Secret Code Sample

gistfile1.m

@interface TouchableView : UIView 
{
  CGPoint touchBeganPoint;
  CGPoint lastUpdatedPoint;
  NSArray *colorArray;
  NSInteger colorIndex;
}

@end

#import "TouchableView.h"

#define MAX_TAP_DELTA 1.0f

@implementation TouchableView

- (id)initWithFrame:(CGRect)frame 
{
  if (![super initWithFrame:frame]) return nil;
  
  colorArray = [[NSArray alloc] initWithObjects:[UIColor greenColor],
                [UIColor blueColor], [UIColor redColor], nil];
  colorIndex = 0;
  [self setBackgroundColor:[colorArray objectAtIndex:colorIndex]];
  
  touchBeganPoint = CGPointZero;
  [self setUserInteractionEnabled:YES];
  [self setMultipleTouchEnabled:YES];
  return self;
}

- (void)dealloc 
{
  [colorArray release], colorArray = nil;
  [super dealloc];
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
  NSLog(@"%@:%s touches %u", [self class], _cmd, [touches count]);
  UITouch *beginTouch = [touches anyObject];
  touchBeganPoint = [beginTouch locationInView:[self window]];
  lastUpdatedPoint = [beginTouch locationInView:[self window]];
}

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
  NSLog(@"%@:%s touches %u", [self class], _cmd, [touches count]);
  touchBeganPoint = CGPointZero;
  lastUpdatedPoint = CGPointZero;
}

- (void)throbAnimationDidStop:(NSString*)animationID 
                     finished:(NSNumber*)finished 
                      context:(void*)context 
{
	
	[UIView beginAnimations:nil context:NULL];
	[UIView setAnimationDuration:0.15];
	[self setTransform:CGAffineTransformMakeScale(1.1, 1.1)];
	[UIView commitAnimations];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
  NSLog(@"%@:%s touches %u", [self class], _cmd, [touches count]);
  CGPoint touchPoint = [[touches anyObject] locationInView:[self window]];
  float deltaX = touchPoint.x - touchBeganPoint.x;
  float deltaY = touchPoint.y - touchBeganPoint.y;
  touchBeganPoint = CGPointZero;
  lastUpdatedPoint = CGPointZero;
  
  if (deltaX > MAX_TAP_DELTA && deltaY > MAX_TAP_DELTA) {
    return;
  }

  ++colorIndex;
  if (colorIndex >= [colorArray count]) colorIndex = 0;
  
  CGColorRef color = [[colorArray objectAtIndex:colorIndex] CGColor];
  
  [UIView beginAnimations:nil context:NULL];
	[UIView setAnimationDelegate:self];
	[UIView setAnimationDuration:0.15f];
  
	[UIView setAnimationDidStopSelector:@selector(throbAnimationDidStop:finished:context:)];
	[self setTransform:CGAffineTransformMakeScale(1.4, 1.4)];
  
  [[self layer] setBackgroundColor:color];
  
  [UIView commitAnimations];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
  NSLog(@"%@:%s touches %u", [self class], _cmd, [touches count]);
  [UIView beginAnimations:nil context:NULL];
  CGPoint touchPoint = [[touches anyObject] locationInView:[self window]];
  float deltaX = touchPoint.x - lastUpdatedPoint.x;
  float deltaY = touchPoint.y - lastUpdatedPoint.y;
  
  float newCenterX = [[self layer] position].x + deltaX;
  float newCenterY = [[self layer] position].y + deltaY;
  
  CGPoint center = CGPointMake(newCenterX, newCenterY);
  [[self layer] setPosition:center];
  lastUpdatedPoint = touchPoint;
  [UIView commitAnimations];
}

@end