Add custom shortcut item to 3D Touch menus on iOS 13+

MenuItems.m

// MenuItems.m
// (*.m) for gist formatting

// Makefile

TWEAK_NAME = YourTweak
YourTweak_PRIVATE_FRAMEWORKS = SpringBoardServices

// Tweak.h

@interface SBSApplicationShortcutIcon: NSObject
@end

@interface SBSApplicationShortcutItem : NSObject
@property (nonatomic, retain) NSString *type;
@property (nonatomic, copy) NSString * localizedTitle;
@property (nonatomic, copy) SBSApplicationShortcutIcon * icon;
@property (nonatomic, copy) NSString * bundleIdentifierToLaunch;
- (void)setIcon:(SBSApplicationShortcutIcon *)arg1;
@end

@interface SBSApplicationShortcutCustomImageIcon : SBSApplicationShortcutIcon
@property (nonatomic, readwrite) BOOL isTemplate;   
- (id)initWithImagePNGData:(id)arg1;
- (BOOL)isTemplate;
@end

// Tweak.xm

%hook SBIconView
- (void)setApplicationShortcutItems:(NSArray *)arg1 {
	NSMutableArray *newItems = [[NSMutableArray alloc] init];
	for (SBSApplicationShortcutItem *item in arg1) {
		[newItems addObject:item];
	}
	NSData *lightData = UIImagePNGRepresentation([[UIImage imageWithContentsOfFile:@"/Library/Application Support/Tweak.bundle/light.png"] imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate]);
	NSData *darkData = UIImagePNGRepresentation([[UIImage imageWithContentsOfFile:@"/Library/Application Support/Tweak.bundle/dark.png"] imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate]);
	
	SBSApplicationShortcutItem *newItem = [%c(SBSApplicationShortcutItem) alloc];
	newItem.localizedTitle = @"New Title";
	newItem.localizedSubtitle = @"New Subtitle";
	newItem.type = @"com.yout.tweak.itemIdentifier";
	SBSApplicationShortcutCustomImageIcon *lightIcon = [[SBSApplicationShortcutCustomImageIcon alloc] initWithImagePNGData:lightData];
	SBSApplicationShortcutCustomImageIcon *darkIcon = [[SBSApplicationShortcutCustomImageIcon alloc] initWithImagePNGData:darkData];
	
	if (/* Check for dark mode */ == YES) {
		[newItem setIcon:darkIcon];
	} else {
		[newItem setIcon:lightIcon];
	}
	[newItems addObject:newItem];
	%orig(newItems);
}
+ (void)activateShortcut:(SBSApplicationShortcutItem *)item withBundleIdentifier:(NSString *)bundleID forIconView:(SBIconView *)iconView {
	if ([[item type] isEqualToString:@"com.your.tweak.itemIdentifier"]) {
		// Do select action here
	} else {
		%orig;
	}
}
%end