你真的了解UIGestureRecognizer嗎?

今天在封裝一個(gè)功能的時(shí)候，碰到了多個(gè)手勢(shì)之間的識(shí)別問(wèn)題，需要實(shí)現(xiàn)UIGestureRecognizerDelegate協(xié)議中的[gestureRecognizer:shouldRecognizeSimultaneouslyWithGestureRecognizer:]方法來(lái)實(shí)現(xiàn)多個(gè)手勢(shì)識(shí)別器的共同識(shí)別。因此也借此整理下關(guān)于UIGestureRecognizer相關(guān)知識(shí)點(diǎn)。

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一. UIGestureRecognizer的定義

UIGestureRecognizer是一個(gè)抽象基類，定義了實(shí)現(xiàn)底層手勢(shì)識(shí)別行為的編程接口，使得繼承它的子類能處理具體的手勢(shì)。

//當(dāng)前手勢(shì)狀態(tài)
typedef NS_ENUM(NSInteger, UIGestureRecognizerState) {
    // 尚未識(shí)別是何種手勢(shì)操作（但可能已經(jīng)觸發(fā)了觸摸事件），默認(rèn)狀態(tài)
    UIGestureRecognizerStatePossible,   
    // 手勢(shì)已經(jīng)開始，此時(shí)已經(jīng)被識(shí)別，但是這個(gè)過(guò)程中可能發(fā)生變化，手勢(shì)操作尚未完成
    UIGestureRecognizerStateBegan,     
    // 手勢(shì)狀態(tài)發(fā)生改變
    UIGestureRecognizerStateChanged, 
    // 手勢(shì)識(shí)別操作完成（此時(shí)已經(jīng)松開手指）  
    UIGestureRecognizerStateEnded, 
    // 手勢(shì)被取消，恢復(fù)到默認(rèn)狀態(tài)   
    UIGestureRecognizerStateCancelled, 
    // 手勢(shì)識(shí)別失敗，恢復(fù)到默認(rèn)狀態(tài)
    UIGestureRecognizerStateFailed,    
    // 手勢(shì)識(shí)別完成，同end
    UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded 
};

</br>

 @interface UIGestureRecognizer : NSObject

//創(chuàng)建一個(gè)手勢(shì)對(duì)象并添加觸發(fā)事件
- (instancetype)initWithTarget:(nullable id)target action:(nullable SEL)action NS_DESIGNATED_INITIALIZER; 
//給一個(gè)手勢(shì)對(duì)象添加監(jiān)聽事件
- (void)addTarget:(id)target action:(SEL)action;   
//移除一個(gè)手勢(shì)的監(jiān)聽事件
- (void)removeTarget:(nullable id)target action:(nullable SEL)action; 
//獲取當(dāng)前手勢(shì)狀態(tài)
@property(nonatomic,readonly) UIGestureRecognizerState state;  
//委托
@property(nullable,nonatomic,weak) id <UIGestureRecognizerDelegate> delegate; 
//手勢(shì)識(shí)別是否可用
@property(nonatomic, getter=isEnabled) BOOL enabled;  
//獲取手勢(shì)觸摸的View視圖 只讀
@property(nullable, nonatomic,readonly) UIView *view;         
//是否取消觸摸控件的響應(yīng)
默認(rèn)為YES，這種情況下當(dāng)手勢(shì)識(shí)別器識(shí)別到觸摸之后，會(huì)發(fā)送touchesCancelled給觸摸到的控件以取消控件view對(duì)touch的響應(yīng)，
這個(gè)時(shí)候只有手勢(shì)識(shí)別器響應(yīng)touch，當(dāng)設(shè)置成NO時(shí)，手勢(shì)識(shí)別器識(shí)別到觸摸之后不會(huì)發(fā)送touchesCancelled給控件，
這個(gè)時(shí)候手勢(shì)識(shí)別器和控件view均響應(yīng)touch。
注意：手勢(shì)識(shí)別和觸摸事件是同時(shí)存在的，只是因?yàn)閠ouchesCancelled導(dǎo)致觸摸事件失效、
@property(nonatomic) BOOL cancelsTouchesInView; 
  
//是否延遲發(fā)送觸摸事件給觸摸到的控件
默認(rèn)是NO，這種情況下當(dāng)發(fā)生一個(gè)觸摸時(shí)，手勢(shì)識(shí)別器先捕捉到到觸摸，然后發(fā)給觸摸到的控件，兩者各自做出響應(yīng)。如果設(shè)置為YES，手勢(shì)識(shí)別器在識(shí)別的過(guò)程中（注意是識(shí)別過(guò)程），不會(huì)將觸摸發(fā)給觸摸到的控件，即控件不會(huì)有任何觸摸事件。只有在識(shí)別失敗之后才會(huì)將觸摸事件發(fā)給觸摸到的控件，這種情況下控件view的響應(yīng)會(huì)延遲約0.15ms。
@property(nonatomic) BOOL delaysTouchesBegan;     

//如果觸摸識(shí)別失敗是否立即結(jié)束本次手勢(shì)識(shí)別的觸摸事件
@property(nonatomic) BOOL delaysTouchesEnded;        

//指定一個(gè)手勢(shì)需要另一個(gè)手勢(shì)執(zhí)行失敗才會(huì)執(zhí)行，同時(shí)觸發(fā)多個(gè)手勢(shì)使用其中一個(gè)手勢(shì)的解決辦法
有時(shí)手勢(shì)是相關(guān)聯(lián)的，如單機(jī)和雙擊，點(diǎn)擊和長(zhǎng)按，點(diǎn)下去瞬間可能只會(huì)識(shí)別到單擊無(wú)法識(shí)別其他，該方法可以指定某一個(gè) 手勢(shì)，即便自己已經(jīng)滿足條件了，也不會(huì)立刻觸發(fā)，會(huì)等到該指定的手勢(shì)確定失敗之后才觸發(fā)
- (void)requireGestureRecognizerToFail:(UIGestureRecognizer *)otherGestureRecognizer;

//獲取當(dāng)前觸摸在指定視圖上的點(diǎn)
- (CGPoint)locationInView:(nullable UIView*)view;                               

//獲取觸摸手指數(shù)
- (NSUInteger)numberOfTouches;                                         

//多指觸摸的觸摸點(diǎn)相對(duì)于指定視圖的位置
- (CGPoint)locationOfTouch:(NSUInteger)touchIndex inView:(nullable UIView*)view; 

@end

二. 關(guān)于UIGestureRecognizerDelegate代理的內(nèi)容

@protocol UIGestureRecognizerDelegate <NSObject>
@optional

//開始進(jìn)行手勢(shì)識(shí)別時(shí)調(diào)用的方法，返回NO則結(jié)束識(shí)別，不再觸發(fā)手勢(shì)，用處：可以在控件指定的位置使用手勢(shì)識(shí)別
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer;

//是否支持多手勢(shì)觸發(fā)，返回YES，則可以多個(gè)手勢(shì)一起觸發(fā)方法，返回NO則為互斥
是否允許多個(gè)手勢(shì)識(shí)別器共同識(shí)別，一個(gè)控件的手勢(shì)識(shí)別后是否阻斷手勢(shì)識(shí)別繼續(xù)向下傳播，默認(rèn)返回NO；
如果為YES，響應(yīng)者鏈上層對(duì)象觸發(fā)手勢(shì)識(shí)別后，如果下層對(duì)象也添加了手勢(shì)并成功識(shí)別也會(huì)繼續(xù)執(zhí)行，否則上層對(duì)象識(shí)別后則不再繼續(xù)傳播
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer;

// 這個(gè)方法返回YES，第一個(gè)手勢(shì)和第二個(gè)互斥時(shí)，第一個(gè)會(huì)失效
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRequireFailureOfGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer NS_AVAILABLE_IOS(7_0);

//這個(gè)方法返回YES，第一個(gè)和第二個(gè)互斥時(shí)，第二個(gè)會(huì)失效
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer NS_AVAILABLE_IOS(7_0);

//手指觸摸屏幕后回調(diào)的方法，返回NO則不再進(jìn)行手勢(shì)識(shí)別，方法觸發(fā)等
此方法在window對(duì)象在有觸摸事件發(fā)生時(shí)，調(diào)用gesture recognizer的touchesBegan:withEvent:方法之前調(diào)用，
如果返回NO,則gesture recognizer不會(huì)看到此觸摸事件。(默認(rèn)情況下為YES)
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch;
@end

</br>

常用知識(shí):

//是否同時(shí)支持多種手勢(shì)
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer     shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer{
  return YES;
}

//是否允許開始點(diǎn)擊
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer{
return YES;
}
//設(shè)置點(diǎn)擊的范圍
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch{
//獲取當(dāng)前的觸摸點(diǎn)
  CGPoint curp = [touch locationInView:self.imageView];
  if (curp.x <= self.imageView.bounds.size.width*0.5) {
      return NO;
  }else{
      return YES;
  }
}

UITapGestureRecognizer和UIButton的點(diǎn)擊事件沖突的解決辦法：

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch{    
if ([touch.view isKindOfClass:[UIButton class]])    { 
       return NO;   
      }   
       return YES;
  }

三. UIGestureRecognizer的子類

UITapGestureRecognizer（輕觸，點(diǎn)按）
UILongPressGestureRecognizer（長(zhǎng)按）
UISwipeGestureRecognizer（輕掃手勢(shì)）
UIRotationGestureRecognizer（旋轉(zhuǎn)手勢(shì)）
UIPanGestureRecognizer（拖拽手勢(shì)）
UIPinchGestureRecognizer（捏合手勢(shì)，縮放用）

1. UITapGestureRecognizer（輕觸，點(diǎn)按）

@interface UITapGestureRecognizer : UIGestureRecognizer

//設(shè)置能識(shí)別到手勢(shì)的最少的輕觸次數(shù)（默認(rèn)為1）
@property (nonatomic) NSUInteger  numberOfTapsRequired;     
//設(shè)置能識(shí)別到手勢(shì)的最少的手指的個(gè)數(shù)（默認(rèn)為1） 
@property (nonatomic) NSUInteger  numberOfTouchesRequired;  
@end

實(shí)例:

// 創(chuàng)建一個(gè)手勢(shì)對(duì)象
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapAction:)];
// 設(shè)置能識(shí)別到手勢(shì)的最少的輕觸次數(shù)
tap.numberOfTapsRequired = 3;
// 設(shè)置能識(shí)別到手勢(shì)的最少的手指的個(gè)數(shù)
tap.numberOfTouchesRequired = 2;
//把手勢(shì)對(duì)象添加到對(duì)應(yīng)的控件中
[self.imgView addGestureRecognizer:tap];

2：UILongPressGestureRecognizer（長(zhǎng)按手勢(shì)）

 @interface UILongPressGestureRecognizer : UIGestureRecognizer
//設(shè)置能識(shí)別到手勢(shì)的最少的輕觸次數(shù)（默認(rèn)為1）
@property (nonatomic) NSUInteger numberOfTapsRequired;     
//設(shè)置能識(shí)別到手勢(shì)的最少的手指的個(gè)數(shù)（默認(rèn)為1） 
@property (nonatomic) NSUInteger numberOfTouchesRequired;   
//設(shè)置能識(shí)別到長(zhǎng)按手勢(shì)的最短的長(zhǎng)按時(shí)間，單位：秒，默認(rèn)為0.5
@property (nonatomic) CFTimeInterval minimumPressDuration; 
//設(shè)置長(zhǎng)按時(shí)允許移動(dòng)的最大距離，單位：像素，默認(rèn)為10像素
@property (nonatomic) CGFloat allowableMovement;           
@end

實(shí)例:

UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPressAction:)];
// 設(shè)置能識(shí)別到長(zhǎng)按手勢(shì)的最小的長(zhǎng)按時(shí)間
longPress.minimumPressDuration = 0.5;
// "容錯(cuò)的范圍"
longPress.allowableMovement  = 10;
// 把長(zhǎng)按手勢(shì)添加到對(duì)應(yīng)的控件中
[self.imgView addGestureRecognizer:longPress];

3：UISwipeGestureRecognizer（輕掃手勢(shì)）

typedef NS_OPTIONS(NSUInteger, UISwipeGestureRecognizerDirection) {
    UISwipeGestureRecognizerDirectionRight = 1 << 0,  //向右滑
    UISwipeGestureRecognizerDirectionLeft  = 1 << 1,  //向左滑
    UISwipeGestureRecognizerDirectionUp    = 1 << 2,  //向上滑
    UISwipeGestureRecognizerDirectionDown  = 1 << 3  //向下滑
};

@interface UISwipeGestureRecognizer : UIGestureRecognizer 
//最少觸摸手指?jìng)€(gè)數(shù)，默認(rèn)為1
@property(nonatomic) NSUInteger                        numberOfTouchesRequired; 
//設(shè)置輕掃手勢(shì)支持的方向，默認(rèn)為向右滑
@property(nonatomic) UISwipeGestureRecognizerDirection direction;               
@end

實(shí)例

UISwipeGestureRecognizer *swipeLeft = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipeAction:)];
swipeLeft.direction = UISwipeGestureRecognizerDirectionLeft;
[self.imgView addGestureRecognizer:swipeLeft];

4：UIRotationGestureRecognizer（旋轉(zhuǎn)手勢(shì)）

@interface UIRotationGestureRecognizer : UIGestureRecognizer
//旋轉(zhuǎn)的角度
@property (nonatomic)          CGFloat rotation;  
//旋轉(zhuǎn)速度，單位：度/秒、         
@property (nonatomic,readonly) CGFloat velocity;           
@end

實(shí)例:

//為圖片框添加一個(gè)旋轉(zhuǎn)手勢(shì)
UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotateAction:)];rotation.delegate = self;
[self.imgView addGestureRecognizer:rotation];


// 旋轉(zhuǎn)手勢(shì)的監(jiān)聽方法
- (void)rotateAction:(UIRotationGestureRecognizer *)recognizer {
    // 在原來(lái)的基礎(chǔ)上, 累加多少度
    recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation);
    // 每次旋轉(zhuǎn)完畢后將rotation的值, 恢復(fù)到0的位置.recognizer.rotation = 0;
}

5：UIPanGestureRecognizer（拖拽手勢(shì)）

@interface UIPanGestureRecognizer : UIGestureRecognizer 
//設(shè)置觸發(fā)拖拽最少手指數(shù)，默認(rèn)為1
@property (nonatomic)          NSUInteger minimumNumberOfTouches;   
//設(shè)置觸發(fā)拖拽最多手指數(shù)，默認(rèn)為 UINT_MAX 無(wú)限大
@property (nonatomic)          NSUInteger maximumNumberOfTouches;   
//獲取當(dāng)前拖拽位置
- (CGPoint)translationInView:(nullable UIView *)view;                        
//設(shè)置當(dāng)前拖拽位置
- (void)setTranslation:(CGPoint)translation inView:(nullable UIView *)view;
//設(shè)置拖拽速度，單位：像素/秒
- (CGPoint)velocityInView:(nullable UIView *)view;                          
@end

實(shí)例

UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panAction:)];
[self.imgView addGestureRecognizer:pan];


// 拖拽手勢(shì)的監(jiān)聽方法
- (void)panAction:(UIPanGestureRecognizer *)recognizer {
    // 1. 獲取手指拖拽的時(shí)候, 平移的值
    CGPoint translation = [recognizer translationInView:recognizer.view];
    // 2. 讓當(dāng)前控件做響應(yīng)的平移
    recognizer.view.transform = CGAffineTransformTranslate(recognizer.view.transform, translation.x, translation.y);
    // 3. 每次平移手勢(shì)識(shí)別完畢后, 讓平移的值不要累加
    [recognizer setTranslation:CGPointZero inView:recognizer.view];
}

6：UIPinchGestureRecognizer（捏合手勢(shì)，縮放用）

@interface UIPinchGestureRecognizer : UIGestureRecognizer 

//設(shè)置縮放比例
@property (nonatomic)          CGFloat scale;     
//獲取捏合速度，單位：縮放比/秒         
@property (nonatomic,readonly) CGFloat velocity;            
@end

實(shí)例

UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinchAction:)];
pinch.delegate = self;
[self.imgView addGestureRecognizer:pinch];



// 捏合手勢(shì)監(jiān)聽方法
- (void)pinchAction:(UIPinchGestureRecognizer *)recognizer {
    recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale,     recognizer.scale);
    recognizer.scale = 1.0;
}

四. 最后

送上一張圖片:

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