手势识别在 iOS 中非常重要,他极大地提高了移动设备的使用便捷性。iOS 系统在 3.2 以后,他提供了一些常用的手势(UIGestureRecognizer 的子类),开发者可以直接使用他们进行手势操作。
手势类型(他们都继承自UIGestureRecognizer,而UIGestureRecognizer继承自NSObject)
UIPanGestureRecognizer(拖动)
UIPinchGestureRecognizer(捏合)
UIRotationGestureRecognizer(旋转)
UITapGestureRecognizer(点按)
UILongPressGestureRecognizer(长按)
UISwipeGestureRecognizer(轻扫)
- 代码实战的时候,通常继承 UIGestureRecognizer 类,实现自定义手势(手势识别器类)一般设计成单利对象。因为事件传递如果是通过Block或者是代理,那么如果超过识别器的生命周期,手势将不能正常响应(具体看github代码)
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;
-(void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event;
- 手势的互斥的原则
1.手势识别是具有互斥的原则的,比如单击和双击,如果它识别出一种手势,其后的手势将不被识别。所以对于关联手势,要做特殊处理以帮助程序甄别,应该把当前手势归结到哪一类手势里面。
2.比如,单击和双击并存时,如果不做处理,它就只能发送出单击的消息。为了能够识别出双击手势,就需要做一个特殊处理逻辑,即先判断手势是否是双击,在双击失效的情况下作为单击手势处理。使用
[A requireGestureRecognizerToFail:B]函数,它可以指定当A手势发生时,即便A已经滿足条件了,也不会立刻触发,会等到指定的手势B确定失败之后才触发。
[tapOne requireGestureRecognizerToFail:tapTow];
- 如果手势和scrollview一起使用就要防止只相应scrollView事件
scrollView.canCancelContentTouches=NO;
scrollView.delaysContentTouches=NO;
- 手势的几种状态
typedef NS_ENUM(NSInteger, UIGestureRecognizerState) {
UIGestureRecognizerStatePossible,
UIGestureRecognizerStateBegan,
UIGestureRecognizerStateChanged,
UIGestureRecognizerStateEnded,
UIGestureRecognizerStateCancelled,
UIGestureRecognizerStateFailed,
UIGestureRecognizerStateRecognized
UIGestureRecognizerStateEnded
};
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- 手势经常用的属性
@property(nullable,nonatomic,weak) id <UIGestureRecognizerDelegate> delegate;
@property(nonatomic, getter=isEnabled) BOOL enabled;
@property(nullable, nonatomic,readonly) UIView *view;
-(CGPoint)locationInView:(nullable UIView*)view;
-(NSUInteger)numberOfTouches;
-(CGPoint)locationOfTouch:(NSUInteger)touchIndex inView:(nullable UIView*)view;
-(void)requireGestureRecognizerToFail:(UIGestureRecognizer *)otherGestureRecognizer;
-(CGPoint)translationInView:(nullable UIView *)view;
相对重要的BOOL属性
@property(nonatomic) BOOL cancelsTouchesInView;
当这个属性设置为YES时,如果识别到了手势,
系统将会发送touchesCancelled:withEvent:消息在其时间传递链上,
终止触摸事件的传递,
设置为NO,则不会终止事件的传递
@property(nonatomic) BOOL delaysTouchesBegan;
这个属性设置手势识别结束后,是立刻发送touchesEnded消息到事件传递链或者等待一个很短的时间后,
如果没有接收到新的手势识别任务,再发送。
UIGestureRecognizerDelegate
前面我们提到过关于手势对象的协议代理,通过代理的回调,我们可以进行自定义手势,也可以处理一些复杂的手势关系,其中方法如下:
//手指触摸屏幕后回调的方法,返回NO则不再进行手势识别,方法触发等
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch;
//开始进行手势识别时调用的方法,返回NO则结束,不再触发手势
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer;
//是否支持多时候触发,返回YES,则可以多个手势一起触发方法,返回NO则为互斥
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer;
//下面这个两个方法也是用来控制手势的互斥执行的
//这个方法返回YES,第一个手势和第二个互斥时,第一个会失效
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRequireFailureOfGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer NS_AVAILABLE_IOS(7_0);
//这个方法返回YES,第一个和第二个互斥时,第二个会失效
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer NS_AVAILABLE_IOS(7_0);
UIGestureRecognizer的子类介绍
一、UITapGestureRecognizer(tap点按)
- 点击作为最常用手势,用于按下或选择一个控件或条目(类似于普通的鼠标点击);
- tap手势属于离散型手势,特点是:一旦识别就无法取消,而且只会调用一次手势操作事件(初始化手势时指定的回调方法)
代码
UITapGestureRecognizer *tapOne = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tapWithOne:)];
tapOne.delegate = self;
[self.view addGestureRecognizer:tapOne];
[tapOne setNumberOfTouchesRequired:1];
[tapOne setNumberOfTapsRequired:1];
UITapGestureRecognizer *tapTow = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tapWithTow:)];
tapTow.delegate = self;
[tapOne setNumberOfTouchesRequired:1];
tapTow.numberOfTapsRequired = 2;
[self.view addGestureRecognizer:tapTow];
[tapOne requireGestureRecognizerToFail:tapTow];
-(void)tapWithOne: (UITapGestureRecognizer *)tapOne {
NSLog(@"被点击了一次");
}
-(void)tapWithTow: (UITapGestureRecognizer *)tapTow {
NSLog(@"被点击了两次");
}
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二、 UILongPressGestureRecognizer(长按手势 )
1.属性:
@property (nonatomic) NSUInteger numberOfTapsRequired;
@property (nonatomic) NSUInteger numberOfTouchesRequired ;
@property (nonatomic) CFTimeInterval minimumPressDuration;
@property (nonatomic) CGFloat allowableMovement;
三、UIPinchGestureRecognizer(捏合手势 )
1.属性:
@property (nonatomic) CGFloat scale;
@property (nonatomic,readonly) CGFloat velocity;
四、UILongPressGestureRecognizer(长按)
长按手势一定需要和UIGestureRecognizer类的state属性进行配合使用,即通过不同状态state下,实现不同的功能。
1. 基本属性和方法
maximumNumberOfTouches:
minimumPressDuration:
-translationInView:
-velocityInView:
五、UIRotationGestureRecognizer(旋转)
属性:
@property (nonatomic) CGFloat rotation;
@property (nonatomic,readonly) CGFloat velocity;
**六、UIPanGestureRecognizer(拖动手势)**
属性:
//最小的拖动范围
@property (nonatomic) NSUInteger minimumNumberOfTouches __TVOS_PROHIBITED;
//最大拖动范围
@property (nonatomic) NSUInteger maximumNumberOfTouches __TVOS_PROHIBITED;
//获取移动后相对与view的坐标系的偏移量
- (CGPoint)translationInView:(nullable UIView *)view;
//获取移动后的坐标
- (void)setTranslation:(CGPoint)translation inView:(nullable UIView *)view;
**七、UISwipeGestureRecognizer**
>需要注意的是如果想要实现多方向清扫,要创建多个清扫手势对象
属性
//最小的扫动距离
@property(nonatomic) NSUInteger numberOfTouchesRequired;
//轻扫的方向默认UISwipeGestureRecognizerDirectionRight
@property(nonatomic) UISwipeGestureRecognizerDirection direction;
“`
手势相关的基本知识就是这些了,如果有什么问题欢迎大家指正,如果有兴趣,大家可以下载,手势工具类源码查看