontDescriptorWithFontAttributes: @{UIFontDescriptorFamilyAttribute: @"Baskerville"}];
    
    UIFontDescriptor *baskervilleBold = [baskerville
                                         fontDescriptorWithSymbolicTraits:UIFontDescriptorTraitBold];
    
    // 2. determine the current text size preference (user’s text size preferences without using the default font)
    UIFontDescriptor *bodyFont = [UIFontDescriptor preferredFontDescriptorWithTextStyle:UIFontTextStyleBody];
    NSNumber *bodyFontSize = bodyFont.fontAttributes[UIFontDescriptorSizeAttribute];
    CGFloat bodyFontSizeValue = [bodyFontSize floatValue];
    
    // 3. create the attributes for the various styles (using Baskerville font and various multiplications of the user’s preferred body text size)
    _bodyTextAttributes = [self attributesWithDescriptor:baskerville size:bodyFontSizeValue];
    _headingOneAttributes = [self attributesWithDescriptor:baskervilleBold size:bodyFontSizeValue * 2.0f];
    _headingTwoAttributes = [self attributesWithDescriptor:baskervilleBold size:bodyFontSizeValue * 1.8f];
    _headingThreeAttributes = [self attributesWithDescriptor:baskervilleBold size:bodyFontSizeValue * 1.4f];
}


//creates a dictionary with a single font attribute

- (NSDictionary *)attributesWithDescriptor: (UIFontDescriptor*)descriptor size:(CGFloat)size
{
    UIFont *font = [UIFont fontWithDescriptor:descriptor size:size]; //returns a font matching the given font descriptor
    return @{NSFontAttributeName: font};
}



- (NSAttributedString *)parseMarkdownFile:(NSString *)path
{
    NSMutableAttributedString* parsedOutput = [[NSMutableAttributedString alloc] init];
    
    // 1. break the file into lines and iterate over each line
    NSString *text = [NSString stringWithContentsOfFile:path encoding:NSUTF8StringEncoding error:nil];
    
    //componentsSeparatedByCharactersInSet: split the text into an array of individual lines.
    NSArray *lines = [text componentsSeparatedByCharactersInSet:[NSCharacterSet newlineCharacterSet]];
    
    for(NSUInteger lineIndex=0; lineIndex < lines.count; lineIndex++)
    {
        NSString *line = lines[lineIndex];
        
        if ([line isEqualToString:@""])
            continue;
        
        // 2. match the various 'heading' styles
        NSDictionary *textAttributes = _bodyTextAttributes;
        
        if (line.length > 3) {
            
            if ([[line substringToIndex:3] isEqualToString:@"###"]) {
                textAttributes = _headingThreeAttributes;
                line = [line substringFromIndex:3];
                
            } else if ([[line substringToIndex:2] isEqualToString:@"##"]) {
                textAttributes = _headingTwoAttributes;
                line = [line substringFromIndex:2];
            
            } else if ([[line substringToIndex:1] isEqualToString:@"#"]) {
                textAttributes = _headingOneAttributes;
                line = [line substringFromIndex:1];
            }
        }
        
        // 3. apply the attributes to line of text determined in step 2.
        NSAttributedString *attributedText = [[NSAttributedString alloc] initWithString:line
                                                                             attributes:textAttributes];
        // 4. each complete line of text is appended to the output
        [parsedOutput appendAttributedString:attributedText];
        [parsedOutput appendAttributedString:[[NSAttributedString alloc] initWithString:@"\n\n"]];
    }
    
    return parsedOutput;
}


//AppDelegate.m

//add the following import

#import "MarkdownParser.h"

@implementation AppDelegate


//in didFinishLaunchingWithOptions: method, replace with the following code

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{   
    //...
    
//    NSString *path = [[NSBundle mainBundle] pathForResource:@"alices_adventures"
//                                                     ofType:@"md"];
//    NSString *text = [NSString stringWithContentsOfFile:path
//                                               encoding:NSUTF8StringEncoding error:NULL];
//    self.bookMarkup = [[NSAttributedString alloc] initWithString:text];
    
    //replace above code
    NSString* path = [[NSBundle mainBundle] pathForResource:@"alices_adventures" 

ofType:@"md"];
    MarkdownParser* parser = [[MarkdownParser alloc] init];
    self.bookMarkup = [parser parseMarkdownFile:path];
    
    return YES;
}

@end



//5. Performance improvements
//preloads the left and right scroll views before the user actually scrolls the view, rather than preloads all views

//BookViewController.m

//log message to figure out how much app consumes memory and CPU

- (void)viewDidLoad
{
    //...
    //log message to figure out how much app consumes memory and CPU
    //see the time differences between viewDidLoad and viewDidAppear
    //alse memory usage (almost 100mb)
    NSLog(@"viewDidLoad");
}


- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    
    NSLog(@"viewDidAppear");
}


//remove the following lines of code from the buildFrames method

- (void)buildFrames 
{    
    //... 
        // 3. Create the UITextView
//        UITextView *textView = [[UITextView alloc] initWithFrame:textViewRect
//                                                   textContainer:textContainer];
//        [self addSubview:textView];
	//...
}


//Add the following to the very end of the buildFrames method:

- (void)buildFrames 
{    
    //... 
    [self buildViewsForCurrentOffset];
}


//add a few utility methods

#pragma mark - utility methods

//returns all the instances of UITextView that have been added as subviews of BookView

- (NSArray *)textSubViews
{
    NSMutableArray *views = [NSMutableArray new];
    
    for (UIView *subview in self.subviews) {
        if ([subview class] == [UITextView class]) {
            [views addObject:subview];
        }
    }
    return views;
}


//returns the owning UITextView for the NSTextContainer instance passed in, if one exists

- (UITextView *)textViewForContainer:(NSTextContainer *)textContainer
{
    for (UITextView *textView in [self textSubViews]) {
        
        if (textView.textContainer == textContainer) {
            
        return textView;
        }
    }
    return nil;
}


//preloads the left and right scroll views before the user actually scrolls the view

- (BOOL)shouldRenderView:(CGRect)viewFrame
{
    if (viewFrame.origin.x + viewFrame.size.width < (self.contentOffset.x - self.bounds.size.width))
        return NO;
    
    if (viewFrame.origin.x > (self.contentOffset.x + self.bounds.size.width * 2.0))
        return NO;
    
    return YES;
}


//build the appropriate views for the current scroll offset
//creates the first four text views. two for the visible page, and two for the page to the right

- (void)buildViewsForCurrentOffset
{
    // 1. Iterate over all instances of NSTextContainer that have been added to the layout manager
    for(NSUInteger index = 0; index < _layoutManager.textContainers.count; index++) {
        
        // 2. Obtain the view that renders this container. textViewForContainer: will return nil if a view is not present
        NSTextContainer *textContainer = _layoutManager.textContainers[index];
        UITextView *textView = [self textViewForContainer:textContainer];
        
        // 3. Determine the frame for this view
        CGRect textViewRect = [self frameForViewAtIndex:index];
        
        if ([self shouldRenderView:textViewRect]) {
            
            // 4.  If it should be rendered, check whether it already exists. if not, create it.
            if (!textView) {
                NSLog(@"Adding view at index %u", index);
                UITextView* textView = [[UITextView alloc] initWithFrame:textViewRect textContainer:textContainer];
                [self addSubview:textView];
            }
            
        } else {
            
            // 5. If it shouldn’t be rendered, check if it exists already. If it does, remove it.
            if (textView) {
                NSLog(@"Deleting view at index %u", index);
                [textView removeFromSuperview];
            }
        }
    }
}


//invoke buildViewsForCurrentOffset method when the user scrolls

//BookView.h
//adopt the scroll view protocol by adding <UIScrollViewDelegate>

@interface BookView : UIScrollView <UIScrollViewDelegate>
                                                                                                                                                                               
//initWithFrame method, set the delegate property to reference self

- (id)initWithFrame:(CGRect)frame
{
    //...
    self.delegate = self; //for invoking buildViewsForCurrentOffset method when the user scrolls
}


//implement the delegate method that’s invoked when scrolling finishes

#pragma mark - UIScrollView 델리게이트 메소드

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    [self buildViewsForCurrentOffset];
}



//6. Adding a table of contents

//Add a new class. Name the class Chapter, make it a subclass of NSObject

//Chapter.h

@interface Chapter : NSObject

@property (nonatomic, copy) NSString *title;
@property (nonatomic, assign) NSUInteger location;

@end                                                                                                                                                                                                                             

//AppDelegate.h

#import <UIKit/UIKit.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate>
//...
@property (nonatomic, strong) NSArray *chapters; //exposes an array of chapters

@end


//AppDelegate.m

#import "Chapter.h"

//looks for the “CHAPTER” keyword 
//and builds up an array of Chapter instances to mark their respective locations in the book based on the offset in the text.

- (NSMutableArray *)locateChapters:(NSString *)markdown
{
    NSMutableArray *chapters = [NSMutableArray new];
    [markdown enumerateSubstringsInRange:NSMakeRange(0, markdown.length)
                                 options:NSStringEnumerationByLines usingBlock:^(NSString *substring,
                                                                                 NSRange substringRange,
                                                                                 NSRange enclosingRange,
                                                                                 BOOL *stop) {
                                     if (substring.length > 7 && [[substring substringToIndex:7] isEqualToString:@"CHAPTER"]) {
                                        
                                         Chapter *chapter = [Chapter new];
                                         chapter.title = substring;
                                         chapter.location = substringRange.location;
                                         [chapters addObject:chapter];
                                     }
                                 }];
    return chapters;
}


//add the following line to application:didFinishLaunchingWithOptions:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{   
    //...
    
    self.chapters = [self locateChapters:self.bookMarkup.string];
        
    return YES;
}


//ChaptersViewController.m

#import "AppDelegate.h" 
#import "Chapter.h"


#pragma mark - obtains the chapter array from the app delegate

//convenience method that obtains the chapter array from the app delegate

- (NSArray *)chapters
{
    AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
    
    return appDelegate.chapters;
}


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [self chapters].count;;
}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    //...
    Chapter *chapter = [self chapters][indexPath.row];
    cell.textLabel.text = chapter.title;

    return cell;
}



//7. Adding chapter navigation

//ChaptersViewController.m

//ChaptersViewController.m

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    Chapter *chapter = [self chapters][indexPath.row];
    [self.bookViewController navigateToCharacterLocation:chapter.location];
}


//BookViewController.h

#import <UIKit/UIKit.h>

@interface BookViewController : UIViewController <UISplitViewControllerDelegate>

- (void)navigateToCharacterLocation:(NSUInteger)location;

@end


//BookViewController.m 

- (void)navigateToCharacterLocation:(NSUInteger)location
{
    [self.masterPopoverController dismissPopoverAnimated:YES];
    [_bookView navigateToCharacterLocation:location]; //relinquishes the responsibility of navigating to the required location to the BookView instance
}


//BookView.h

#import <UIKit/UIKit.h>

@interface BookView : UIScrollView <UIScrollViewDelegate>

//...
- (void)navigateToCharacterLocation:(NSUInteger)location;

@end


//BookView.m

//iterates over each of the NSTextContainer instances associated with the layout manager and obtains the instance’s glyph range. 
//then performs the critical step of converting the glyph range into a character range.
//For each instance of NSTextContainer, checks whether the required location is within the bounds of its characters range. 
//If so, it applies the scroll view offset and invokes buildViewForCurrentOffset to build the required views.

- (void)navigateToCharacterLocation:(NSUInteger)location {
    
    CGFloat offset = 0.0f;
    for (NSTextContainer *container in _layoutManager.textContainers) {
        
        NSRange glyphRange = [_layoutManager glyphRangeForTextContainer:container];
        NSRange charRange = [_layoutManager characterRangeForGlyphRange:glyphRange actualGlyphRange:nil];
       
        if (location >= charRange.location && location < NSMaxRange(charRange)) {
            
            //applies the scroll view offset and invokes buildViewForCurrentOffset to build the required views
            self.contentOffset = CGPointMake(offset, 0);
            [self buildViewsForCurrentOffset];
            return;
        }
        
        offset += self.bounds.size.width / 2.0f; }
}


//ChaptersViewController.m

- (void)awakeFromNib
{
    self.clearsSelectionOnViewWillAppear = YES;
    //When YES, the table view controller clears the table’s current selection when it receives a viewWillAppear: message. Setting this property to NO preserves the selection.
    //...
}



//8. Adding images

//replacing each Markdown image tag with an instance of NSTextAttachment that contains the requisite image.
//ex) ![Alt text](/path/to/image.png)

//Open MarkdownParser.m and add the following code to the parseMarkdownFile method

//MarkdownParser.m

- (NSAttributedString*)parseMarkdownFile:(NSString *)path {
    NSMutableAttributedString* parsedOutput = [[NSMutableAttributedString alloc] init];
    
    //...
    
    // locate images
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"\\!\\[.*\\]\\((.*)\\)"
                                                                           options:0
                                                                             error:nil];

    //cast out the escaping backslashes, and consider just the core regular expression, it looks like
    //\!\[.*\]\((.*)\)
    //1. \! - match an exclamation mark
    //2. \[.*\] - followed by some characters surrounded by square brackets, i.e. the alt-text
    //3. \((.*)\) - followed by some characters surrounded by round brackets, i.e. the image location.

    NSArray* matches = [regex matchesInString:[parsedOutput string]
                                      options:0
                                        range:NSMakeRange(0, parsedOutput.length)];
    
    // iterate over matches in reverse
    for (NSTextCheckingResult* result in [matches reverseObjectEnumerator]) {
        NSRange matchRange = [result range];
        NSRange captureRange = [result rangeAtIndex:1];
        
        // create an NSTextAttachment instance for each image
        NSTextAttachment* ta = [NSTextAttachment new];
        ta.image = [UIImage imageNamed:[parsedOutput.string substringWithRange:captureRange]];
        
        // image markdown is replaced with an attributed string based on the attachment
        NSAttributedString* rep = [NSAttributedString attributedStringWithAttachment:ta];
        [parsedOutput replaceCharactersInRange:matchRange withAttributedString:rep];
        
    }
    
    return parsedOutput;
}



//9. Adding dictionary lookups

//two steps: 1) finding and highlighting tapped words, 2) displaying the dictionary results.

//1) Finding and highlighting tapped words

//BookView.m

//add the following just below the self.delegate = self; statement in initWithFrame:

- (id)initWithFrame:(CGRect)frame
{
    //...
        // add a tap recognizer
        UITapGestureRecognizer* recognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTap:)];
        [self addGestureRecognizer:recognizer];
    //...
}


@implementation BookView
{
    //...
    NSRange _wordCharacterRange; // NSUInteger location, NSUInteger length. stores the character range of the word that was tapped
}


-(void)handleTap:(UITapGestureRecognizer*)tapRecognizer {
    
    NSTextStorage *textStorage = _layoutManager.textStorage;
    
    // 1. locate the tapped instance of UITextView
    CGPoint tappedLocation = [tapRecognizer locationInView:self];
    UITextView *tappedTextView = nil;
    
    for (UITextView *textView in [self textSubViews]) {
        
        if (CGRectContainsPoint(textView.frame, tappedLocation)) {
            tappedTextView = textView;
            break; }
    }
    
    if (!tappedTextView)
        return;
    
    // 2. convert the tap point into the coordinate system of the respective view
    // and subtract the text container’s margin
    CGPoint subViewLocation = [tapRecognizer locationInView:tappedTextView];
    subViewLocation.y -= 8.0;
    
    // 3. Determine the index of the tapped glyph using NSLayoutManager
    // and convert the glyph index into a character index.
    // This allows you to look up the corresponding character(s) in the text storage.
    NSUInteger glyphIndex = [_layoutManager glyphIndexForPoint:subViewLocation
                                               inTextContainer:tappedTextView.textContainer];
    NSUInteger charIndex = [_layoutManager characterIndexForGlyphAtIndex:glyphIndex];
    
    // 4. Determine whether the tapped character is a letter
    if (![[NSCharacterSet letterCharacterSet] characterIsMember:[textStorage.string
                                                                 characterAtIndex:charIndex]])
        return;
    
    // 5. Expand the character index into a word range
    _wordCharacterRange = [self wordThatContainsCharacter:charIndex
                                                   string:textStorage.string];
    
    // 6. apply a text color attribute to the word range
    [textStorage addAttribute:NSForegroundColorAttributeName
                        value:[UIColor redColor]
                        range:_wordCharacterRange];
}



//calculates the word range by searching backward and forward from the selected index
//until it finds the non-letter characters on either side of the word

- (NSRange) wordThatContainsCharacter:(NSUInteger)charIndex string:(NSString*)string {
    
    NSUInteger startLocation = charIndex;
    
    while(startLocation>0 && [[NSCharacterSet letterCharacterSet]
                              characterIsMember:[string characterAtIndex:startLocation-1]]) {
        startLocation--;
    }
    
    NSUInteger endLocation = charIndex;
    
    while(endLocation < string.length && [[NSCharacterSet letterCharacterSet]
                                          characterIsMember:[string characterAtIndex:endLocation+1]]) {
        endLocation++;
    }
    
    return NSMakeRange(startLocation, endLocation-startLocation+1);
}



//2) Displaying dictionary results

//Create a new protocol
//Objective-C protocol template -> Name the protocol BookViewDelegate

//BookViewDelegate.h

#import <Foundation/Foundation.h>

@class BookView;

@protocol BookViewDelegate <NSObject>

//informs delegates of BookView that a word has been tapped
- (void)bookView:(BookView *)bookView didHighlightWord:(NSString *)word inRect:(CGRect)rect;

@end


//BookView.h

//import BookViewDelegate.h and add a property

#import "BookViewDelegate.h"

@interface BookView : UIScrollView <UIScrollViewDelegate>

//...

@property (nonatomic, weak) id<BookViewDelegate> bookViewDelegate;

@end


//BookView.m
//locate the handleTap: method and add the following to the bottom of the implementation

-(void)handleTap:(UITapGestureRecognizer*)tapRecognizer {
    
    //...

    // 1. Obtains the relevant line fragment for the tapped glyph.
    CGRect rect = [_layoutManager lineFragmentRectForGlyphAtIndex:glyphIndex
                                                   effectiveRange:nil];
    
    // 2. Obtains the location of the first and last glyphs of the tapped word
    NSRange wordGlyphRange = [_layoutManager glyphRangeForCharacterRange:_wordCharacterRange
                                                    actualCharacterRange:nil];
    CGPoint startLocation = [_layoutManager locationForGlyphAtIndex:wordGlyphRange.location];
    CGPoint endLocation = [_layoutManager locationForGlyphAtIndex:NSMaxRange(wordGlyphRange)];
    
    // 3. Calculates the rectangle of the selected word
    //by using the height of the line fragment and the position of the start and end glyphs in the word
    CGRect wordRect = CGRectMake(startLocation.x, rect.origin.y, endLocation.x - startLocation.x, rect.size.height);
    
    // 4. Converts the resulting rectangle into the coordinate system
    wordRect = CGRectOffset(wordRect, tappedTextView.frame.origin.x, tappedTextView.frame.origin.y); // CGRect rect, CGFloat dx, CGFloat dy
    
    // 5. Adjusts the rectangle by the margin offset, and invokes the newly added delegate method.
    wordRect = CGRectOffset(wordRect, 0.0, 8.0);
    NSString* word = [textStorage.string substringWithRange:_wordCharacterRange];
    
    [self.bookViewDelegate bookView:self didHighlightWord:word inRect:wordRect];
}


//BookViewController.m

#import "BookViewDelegate.h"

//adopt BookView delegate, together with the popover delegate:

@interface BookViewController () <BookViewDelegate, UIPopoverControllerDelegate>

//viewDidLoad method, set the view controller as the book view’s delegate:

- (void)viewDidLoad
{
    //...
    _bookView.bookViewDelegate = self; //set the view controller as the book view’s delegate
}


//add instance variable for the popover

@implementation BookViewController
{
    //...
    UIPopoverController* _popover; //instance variable for the popover
}


//book view delegate method which is invoked when a word is tapped.

#pragma mark - BookViewDelegate method

- (void)bookView:(BookView *)bookView didHighlightWord:(NSString *)word inRect:(CGRect)rect
{
    UIReferenceLibraryViewController *dictionaryVC = [[UIReferenceLibraryViewController alloc]
                                                      initWithTerm: word];
    
    _popover.contentViewController = dictionaryVC;
    _popover = [[UIPopoverController alloc] initWithContentViewController:dictionaryVC];
    _popover.delegate = self;
    
    //‘presented’ at the location of the tapped word
    [_popover presentPopoverFromRect:rect
                              inView:_bookView
            permittedArrowDirections:UIPopoverArrowDirectionAny
                            animated:YES];
}



- (void)popoverControllerDidDismissPopover: (UIPopoverController *)popoverController
{
    [_bookView removeWordHighlight]; //informs the BookView instance that the word highlight should be removed.
}



//BookView.h

//add the following method to the interface declaration

- (void)removeWordHighlight; //when the popover is closed, word highlight should be removed.


//BookView.m

- (void)removeWordHighlight
{
    //when the popover is closed, word highlight should be removed.
    [_layoutManager.textStorage removeAttribute:NSForegroundColorAttributeName
                                          range:_wordCharacterRange];
}