myview.m

This is an example applications that shows how to handle multiple touches at the same time on the iP

/*

File: MyView.m
Abstract: MyView contains several subviews, each of which can be moved by touch.
Illustrates handling touch events, including multiple touches.

Version: 1.7

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*/


#import "MyView.h"
#import <QuartzCore/QuartzCore.h>  // Needed for animations


@interface MyView()
@property (nonatomic, retain) UIImageView *firstPieceView;
@property (nonatomic, retain) UIImageView *secondPieceView;
@property (nonatomic, retain) UIImageView *thirdPieceView;
@property (nonatomic, retain) UILabel *touchPhaseText;
@property (nonatomic, retain) UILabel *touchInfoText;
@property (nonatomic, retain) UILabel *touchTrackingText;
@property (nonatomic, retain) UILabel *touchInstructionsText;
@property (nonatomic) BOOL piecesOnTop;  
@property (nonatomic) CGPoint startTouchPosition;
@end


@interface MyView (PrivateMethods)
-(UILabel *) newLabelWithOffset:(float)offset numberOfLines:(NSUInteger) lines;
-(UIImageView *)newPieceViewWithImageNamed:(NSString *)imageName atPostion:(CGPoint)centerPoint;
-(void)animateFirstTouchAtPoint:(CGPoint)touchPoint forView:(UIImageView *)theView;
-(void)animateView:(UIImageView *)theView toPosition:(CGPoint) thePosition;
-(void) dispatchFirstTouchAtPoint:(CGPoint)touchPoint forEvent:(UIEvent *)event;
-(void) dispatchTouchEvent:(UIView *)theView toPosition:(CGPoint)position;
-(void) dispatchTouchEndEvent:(UIView *)theView toPosition:(CGPoint)position;
@end


@implementation MyView

#define GROW_ANIMATION_DURATION_SECONDS 0.15    // Determines how fast a piece size grows when it is moved.
#define SHRINK_ANIMATION_DURATION_SECONDS 0.15  // Determines how fast a piece size shrinks when a piece stops moving.

@synthesize firstPieceView;
@synthesize secondPieceView;
@synthesize thirdPieceView;
@synthesize touchPhaseText;
@synthesize touchInfoText;
@synthesize touchTrackingText;
@synthesize touchInstructionsText;
@synthesize piecesOnTop;
@synthesize startTouchPosition;

#pragma mark -
#pragma mark === Setting up and tearing down ===
#pragma mark

/*
 Unarchives the view that is stored in the xib file.
 Initializes the main view and adds three subviews, each of which have the appearance of a piece that the user can move.
 Also creates two text labels, one that displays the touch phase, and the other that displays touch information (such as swipe, number of touches). 
*/
- (id)initWithCoder:(NSCoder*)coder 
{
	if (self = [super initWithCoder:coder]) {
		
		self.backgroundColor =[UIColor blackColor];
		
		// Set up the ability to track multiple touches.
		[self setMultipleTouchEnabled:YES];
		
		// Create the three views -- each calculates its own frame based on the size of its image
		firstPieceView = [self newPieceViewWithImageNamed:@"CyanSquare.png" atPostion:self.center];
		[self addSubview:firstPieceView];
		
		secondPieceView = [self newPieceViewWithImageNamed:@"YellowSquare.png" atPostion:CGPointMake(self.center.x -100.,self.center.y -100.)];
		[self addSubview:secondPieceView];
		
		thirdPieceView = [self newPieceViewWithImageNamed:@"MagentaSquare.png" atPostion:CGPointMake(self.center.x + 100.,self.center.y + 100.0)];
		[self addSubview:thirdPieceView];	
		
		// Set up a text label to show the touch phase.
		// Create and inialize the label.
		touchPhaseText = [self newLabelWithOffset:(self.frame.origin.y + 25) numberOfLines: 1];
		// Set the default text that shows on startup.
		touchPhaseText.text = @"Touches lets you observe touch";
		// Add the label as a subview.
	    [self addSubview:touchPhaseText];
		
		// Create and inialite a text label to show the number of touches tracked.
		touchTrackingText = [self newLabelWithOffset:(self.frame.origin.y + 45) numberOfLines: 1];	
		// Set the default text that shows on startup.
		touchTrackingText.text = @"phases and multiple taps.";
		[self addSubview:touchTrackingText];
		
		// Create and inialite a text label to show multiple tap information.
		touchInfoText = [self newLabelWithOffset:(self.frame.origin.y + 65) numberOfLines: 1];

		// Add the label as a subview.
		[self addSubview:touchInfoText];
		
		
		
		// Create and intiate a label to provide instructions to the user when pieces overlap.
		touchInstructionsText = [self newLabelWithOffset:(self.frame.size.height - 45) numberOfLines: 2];
		[self addSubview:touchInstructionsText];
	}
	return self;
}

/*
 Allocates and initializes a label object. 
 Sets characteristics to default values.
*/
-(UILabel *) newLabelWithOffset:(float)offset numberOfLines:(NSUInteger) lines
{
	float textHeight = 20.0;	
	UILabel *label =  [[UILabel alloc] initWithFrame:CGRectMake(self.frame.origin.x + 10.0, offset, self.frame.size.width - 20.0, textHeight * lines)];
	// Set the font size, text color, background color, and alignment.
	label.font = [UIFont systemFontOfSize:18.0];
	label.textColor = [UIColor lightTextColor];
	label.backgroundColor = [UIColor clearColor];
	label.textAlignment = UITextAlignmentCenter;
    // Set the number of lines
	label.numberOfLines = lines;
	if (lines > 1)
		// Set the linebreak mode if there is more than one line.
		label.lineBreakMode = UILineBreakModeWordWrap;
	// Initialize as an empty string
	label.text = @"";
	return label;
	
}


/*
 Allocates and initializes a piece view object. 
 Sets characteristics to default values.
*/
-(UIImageView *)newPieceViewWithImageNamed:(NSString *)imageName atPostion:(CGPoint)centerPoint
{
	UIImage *image = [UIImage imageNamed:imageName];
	UIImageView *theView = [[UIImageView alloc] initWithImage:image];
	// Set the center of the view.
	theView.center = centerPoint;
	// Set alpha so it is slightly transparent to allow seeing pieces move over each other.
	theView.alpha = 0.9;
	// Disable user interaction for this view. You must do this if you want to handle touches for more than one object at at time.
	// You'll get events for the superview, and then dispatch them to the appropriate subview in the touch handling methods.
	theView.userInteractionEnabled = NO;