iOS手势简介
iOS的手势，就是程序识别到你在屏幕上做的一些手势动作，做出反应。常见的手势有
- UITapGestureRecognizer
- UISwipeGestureRecognizer
- UIRotationGestureRecognizer
- UIPanGestureRecognizer
- UIPinchGestureRecognizer
- UILongPressGestureRecognizer
其中tap还有单击、双击，Swipe还有向上、下、左、右等区分。
识别这些手势，对每种手势做个反应，没啥难度。下面总结了5个步骤，和几个特殊的地方。
使用过程分5步
step1: 声明和初始化一个手势识别器
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| UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTap:)];
UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDoubleTap:)];
UITapGestureRecognizer *twoFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTwoFingerTap:)];
UISwipeGestureRecognizer *swipeLeft = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipe:)];
UISwipeGestureRecognizer *swipeRight = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipe:)];
UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(handleRotation:)];
UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)];
UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(handlePinch:)];
UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPress:)];
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step2：对手势识别器进行属性设定
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| [doubleTap setNumberOfTapsRequired:2];
[twoFingerTap setNumberOfTouchesRequired:2];
[swipeLeft setNumberOfTouchesRequired:1];
[swipeLeft setDirection:UISwipeGestureRecognizerDirectionLeft];
[swipeRight setNumberOfTouchesRequired:1];
[swipeRight setDirection:UISwipeGestureRecognizerDirectionRight];
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step3：把手势识别器加到view中去
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| [self.view addGestureRecognizer:singleTap];
[self.view addGestureRecognizer:doubleTap];
[self.view addGestureRecognizer:twoFingerTap];
[self.view addGestureRecognizer:swipeLeft];
[self.view addGestureRecognizer:swipeRight];
[self.view addGestureRecognizer:rotation];
[self.view addGestureRecognizer:pan];
[self.view addGestureRecognizer:pinch];
[self.view addGestureRecognizer:longPress];
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step4：出现冲突时，要设定优先识别顺序
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| [singleTap requireGestureRecognizerToFail:doubleTap];
[singleTap requireGestureRecognizerToFail:twoFingerTap];
[pan requireGestureRecognizerToFail:swipeRight];
[pan requireGestureRecognizerToFail:swipeLeft];
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step5：去实现处理扑捉到手势之后的动作
填写各个处理函数，如：
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| - (void)handleSingleTap:(UITapGestureRecognizer *)gestureRecognizer
- (void)handleDoubleTap:(UITapGestureRecognizer *)gestureRecognizer
- (void)handleTwoFingerTap:(UITapGestureRecognizer *)gestureRecognizer
- (void)handleSwipe:(UISwipeGestureRecognizer *)gestureRecognizer
- (void)handleRotation:(UIRotationGestureRecognizer *)gestureRecognizer
- (void)handlePan:(UIPanGestureRecognizer *)gestureRecognizer
- (void)handlePinch:(UIPinchGestureRecognizer *)gestureRecognizer
- (void)handleLongPress:(UILongPressGestureRecognizer *)gestureRecognizer
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测试代码
在下面测试代码中，实现了六个手势的处理。
代码下载
在实现的时候，有几个需要注意的地方：
注意几个小地方
区分单击双击、滑动（Swipe）和拖拽（Pan）
在识别单击双击时，逻辑上应该只有判断非双击时，才判定为单击，否则永远都只会判断为单击；在识别滑动和拖拽时也是一样，应该先判断是否是swipe，不是则才是拖拽，否则都只会识别拖拽。实现方式见上面Step4，使用requireGestureRecognizerToFail方法。
向每个方向滑动（Swipe）都是一个独立的手势
如果你想接受向多个方向的滑动，对每个方向都要声明一个手势，专门代表这个方向的滑动。向左向右就是两个，加上向上向下就是4个。
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| UISwipeGestureRecognizer *swipeLeft = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipe:)];
UISwipeGestureRecognizer *swipeRight = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipe:)];
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然后，你在扑捉到滑动手势之后的处理函数中，去判断UISwipeGestureRecognizer *类型的recognizer.direction是属于：
- UISwipeGestureRecognizerDirectionLeft
- UISwipeGestureRecognizerDirectionUp
- UISwipeGestureRecognizerDirectionDown
- UISwipeGestureRecognizerDirectionRight
中的哪个，然后再进一步去处理。