iOS開發之UIGestureRecognizer

一：首先查看一下關於UIGestureRecognizer的定義

//當前手勢狀態
typedef NS_ENUM(NSInteger, UIGestureRecognizerState) {
    //還沒有識別是何種手勢操做（但可能已經觸發了觸摸事件），默認狀態
    UIGestureRecognizerStatePossible,   
    //手勢已經開始，此時已經被識別，可是這個過程當中可能發生變化，手勢操做還沒有完成
    UIGestureRecognizerStateBegan,     
    //手勢狀態發生改變
    UIGestureRecognizerStateChanged, 
    // 手勢識別操做完成（此時已經鬆開手指）  
    UIGestureRecognizerStateEnded, 
    //手勢被取消，恢復到默認狀態   
    UIGestureRecognizerStateCancelled, 
    //手勢識別失敗，恢復到默認狀態
    UIGestureRecognizerStateFailed,    
    //手勢識別完成，同end
    UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded 
};

NS_CLASS_AVAILABLE_IOS(3_2) @interface UIGestureRecognizer : NSObject

//建立一個手勢對象並添加觸發事件
- (instancetype)initWithTarget:(nullable id)target action:(nullable SEL)action NS_DESIGNATED_INITIALIZER; 
//給一個手勢對象添加監聽事件
- (void)addTarget:(id)target action:(SEL)action;   
//移除一個手勢的監聽事件
- (void)removeTarget:(nullable id)target action:(nullable SEL)action; 
//獲取當前手勢狀態
@property(nonatomic,readonly) UIGestureRecognizerState state;  
//委託
@property(nullable,nonatomic,weak) id <UIGestureRecognizerDelegate> delegate; 
//手勢識別是否可用
@property(nonatomic, getter=isEnabled) BOOL enabled;  
//獲取手勢觸摸的View視圖 只讀
@property(nullable, nonatomic,readonly) UIView *view;         
//是否取消觸摸控件的響應
默認爲YES，這種狀況下當手勢識別器識別到觸摸以後，會發送touchesCancelled給觸摸到的控件以取消控件view對touch的響應，這個時候只有手勢識別器響應touch，當設置成NO時，手勢識別器識別到觸摸以後不會發送touchesCancelled給控件，這個時候手勢識別器和控件view均響應touch。
注意：手勢識別和觸摸事件是同時存在的，只是由於touchesCancelled致使觸摸事件失效、
@property(nonatomic) BOOL cancelsTouchesInView; 
      
//是否延遲發送觸摸事件給觸摸到的控件
默認是NO，這種狀況下當發生一個觸摸時，手勢識別器先捕捉到到觸摸，而後發給觸摸到的控件，二者各自作出響應。若是設置爲YES，手勢識別器在識別的過程當中（注意是識別過程），不會將觸摸發給觸摸到的控件，即控件不會有任何觸摸事件。只有在識別失敗以後纔會將觸摸事件發給觸摸到的控件，這種狀況下控件view的響應會延遲約0.15ms。
@property(nonatomic) BOOL delaysTouchesBegan;     
  
//若是觸摸識別失敗是否當即結束本次手勢識別的觸摸事件
@property(nonatomic) BOOL delaysTouchesEnded;        

//指定一個手勢須要另外一個手勢執行失敗纔會執行，同時觸發多個手勢使用其中一個手勢的解決辦法
有時手勢是相關聯的，如單機和雙擊，點擊和長按，點下去瞬間可能只會識別到單擊沒法識別其餘，該方法能夠指定某一個 手勢，即使本身已經知足條件了，也不會馬上觸發，會等到該指定的手勢肯定失敗以後才觸發
- (void)requireGestureRecognizerToFail:(UIGestureRecognizer *)otherGestureRecognizer;

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

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

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

@end

UIGestureRecognizer是一個抽象類，定義了全部手勢的基本行爲，使用它的子類才能處理具體的手勢

知識點1：關於UIGestureRecognizer的子類以下（下面這些纔是咱們日常會直接運用到的類）：

UITapGestureRecognizer（輕觸，點按）
UILongPressGestureRecognizer（長按）
UISwipeGestureRecognizer（輕掃手勢）
UIRotationGestureRecognizer（旋轉手勢）
UIPanGestureRecognizer（拖拽手勢）
UIPinchGestureRecognizer（捏合手勢，縮放用）

實例以下：

//拖拽手勢
UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
[tagButton addGestureRecognizer:pan];


- (void)pan:(UIPanGestureRecognizer *)pan
{
             
｝

//給視圖增長點擊動做

UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tapHandle:)];
[self.view addGestureRecognizer:tap];


-(void)tapHandle:(UITapGestureRecognizer*)tap
{
    
}

二：關於UIGestureRecognizerDelegate代理的內容

@protocol UIGestureRecognizerDelegate <NSObject>
@optional

//開始進行手勢識別時調用的方法，返回NO則結束識別，再也不觸發手勢，用處：能夠在控件指定的位置使用手勢識別
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer;

//是否支持多手勢觸發，返回YES，則能夠多個手勢一塊兒觸發方法，返回NO則爲互斥
是否容許多個手勢識別器共同識別，一個控件的手勢識別後是否阻斷手勢識別繼續向下傳播，默認返回NO；若是爲YES，響應者鏈上層對象觸發手勢識別後，若是下層對象也添加了手勢併成功識別也會繼續執行，不然上層對象識別後則再也不繼續傳播
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer;

// 這個方法返回YES，第一個手勢和第二個互斥時，第一個會失效
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRequireFailureOfGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer NS_AVAILABLE_IOS(7_0);

//這個方法返回YES，第一個和第二個互斥時，第二個會失效
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer NS_AVAILABLE_IOS(7_0);

//手指觸摸屏幕後回調的方法，返回NO則再也不進行手勢識別，方法觸發等
此方法在window對象在有觸摸事件發生時，調用gesture recognizer的touchesBegan:withEvent:方法以前調用，若是返回NO,則gesture recognizer不會看到此觸摸事件。(默認狀況下爲YES)
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch;

@end

知識點1：

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

//是否容許開始點擊
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer{
return YES;
}
//設置點擊的範圍
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch{
//獲取當前的觸摸點
  CGPoint curp = [touch locationInView:self.imageView];
  if (curp.x <= self.imageView.bounds.size.width*0.5) {
      return NO;
  }else{

      return YES;
  }
}

知識點2：UITapGestureRecognizer和UIButton的點擊事件衝突的解決辦法

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

三：關於UIGestureRecognizer的子類知識

1:UITapGestureRecognizer（輕觸，點按）

NS_CLASS_AVAILABLE_IOS(3_2) @interface UITapGestureRecognizer : UIGestureRecognizer

//設置能識別到手勢的最少的輕觸次數（默認爲1）
@property (nonatomic) NSUInteger  numberOfTapsRequired;     
//設置能識別到手勢的最少的手指的個數（默認爲1） 
@property (nonatomic) NSUInteger  numberOfTouchesRequired;  
@end

知識點1：實例代碼以下

// 建立一個手勢對象
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapAction:)];
// 設置能識別到手勢的最少的輕觸次數
tap.numberOfTapsRequired = 3;
// 設置能識別到手勢的最少的手指的個數
tap.numberOfTouchesRequired = 2;
//把手勢對象添加到對應的控件中
[self.imgView addGestureRecognizer:tap];

2：UILongPressGestureRecognizer（長按手勢）

NS_CLASS_AVAILABLE_IOS(3_2) @interface UILongPressGestureRecognizer : UIGestureRecognizer
//設置能識別到手勢的最少的輕觸次數（默認爲1）
@property (nonatomic) NSUInteger numberOfTapsRequired;     
//設置能識別到手勢的最少的手指的個數（默認爲1） 
@property (nonatomic) NSUInteger numberOfTouchesRequired;   
//設置能識別到長按手勢的最短的長按時間，單位：秒，默認爲0.5
@property (nonatomic) CFTimeInterval minimumPressDuration; 
//設置長按時容許移動的最大距離，單位：像素，默認爲10像素
@property (nonatomic) CGFloat allowableMovement;           

@end

知識點1：實例代碼以下

UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPressAction:)];
// 設置能識別到長按手勢的最小的長按時間
longPress.minimumPressDuration = 0.5;
// "容錯的範圍"
longPress.allowableMovement  = 10;
// 把長按手勢添加到對應的控件中
[self.imgView addGestureRecognizer:longPress];

3：UISwipeGestureRecognizer（輕掃手勢）

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
};

NS_CLASS_AVAILABLE_IOS(3_2) @interface UISwipeGestureRecognizer : UIGestureRecognizer 
//最少觸摸手指個數，默認爲1
@property(nonatomic) NSUInteger                        numberOfTouchesRequired; 
//設置輕掃手勢支持的方向，默認爲向右滑
@property(nonatomic) UISwipeGestureRecognizerDirection direction;               

@end

知識點1：實例代碼以下

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

4：UIRotationGestureRecognizer（旋轉手勢）

NS_CLASS_AVAILABLE_IOS(3_2) @interface UIRotationGestureRecognizer : UIGestureRecognizer
//旋轉的角度
@property (nonatomic)          CGFloat rotation;  
//旋轉速度，單位：度/秒、         
@property (nonatomic,readonly) CGFloat velocity;           

@end

知識點1：實例代碼以下

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


// 旋轉手勢的監聽方法
- (void)rotateAction:(UIRotationGestureRecognizer *)recognizer {
// 在原來的基礎上, 累加多少度
recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation);
// 每次旋轉完畢後將rotation的值, 恢復到0的位置.recognizer.rotation = 0;
}

5：UIPanGestureRecognizer（拖拽手勢）

NS_CLASS_AVAILABLE_IOS(3_2) @interface UIPanGestureRecognizer : UIGestureRecognizer 
//設置觸發拖拽最少手指數，默認爲1
@property (nonatomic)          NSUInteger minimumNumberOfTouches;   
//設置觸發拖拽最多手指數，默認爲 UINT_MAX 無限大
@property (nonatomic)          NSUInteger maximumNumberOfTouches;   
//獲取當前拖拽位置
- (CGPoint)translationInView:(nullable UIView *)view;                        
//設置當前拖拽位置
- (void)setTranslation:(CGPoint)translation inView:(nullable UIView *)view;
//設置拖拽速度，單位：像素/秒
- (CGPoint)velocityInView:(nullable UIView *)view;                          

@end

知識點1：實例代碼

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


// 拖拽手勢的監聽方法
- (void)panAction:(UIPanGestureRecognizer *)recognizer {
// 1. 獲取手指拖拽的時候, 平移的值
CGPoint translation = [recognizer translationInView:recognizer.view];
// 2. 讓當前控件作響應的平移
recognizer.view.transform = CGAffineTransformTranslate(recognizer.view.transform, translation.x, translation.y);
// 3. 每次平移手勢識別完畢後, 讓平移的值不要累加
[recognizer setTranslation:CGPointZero inView:recognizer.view];
}

6：UIPinchGestureRecognizer（捏合手勢，縮放用）

NS_CLASS_AVAILABLE_IOS(3_2) @interface UIPinchGestureRecognizer : UIGestureRecognizer 

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

@end

知識點1：實例代碼

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



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