Simplified iOS menu view wired up to UIMenuBuilder

MRDMenuView.h

//
//  MRDMenuView.h
//  MobileRadio
//
//  Created by Steven Troughton-Smith on 29/02/2020.
//  Copyright © 2020 High Caffeine Content. All rights reserved.
//

#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

@class MRDMenuContentsView;
@interface MRDMenuView : UIView <UIMenuBuilder>
{
	MRDMenuContentsView *contentsView;
	
	UILabel *rootMenuTitleLabel;
	UIImageView *rootMenuImageView;
}

@property NSMutableDictionary *menu;

@property BOOL open;

@end

NS_ASSUME_NONNULL_END

MRDMenuView.m

//
//  MRDMenuView.m
//  MobileRadio
//
//  Created by Steven Troughton-Smith on 29/02/2020.
//  Copyright © 2020 High Caffeine Content. All rights reserved.
//

#import "MRDMenuView.h"
#import "AppDelegate.h"

#define MRDMenuCornerRadius 8.0

@interface MRDMenuItemView : UIView
{
	UILabel *titleLabel;
	UILabel *shortcutLabel;
}

@property NSString *title;
@property NSString *shortcut;
@property BOOL separator;
@property BOOL enabled;

@property (strong) UIMenuElement *menu;

@end

@implementation MRDMenuItemView

- (instancetype)initWithFrame:(CGRect)frame
{
	self = [super initWithFrame:frame];
	if (self) {
		titleLabel = [UILabel new];
		
		shortcutLabel = [UILabel new];
		shortcutLabel.textAlignment = NSTextAlignmentRight;
		
		[self addSubview:titleLabel];
		[self addSubview:shortcutLabel];
		
		self.enabled = YES;
		
	}
	return self;
}

- (void)layoutSubviews
{
	CGFloat padding = 20;
	CGFloat shortcutWidth = 60;
	CGFloat maxWidth = self.bounds.size.width -(padding *2) - shortcutWidth;
	
	titleLabel.frame = CGRectMake(padding, 0, maxWidth, self.bounds.size.height);
	shortcutLabel.frame = CGRectMake(self.bounds.size.width-shortcutWidth-padding, 0, shortcutWidth, self.bounds.size.height);
	
	titleLabel.text = self.title;
	shortcutLabel.text = self.shortcut;
	
	if (self.separator)
	{
		self.backgroundColor = [UIColor secondarySystemFillColor];
	}
	else
	{
		self.backgroundColor = nil;
	}
	
	titleLabel.enabled = self.enabled;
	shortcutLabel.enabled = self.enabled;
}

-(void)startSelectionAnimation
{
	if (self.separator)
		return;;
	
	[self performCommand];
	[self unhighlight];
	
	CGFloat blinkDelay = 0.08;
	
	dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(blinkDelay * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
		[self highlight];
		dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(blinkDelay * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
			[self unhighlight];
			dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(blinkDelay * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
				
				[[NSNotificationCenter defaultCenter] postNotificationName:@"MRDMenuItemSelected" object:self];
			});
			
		});
	});
}

-(void)performCommand
{
	if (!self.enabled)
		return;
	
	if ([self.menu isKindOfClass:NSClassFromString(@"UIKeyCommand")])
	{
		UIKeyCommand *command = (UIKeyCommand *)self.menu;
		
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
		[[[UIApplication sharedApplication] delegate] performSelector:[command action] withObject:self];
#pragma clang diagnostic pop
	}
}

-(void)highlight
{
	if (self.separator || !self.enabled)
		return;
	
	self.backgroundColor = [UIColor systemBlueColor];
	titleLabel.textColor = [UIColor whiteColor];
	shortcutLabel.textColor = [UIColor whiteColor];
}

-(void)unhighlight
{
	if (self.separator || !self.enabled)
		return;;
	
	self.backgroundColor = nil;
	titleLabel.textColor = [UIColor labelColor];
	shortcutLabel.textColor = [UIColor labelColor];
}

@end

@interface MRDMenuContentsView : UIView
{
	UIVisualEffectView *effectView;
	UIView *shadowView;
	UIView *headerView;
}

@property NSArray <MRDMenuItemView *>*menuItemViews;

-(void)selectPosition:(CGPoint)p;
-(void)setHighlightedPosition:(CGPoint)p;

@end

@implementation MRDMenuContentsView

- (instancetype)initWithFrame:(CGRect)frame
{
	self = [super initWithFrame:frame];
	if (self)
	{
		effectView = [[UIVisualEffectView alloc] initWithEffect:[UIBlurEffect effectWithStyle:UIBlurEffectStyleProminent]];
		shadowView = [UIView new];
		
		headerView = [UIView new];
		headerView.backgroundColor = [UIColor systemBlueColor];
		
		[self addSubview:shadowView];
		[self addSubview:effectView];
		[[effectView contentView] addSubview:headerView];
		
		shadowView.layer.shadowOpacity = 0.4;
		shadowView.layer.shadowRadius = 7;
		shadowView.layer.shadowColor = [UIColor colorWithRed:103/255 green:165/255 blue:162/255 alpha:1.].CGColor;
	}
	return self;
}

-(UIBezierPath *)computePathWithParentView:(UIView *)parent
{
	/* Ported from https://github.com/TwoLivesLeft/Menu */
	
	CGRect localViewBounds;
	UIRectCorner lowerRectCorners;
	
	localViewBounds = parent.bounds;
	lowerRectCorners = (UIRectCornerTopRight | UIRectCornerBottomLeft | UIRectCornerBottomRight);
	
	UIBezierPath *topPath = [UIBezierPath bezierPathWithRoundedRect:localViewBounds byRoundingCorners:(UIRectCornerTopLeft | UIRectCornerTopRight) cornerRadii:CGSizeMake(MRDMenuCornerRadius, MRDMenuCornerRadius)];
	
	UIBezierPath *midPath = [UIBezierPath new];
	
	[midPath moveToPoint:CGPointMake(localViewBounds.origin.x, localViewBounds.origin.y + localViewBounds.size.height)];
	[midPath addLineToPoint:CGPointMake(localViewBounds.origin.x, localViewBounds.origin.y + localViewBounds.size.height + MRDMenuCornerRadius)];
	[midPath addLineToPoint:CGPointMake(localViewBounds.origin.x+localViewBounds.size.width+MRDMenuCornerRadius, localViewBounds.origin.y + localViewBounds.size.height + MRDMenuCornerRadius)];
	
	[midPath addArcWithCenter:CGPointMake(localViewBounds.origin.x + localViewBounds.size.width+MRDMenuCornerRadius, localViewBounds.origin.y + localViewBounds.size.height) radius:MRDMenuCornerRadius startAngle:M_PI_2 endAngle:M_PI clockwise:YES];
	[midPath addLineToPoint:CGPointMake(localViewBounds.origin.x, localViewBounds.origin.y + localViewBounds.size.height)];
	
	[midPath closePath];
	
	CGFloat yOffset = localViewBounds.origin.y + localViewBounds.size.height + MRDMenuCornerRadius;
	
	UIBezierPath *bottomPath = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, yOffset, self.bounds.size.width, self.bounds.size.height - yOffset) byRoundingCorners:lowerRectCorners cornerRadii:CGSizeMake(MRDMenuCornerRadius, MRDMenuCornerRadius)];
	
	[topPath appendPath:midPath];
	[topPath appendPath:bottomPath];
	
	return topPath;
}

-(void)generateMaskAndShadow
{
	UIBezierPath *path = [self computePathWithParentView:self.superview];
	
	CAShapeLayer *shapeLayer = [CAShapeLayer layer];
	shapeLayer.path = path.CGPath;
	effectView.layer.mask = shapeLayer;
	
	
	[path applyTransform:CGAffineTransformMakeTranslation(20, 20)];
	
	CALayer *shadowLayer = shadowView.layer;
	
	shadowLayer.shadowPath = path.CGPath;
	shadowLayer.shadowOffset = CGSizeMake(0, 6);
	
	UIGraphicsImageRenderer *imageRenderer = [[UIGraphicsImageRenderer alloc] initWithSize:shadowView.bounds.size];
	
	UIImage *shadowMask = [imageRenderer imageWithActions:^(UIGraphicsImageRendererContext * _Nonnull rendererContext) {
		[[UIColor whiteColor] setFill];
		[rendererContext fillRect:shadowView.bounds];
		[path fillWithBlendMode:kCGBlendModeClear alpha:1.0];
	}];
	
	CALayer *imageMask = [CALayer layer];
	imageMask.frame = shadowView.bounds;
	imageMask.contents = (__bridge id _Nullable)(shadowMask.CGImage);
	
	shadowLayer.mask = imageMask;
}

-(void)relayoutContents
{
	CGFloat y = self.superview.frame.size.height + MRDMenuCornerRadius*3; // inner and outer at the L join, plus bottom radius
	
	CGFloat longestItemTitle = 0;
	
	for (MRDMenuItemView *item in self.menuItemViews)
	{
		CGSize sz = [item.title sizeWithAttributes:@{NSFontAttributeName: [UIFont systemFontOfSize:17]}];
		
		sz.width += 20+60+20;
		
		if (sz.width > longestItemTitle)
		{
			longestItemTitle = sz.width;
		}
	}
	
	for (MRDMenuItemView *item in self.menuItemViews)
	{
		CGFloat menuHeight = 40;
		
		if (item.separator)
			menuHeight = 2;
		
		item.frame = CGRectMake(0, y, longestItemTitle, menuHeight);
		
		[[effectView contentView] addSubview:item];
		
		y+= menuHeight;
	}
	
	y += MRDMenuCornerRadius;
	
	self.frame = CGRectMake(self.frame.origin.x, self.frame.origin.y, longestItemTitle, y);
	effectView.frame = self.bounds;
	shadowView.frame = CGRectInset(self.bounds, -20, -20);
	
	headerView.frame = self.superview.bounds;
	CGRect hf = headerView.frame;
	hf.size.height += MRDMenuCornerRadius*2;
	hf.size.width = self.frame.size.width;
	headerView.frame = hf;
}

-(void)selectPosition:(CGPoint)p
{
	for (MRDMenuItemView *view in self.menuItemViews)
	{
		CGPoint p1 = [self convertPoint:p toView:view];
		
		if ([view pointInside:p1 withEvent:nil])
		{
			[view startSelectionAnimation];
		}
	}
}

-(void)setHighlightedPosition:(CGPoint)p
{
	for (MRDMenuItemView *view in self.menuItemViews)
	{
		CGPoint p1 = [self convertPoint:p toView:view];
		
		if ([view pointInside:p1 withEvent:nil])
		{
			[view highlight];
		}
		else
		{
			[view unhighlight];
		}
	}
}

@end

@implementation MRDMenuView

- (instancetype)initWithFrame:(CGRect)frame
{
	self = [super initWithFrame:frame];
	if (self) {
		
		self.backgroundColor = nil;
		self.opaque = NO;
		
		rootMenuTitleLabel = [UILabel new]; /* Unused */
		rootMenuTitleLabel.text = NSLocalizedString(@"SOFTWARE_MENU_TITLE", nil);
		rootMenuTitleLabel.textAlignment = NSTextAlignmentCenter;
		
		rootMenuImageView = [UIImageView new];
		rootMenuImageView.contentMode = UIViewContentModeCenter;
		rootMenuImageView.tintColor = [[UIColor labelColor] colorWithAlphaComponent:0.7];
		
		UIImageSymbolConfiguration *config = [UIImageSymbolConfiguration configurationWithPointSize:24 weight:UIImageSymbolWeightSemibold];
		UIImage *icon = [UIImage systemImageNamed:@"command" withConfiguration:config];
		
		rootMenuImageView.image = icon;
		
		[self addSubview:rootMenuImageView];
		
		UILongPressGestureRecognizer *recognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPress:)];
		recognizer.minimumPressDuration = 0;
		
		[self addGestureRecognizer:recognizer];
		
		[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(hideContents) name:@"MRDMenuItemSelected" object:nil];
	}
	return self;
}

- (void)layoutSubviews
{
	[super layoutSubviews];
	
	rootMenuTitleLabel.frame = self.bounds;
	rootMenuImageView.frame = self.bounds;
}

- (void)drawRect:(CGRect)rect
{
	[[UIColor secondarySystemFillColor] setFill];
	[[UIBezierPath bezierPathWithRoundedRect:CGRectMake(20, self.bounds.size.height-3, self.bounds.size.width-40, 3) cornerRadius:2] fill];
}

#pragma mark - Menu Builder

-(id)system
{
	return self;
}

- (void)insertChildMenu:(nonnull UIMenu *)childMenu atEndOfMenuForIdentifier:(nonnull UIMenuIdentifier)parentIdentifier
{
	UIMenu *parentMenu = self.menu[parentIdentifier];
	parentMenu = [parentMenu menuByReplacingChildren:[parentMenu.children arrayByAddingObject:childMenu]];
	self.menu[parentIdentifier] = parentMenu;
}

- (void)insertChildMenu:(nonnull UIMenu *)childMenu atStartOfMenuForIdentifier:(nonnull UIMenuIdentifier)parentIdentifier
{
	UIMenu *parentMenu = self.menu[parentIdentifier];
	parentMenu = [parentMenu menuByReplacingChildren:[@[childMenu] arrayByAddingObjectsFromArray:parentMenu.children]];
	self.menu[parentIdentifier] = parentMenu;
}

- (nullable UIMenu *)menuForIdentifier:(nonnull UIMenuIdentifier)identifier
{
	return [self.menu objectForKey:identifier];
}

- (void)removeMenuForIdentifier:(nonnull UIMenuIdentifier)removedIdentifier
{
	[self.menu removeObjectForKey:removedIdentifier];
}

- (void)replaceMenuForIdentifier:(nonnull UIMenuIdentifier)replacedIdentifier withMenu:(nonnull UIMenu *)replacementMenu
{
	self.menu[replacedIdentifier] = replacementMenu;
}

#pragma mark - Unused

- (void)insertSiblingMenu:(nonnull UIMenu *)siblingMenu afterMenuForIdentifier:(nonnull UIMenuIdentifier)siblingIdentifier
{
}

- (void)insertSiblingMenu:(nonnull UIMenu *)siblingMenu beforeMenuForIdentifier:(nonnull UIMenuIdentifier)siblingIdentifier
{
}

- (void)replaceChildrenOfMenuForIdentifier:(nonnull UIMenuIdentifier)parentIdentifier fromChildrenBlock:(NSArray<UIMenuElement *> *(NS_NOESCAPE ^)(NSArray<UIMenuElement *> *))childrenBlock
{
	
}

- (nullable UIAction *)actionForIdentifier:(nonnull UIActionIdentifier)identifier
{
	return nil;
}

- (nullable UICommand *)commandForAction:(nonnull SEL)action propertyList:(nullable id)propertyList
{
	
	return nil;
}


#pragma mark - Menu

-(void)populateInitialMenu
{
	/* iOS, unlike macOS, doesn't start with any menu bar menus */
	
	self.menu = [NSMutableDictionary dictionary];
	self.menu[UIMenuFile] = [UIMenu menuWithTitle:NSLocalizedString(@"File", nil) children:@[]];
	self.menu[UIMenuEdit] = [UIMenu menuWithTitle:NSLocalizedString(@"Edit", nil) children:@[]];
	self.menu[UIMenuView] = [UIMenu menuWithTitle:NSLocalizedString(@"View", nil) children:@[]];
	self.menu[UIMenuHelp] = [UIMenu menuWithTitle:NSLocalizedString(@"Help", nil) children:@[]];
}

-(NSArray <MRDMenuItemView *>*)_buildMenuItemViewsForMenu:(UIMenu *)element
{
	NSMutableArray *array = [NSMutableArray array];
	
	for (UIMenuElement *child in element.children)
	{
		MRDMenuItemView *menuItemView = [MRDMenuItemView new];
		
		if ([child isKindOfClass:NSClassFromString(@"UIKeyCommand")])
		{
			UIKeyCommand *command = (UIKeyCommand *)child;
			
			NSMutableString *shortcut = [NSMutableString string];
			NSMutableString *title = [NSMutableString string];
			
			if (command.modifierFlags & UIKeyModifierControl)
				[shortcut appendString:@"⌃"];
			
			if (command.modifierFlags & UIKeyModifierAlternate)
				[shortcut appendString:@"⌥"];
			
			if (command.modifierFlags & UIKeyModifierShift)
				[shortcut appendString:@"⇧"];
			
			if (command.modifierFlags & UIKeyModifierCommand)
				[shortcut appendString:@"⌘"];
			
			[shortcut appendString:command.input];
			
			menuItemView.shortcut = [NSString stringWithFormat:@"%@", shortcut];
			
			/*
			 if (command.state == UIMenuElementStateOn)
			 [title appendString:@"􀆅 "];
			 else if (command.state == UIMenuElementStateMixed)
			 [title appendString:@"- "];
			 */
			
			if (command.attributes & UIMenuElementAttributesDisabled)
				menuItemView.enabled = NO;
			
			[title appendString:command.title];
			
			menuItemView.title = [NSString stringWithFormat:@"%@", title];
			menuItemView.menu = command;
		}
		
		if ([child isKindOfClass:NSClassFromString(@"UIMenu")])
		{
			[array addObjectsFromArray:[self _buildMenuItemViewsForMenu:(UIMenu *)child]];
			
			menuItemView.menu = child;
		}
		else
			[array addObject:menuItemView];
		
	}
	
	return [NSArray arrayWithArray:array];
}

#pragma mark - Input

- (void)showContents
{
	if (self.open)
		return;
	
	[self populateInitialMenu];
	
	[(AppDelegate *)([[UIApplication sharedApplication] delegate]) buildMenuWithBuilder:self];
	
	contentsView = [MRDMenuContentsView new];
	
	NSMutableArray *items = [NSMutableArray array];
	
	for (NSString *identifier in @[UIMenuFile, UIMenuView, UIMenuHelp])
	{
		UIMenu *menu = self.menu[identifier];
		
		[items addObjectsFromArray:[self _buildMenuItemViewsForMenu:menu]];
		
		if (![identifier isEqualToString:UIMenuHelp])
		{
			MRDMenuItemView *menuItemView = [MRDMenuItemView new];
			menuItemView.separator = YES;
			[items addObject:menuItemView];
		}
	}
	
	contentsView.menuItemViews = items;
	
	rootMenuImageView.tintColor = [UIColor whiteColor];
	
	[self insertSubview:contentsView belowSubview:rootMenuImageView];
	[contentsView relayoutContents];
	
	[contentsView generateMaskAndShadow];
	
	self.open = YES;
	
}

-(void)hideContents
{
	[UIView animateWithDuration:0.3 animations:^{
		self->contentsView.alpha = 0;
		self->rootMenuImageView.tintColor = [[UIColor labelColor] colorWithAlphaComponent:0.7];
	} completion:^(BOOL finished) {
		self->contentsView.frame = self.bounds;
		self.open = NO;
	}];
}

-(void)longPress:(UILongPressGestureRecognizer *)recognizer
{
	if (contentsView)
	{
		CGPoint p1 = [recognizer locationInView:self];
		CGPoint p2 = [self convertPoint:p1 toView:contentsView];
		
		[contentsView setHighlightedPosition:CGPointMake(p2.x, p1.y)];
	}
	
	switch (recognizer.state)
	{
		case UIGestureRecognizerStateBegan:
			[self showContents];
			break;
			
		case UIGestureRecognizerStateCancelled:
		case UIGestureRecognizerStateEnded:
		{
			CGPoint p2 = [self convertPoint:[recognizer locationInView:self] toView:contentsView];
			
			if ([contentsView pointInside:p2 withEvent:nil])
			{
				[contentsView selectPosition:p2];
			}
			
			CGRect menuContentsRect = contentsView.bounds;
			
			menuContentsRect.origin.y += self.bounds.size.height + MRDMenuCornerRadius*2;
			menuContentsRect.size.height -= (self.bounds.size.height + MRDMenuCornerRadius*4);
			
			CGPoint p3 = [recognizer locationInView:self];
			if (!CGRectContainsPoint(menuContentsRect, p3))
			{
				[self hideContents];
			}
		}
			
		default:
			break;
	}
	
}

- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
{
	if (contentsView)
	{
		CGPoint p = [self convertPoint:point toView:contentsView];
		
		return [contentsView pointInside:p withEvent:nil];
	}
	else
	{
		return [super pointInside:point withEvent:event];
	}
}

@end

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