iOS Keyboard Handling with a Base View Controller

BaseViewController.h

#import <UIKit/UIKit.h>

@interface BaseViewController : UIViewController

#pragma mark - Keyboard Methods
#pragma mark -

- (void)hideKeyboardWithoutAnimation;
- (void)keyboardWillShowWithHeight:(CGFloat)height duration:(CGFloat)duration animationOptions:(UIViewAnimationOptions)animationOptions;
- (void)keyboardWillHideWithHeight:(CGFloat)height duration:(CGFloat)duration animationOptions:(UIViewAnimationOptions)animationOptions;
- (void)keyboardDidShow;
- (void)keyboardDidHide;

@end

BaseViewController.m

#import "BaseViewController.h"

@interface BaseViewController ()

@end

@implementation BaseViewController {
    BOOL isKeyboardVisible;
}

#pragma mark - View Lifecycle
#pragma mark -

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardWillShowNotification:)
                                                 name:UIKeyboardWillShowNotification
                                               object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardWillHideNotification:)
                                                 name:UIKeyboardWillHideNotification
                                               object:nil];
    
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardDidShowNotification:)
                                                 name:UIKeyboardDidShowNotification
                                               object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardDidHideNotification:)
                                                 name:UIKeyboardDidHideNotification
                                               object:nil];
    
    self.navigationController.navigationBar.backgroundColor = self.view.backgroundColor;
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    
    [[NSNotificationCenter defaultCenter] removeObserver:self
                                                    name:UIKeyboardWillShowNotification
                                                  object:nil];
    [[NSNotificationCenter defaultCenter] removeObserver:self
                                                    name:UIKeyboardWillHideNotification
                                                  object:nil];
    
    [[NSNotificationCenter defaultCenter] removeObserver:self
                                                    name:UIKeyboardDidShowNotification
                                                  object:nil];
    [[NSNotificationCenter defaultCenter] removeObserver:self
                                                    name:UIKeyboardDidHideNotification
                                                  object:nil];
}

#pragma mark - Keyboard Methods
#pragma mark -

- (void)hideKeyboardWithoutAnimation {
    [self keyboardWillHideWithHeight:0.0 duration:0.0 animationOptions:kNilOptions];
}

- (void)keyboardWillShowWithHeight:(CGFloat)height duration:(CGFloat)duration animationOptions:(UIViewAnimationOptions)animationOptions {
    // override if necessary
    
    DebugLog(@"%@", NSStringFromSelector(_cmd));
    
    UIScrollView *scrollView = [self mainScrollView];
    if (scrollView) {
        CGFloat bottom = self.bottomLayoutGuide.length;
        
        UIEdgeInsets contentInset = scrollView.contentInset;
        contentInset.bottom = bottom + height;
        
        UIEdgeInsets scrollIndicatorInsets = scrollView.scrollIndicatorInsets;
        scrollIndicatorInsets.bottom = contentInset.bottom;
        
        [UIView animateWithDuration:duration delay:0.0 options:animationOptions animations:^{
            scrollView.contentInset = contentInset;
            scrollView.scrollIndicatorInsets = scrollIndicatorInsets;
        } completion:^(BOOL finished) {
        }];
    }
}

- (void)keyboardWillHideWithHeight:(CGFloat)height duration:(CGFloat)duration animationOptions:(UIViewAnimationOptions)animationOptions {
    // override if necessary
    
    DebugLog(@"%@", NSStringFromSelector(_cmd));
    
    UIScrollView *scrollView = [self mainScrollView];
    if (scrollView) {
        CGFloat bottom = self.bottomLayoutGuide.length;
        
        UIEdgeInsets contentInset = scrollView.contentInset;
        contentInset.bottom = bottom;
        
        UIEdgeInsets scrollIndicatorInsets = scrollView.scrollIndicatorInsets;
        scrollIndicatorInsets.bottom = contentInset.bottom;
        
        [UIView animateWithDuration:duration delay:0.0 options:animationOptions animations:^{
            scrollView.contentInset = contentInset;
            scrollView.scrollIndicatorInsets = scrollIndicatorInsets;
        } completion:^(BOOL finished) {
        }];
    }
}

- (void)keyboardDidShow {
    // override if necessary
}

- (void)keyboardDidHide {
    // override if necessary
}

#pragma mark - Notifications
#pragma mark -

- (void)keyboardWillShowNotification:(NSNotification *)notification {
	CGFloat height = [self getKeyboardHeight:notification forBeginning:TRUE];
	NSTimeInterval duration = [self getDuration:notification];
    UIViewAnimationCurve animationCurve = [self getAnimationCurve:notification];
    UIViewAnimationOptions animationOptions = [self animationOptionsWithCurve:animationCurve];
    
    [self keyboardWillShowWithHeight:height duration:duration animationOptions:animationOptions];
}

- (void)keyboardWillHideNotification:(NSNotification *)notification {
	CGFloat height = [self getKeyboardHeight:notification forBeginning:FALSE];
	NSTimeInterval duration = [self getDuration:notification];
    UIViewAnimationCurve animationCurve = [self getAnimationCurve:notification];
    UIViewAnimationOptions animationOptions = [self animationOptionsWithCurve:animationCurve];
    
    [self keyboardWillHideWithHeight:height duration:duration animationOptions:animationOptions];
}

- (void)keyboardDidShowNotification:(NSNotification *)notification {
    isKeyboardVisible = TRUE;
    [self keyboardDidShow];
}

- (void)keyboardDidHideNotification:(NSNotification *)notification {
    isKeyboardVisible = FALSE;
    [self keyboardDidHide];
}

#pragma mark - Private
#pragma mark -

- (NSTimeInterval)getDuration:(NSNotification *)notification {
	NSTimeInterval duration;
	NSValue *durationValue = [notification.userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey];
	[durationValue getValue:&duration];
	
	return duration;
}

- (CGFloat)getKeyboardHeight:(NSNotification *)notification forBeginning:(BOOL)forBeginning {
	NSDictionary *info = [notification userInfo];
	
	CGFloat keyboardHeight;
    
    NSValue *boundsValue = nil;
    if (forBeginning) {
        boundsValue = [info valueForKey:UIKeyboardFrameBeginUserInfoKey];
    }
    else {
        boundsValue = [info valueForKey:UIKeyboardFrameEndUserInfoKey];
    }
    
    UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation];
    if (UIDeviceOrientationIsLandscape(orientation)) {
        keyboardHeight = [boundsValue CGRectValue].size.width;
    }
    else {
        keyboardHeight = [boundsValue CGRectValue].size.height;
    }
    
	return keyboardHeight;
}

- (UIViewAnimationCurve)getAnimationCurve:(NSNotification *)notification {
    UIViewAnimationCurve animationCurve;
	NSValue *animationCurveValue = [notification.userInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey];
    [animationCurveValue getValue:&animationCurve];
    
    return animationCurve;
}

- (UIViewAnimationOptions)animationOptionsWithCurve:(UIViewAnimationCurve)curve {
    switch (curve) {
        case UIViewAnimationCurveEaseInOut:
            return UIViewAnimationOptionCurveEaseInOut;
        case UIViewAnimationCurveEaseIn:
            return UIViewAnimationOptionCurveEaseIn;
        case UIViewAnimationCurveEaseOut:
            return UIViewAnimationOptionCurveEaseOut;
        case UIViewAnimationCurveLinear:
            return UIViewAnimationOptionCurveLinear;
        default:
            // return whatever it provided because iOS 7 uses an undocumented animation value of 7 (not cool, Apple)
            // http://stackoverflow.com/questions/18837166/how-to-mimic-keyboard-animation-on-ios-7-to-add-done-button-to-numeric-keyboar
            return (UIViewAnimationOptions)UIViewAnimationOptionCurveLinear;
    }
}

- (UIScrollView *)mainScrollView {
    UIScrollView *scrollView = nil;
    if (self.view.subviews.count && [self.view.subviews[0] isKindOfClass:[UIScrollView class]]) {
        scrollView = (UIScrollView *)self.view.subviews[0];
    }
    return scrollView;
}

- (UIView *)mainContentView {
    UIView *contentView = nil;
    UIScrollView *scrollView = [self mainScrollView];
    if (scrollView && scrollView.subviews.count) {
        contentView = scrollView.subviews[0];
    }
    
    return contentView;
}

@end