UI进阶--手势识别

为了完成手势识别，必须借助于手势识别器----UIGestureRecognizer

利用UIGestureRecognizer，能轻松识别用户在某个view上面做的一些常见手势

UIGestureRecognizer是一个抽象类，定义了所有手势的基本行为，使用它的子类才能处理具体的手势

UITapGestureRecognizer(敲击)

UIPinchGestureRecognizer(捏合，用于缩放)

UIPanGestureRecognizer(拖拽)

UISwipeGestureRecognizer(轻扫)

UIRotationGestureRecognizer(旋转)

UILongPressGestureRecognizer(长按)

 

手势识别的状态：

typedef NS_ENUM(NSInteger, UIGestureRecognizerState) {
    // 没有触摸事件发生，所有手势识别的默认状态
    UIGestureRecognizerStatePossible,
    // 一个手势已经开始但尚未改变或者完成时
    UIGestureRecognizerStateBegan,
    // 手势状态改变
    UIGestureRecognizerStateChanged,
    // 手势完成
    UIGestureRecognizerStateEnded,
    // 手势取消，恢复至Possible状态
    UIGestureRecognizerStateCancelled, 
    // 手势失败，恢复至Possible状态
    UIGestureRecognizerStateFailed,
    // 识别到手势识别
    UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded
};

 

每一个手势识别器的用法都差不多，比如UITapGestureRecognizer的使用步骤如下

//创建手势识别器对象
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] init];
//设置手势识别器对象的具体属性
// 连续敲击2次
tap.numberOfTapsRequired = 2;
// 需要2根手指一起敲击
tap.numberOfTouchesRequired = 2;
//添加手势识别器到对应的view上
[self.iconView addGestureRecognizer:tap];
//监听手势的触发
[tap addTarget:self action:@selector(tapIconView:)];

敲击手势--UITapGestureRecognizer
①敲击手势对象相关属性

@property (nonatomic) NSUInteger  numberOfTapsRequired; //敲击次数，默认是1
@property (nonatomic) NSUInteger  numberOfTouchesRequired;//多点敲击，默认是1

②代理方法 "实现左半边才接收触摸事件"

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch;//是否接受触摸事件 

 

长按手势--UILongPressGestureRecognizer
长按手势对象相关属性

@property (nonatomic) CFTimeInterval minimumPressDuration; //长按的时间，默认是0.5. 
@property (nonatomic) CGFloat allowableMovement; //触摸点周围多远的距离内长按有效，默认是50(CGPoint)

 

轻扫手势--UISwipeGestureRecognizer
轻扫手势对象相关属性
 

@property(nonatomic) UISwipeGestureRecognizerDirection direction; //轻扫的方向,是一个枚举型

typedef NS_OPTIONS(NSUInteger, UISwipeGestureRecognizerDirection) {
    UISwipeGestureRecognizerDirectionRight = 1 << 0,//向右轻扫,默认为向右轻扫
    UISwipeGestureRecognizerDirectionLeft  = 1 << 1,//向左轻扫
    UISwipeGestureRecognizerDirectionUp    = 1 << 2,//向上轻扫
    UISwipeGestureRecognizerDirectionDown  = 1 << 3//向下轻扫
};

 

捏合手势--UIPinchGestureRecognizer
捏合手势对象相关属性

@property (nonatomic)          CGFloat scale; //缩放比例，是一个累加的过程,如果想不累加，把scale设为1即可
//例子：
- (void)pinvhView:(UIPinchGestureRecognizer *)pinch {
    self.pinView.transform = CGAffineTransformScale(self.pinView.transform,pinch.scale,pinch.scale);
    pinch.scale = 1;
}

 
旋转手势--UIRotationGestureRecognizer
①旋转手势对象相关属性

@property (nonatomic)          CGFloat rotation;  //旋转角度，也是一个累加的过程，如果想它不累加，把其设为0即可。
//例子
- (void)rotationView:(UIRotationGestureRecognizer *)pinch {
    self.pinView.transform = CGAffineTransformRotate(self.pinView.transform,pinch.rotation);
    pinch.rotation = 0;
}

②如果捏合和旋转想同时使用，设置其中一个手势的代理并实现代理的一个方法

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer;//实现该方法，返回YES即可，允许跟其它手势一起发生

拖拽手势--UIPanGestureRecognizer

拖拽手势对象相关方法和属性：

@property (nonatomic)          NSUInteger minimumNumberOfTouches;   // default is 1. the minimum number of touches required to match
@property (nonatomic)          NSUInteger maximumNumberOfTouches;   // default is UINT_MAX. the maximum number of touches that can be down

- (CGPoint)translationInView:(UIView *)view;                        // translation in the coordinate system of the specified view
- (void)setTranslation:(CGPoint)translation inView:(UIView *)view;

- (CGPoint)velocityInView:(UIView *)view;                           // velocity of the pan in pixels/second in the coordinate system of the specified view