iOS开发笔记之多点触控（三）调用UITouch对象方法——locationInView，多点移动多个对象

- (void)viewDidLoad{    [super viewDidLoad];    self.view.multipleTouchEnabled = TRUE;    // Do any additional setup after loading the view, typically from a nib.    _view1 = [[UIView alloc] initWithFrame:CGRectMake(0, 40, 40, 40)];    _view1.backgroundColor = [UIColor blueColor];    [self.view addSubview:_view1];        _view2 = [[UIView alloc] initWithFrame:CGRectMake(0, self.view.frame.size.height - 60, 40, 40)];    _view2.backgroundColor = [UIColor yellowColor];    [self.view addSubview:_view2];}-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event //首次在屏幕上检测到触摸时调用{    NSLog(@"touchesBegan");    for (UITouch *touch in touches)    {//        NSLog(@" - %p",touch);        //获取根视图内触摸点的point        CGPoint touchPoint = [touch locationInView:self.view];        //约束两个view的活动范围        if (touchPoint.y < self.view.frame.size.height/2)        {            _view1.center = CGPointMake(touchPoint.x, _view1.center.y);        }else        {            _view2.center = CGPointMake(touchPoint.x, _view2.center.y);        }    }}//以上对触摸进行了初始化，并未处理沿着屏幕移动的触摸。所以，只需要在touchesMoved方法里调用touchesBegan的处理方法来改写移动球拍的逻辑即可。-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event //如果触摸移动到了新的位置则会调用此方法{    NSLog(@"touchesMoved");    for (UITouch *touch in touches)    {//        NSLog(@" - %p",touch);        [self touchesBegan:touches withEvent:event];    }}-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event//当触摸离开屏幕调用此方法{    NSLog(@"touchesEnded");    for (UITouch *touch in touches)    {        NSLog(@" - %p",touch);    }}-(void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event//如系统决定取消此次触摸，那可能就不调用touchesEnded方法了，在这种情况下会调用touchesCancelled方法{    NSLog(@"touchesCancelled");    for (UITouch *touch in touches)    {        NSLog(@" - %p",touch);    }}