1、UIGestureRecognizer介绍
手势识别在iOS上非常重要,手势操作移动设备的重要特征,极大的增加了移动设备使用便捷性。
iOS系统在3.2以后,为方便开发这使用一些常用的手势,提供了UIGestureRecognizer类。手势识别UIGestureRecognizer类是个抽象类,下面的子类是具体的手势,开发这可以直接使用这些手势识别。
- UITapGestureRecognizer
- UIPinchGestureRecognizer
- UIRotationGestureRecognizer
- UISwipeGestureRecognizer
- UIPanGestureRecognizer
- UILongPressGestureRecognizer
上面的手势对应的操作是:
- Tap(点一下)
- Pinch(二指往內或往外拨动,平时经常用到的缩放)
- Rotation(旋转)
- Swipe(滑动,快速移动)
- Pan (拖移,慢速移动)
- LongPress(长按)
UIGestureRecognizer的继承关系如下:
2、使用手势的步骤
使用手势很简单,分为两步:
- 创建手势实例。当创建手势时,指定一个回调方法,当手势开始,改变、或结束时,回调方法被调用。
- 添加到需要识别的View中。每个手势只对应一个View,当屏幕触摸在View的边界内时,如果手势和预定的一样,那就会回调方法。
ps:一个手势只能对应一个View,但是一个View可以有多个手势。
建议在真机上运行这些手势,模拟器操作不太方便,可能导致你认为手势失效。
3、Pan 拖动手势:
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UIImageView *snakeImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snake.png"]]; snakeImageView.frame = CGRectMake(50, 50, 100, 160); UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)]; [snakeImageView addGestureRecognizer:panGestureRecognizer]; [self.view setBackgroundColor:[UIColor whiteColor]]; [self.view addSubview:snakeImageView]; |
新建一个ImageView,然后添加手势
回调方法:
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- (void) handlePan:(UIPanGestureRecognizer*) recognizer { CGPoint translation = [recognizer translationInView:self.view]; recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x, recognizer.view.center.y + translation.y); [recognizer setTranslation:CGPointZero inView:self.view]; } |
4、Pinch缩放手势
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UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(handlePinch:)];<p class="p1">[<span class="s1">snakeImageView</span> <span class="s2">addGestureRecognizer</span>:pinchGestureRecognizer];</p> |
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- (void) handlePinch:(UIPinchGestureRecognizer*) recognizer { recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale); recognizer.scale = 1; } |
5、Rotation旋转手势
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