iOS 手勢操作：拖動、捏合、旋轉、點按、長按、輕掃、自定義

1、UIGestureRecognizer 介紹

手勢識別在 iOS 中非常重要，他極大地提高了移動設備的使用便捷性。

iOS 系統在 3.2 以后，他提供了一些常用的手勢（UIGestureRecognizer 的子類），開發者可以直接使用他們進行手勢操作。

• UIPanGestureRecognizer（拖動）
• UIPinchGestureRecognizer（捏合）
• UIRotationGestureRecognizer（旋轉）
• UITapGestureRecognizer（點按）
• UILongPressGestureRecognizer（長按）
• UISwipeGestureRecognizer（輕掃）
</ul>

另外，可以通過繼承 UIGestureRecognizer 類，實現自定義手勢（手勢識別器類）。

PS：自定義手勢時，需要 #import <UIKit/UIGestureRecognizerSubclass.h>，一般需實現如下方法：

1 - (void)reset;
2 
3 - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
4 - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;
5 - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;
6 - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event;
7 //以上方法在分類 UIGestureRecognizer (UIGestureRecognizerProtected) 中聲明，更多方法聲明請自行查看

UIGestureRecognizer 的繼承關系如下：



2、手勢狀態

在六種手勢識別中，只有一種手勢是離散型手勢，他就是 UITapGestureRecognizer。

離散型手勢的特點就是：一旦識別就無法取消，而且只會調用一次手勢操作事件（初始化手勢時指定的回調方法）。

換句話說其他五種手勢是連續型手勢，而連續型手勢的特點就是：會多次調用手勢操作事件，而且在連續手勢識別后可以取消手勢。從下圖可以看出兩者調用操作事件的次數是不同的：



手勢狀態枚舉如下：

1 typedef NS_ENUM(NSInteger, UIGestureRecognizerState) {
2     UIGestureRecognizerStatePossible,   // 尚未識別是何種手勢操作（但可能已經觸發了觸摸事件），默認狀態
3     UIGestureRecognizerStateBegan,      // 手勢已經開始，此時已經被識別，但是這個過程中可能發生變化，手勢操作尚未完成
4     UIGestureRecognizerStateChanged,    // 手勢狀態發生轉變
5     UIGestureRecognizerStateEnded,      // 手勢識別操作完成（此時已經松開手指）
6     UIGestureRecognizerStateCancelled,  // 手勢被取消，恢復到默認狀態
7     UIGestureRecognizerStateFailed,     // 手勢識別失敗，恢復到默認狀態
8     UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded // 手勢識別完成，同UIGestureRecognizerStateEnded
9 };

• 對于離散型手勢 UITapGestureRecgnizer 要么被識別，要么失敗，點按（假設點按次數設置為1，并且沒有添加長按手勢）下去一次不松開則此時什么也不會發生，松開手指立即識別并調用操作事件，并且狀態為3（已完成）。
• 但是連續型手勢要復雜一些，就拿旋轉手勢來說，如果兩個手指點下去不做任何操作，此時并不能識別手勢（因為我們還沒旋轉）但是其實已經觸發了觸摸 開始事件，此時處于狀態0；如果此時旋轉會被識別，也就會調用對應的操作事件，同時狀態變成1（手勢開始），但是狀態1只有一瞬間；緊接著狀態變為2（因 為我們的旋轉需要持續一會），并且重復調用操作事件（如果在事件中打印狀態會重復打印2）；松開手指，此時狀態變為3，并調用1次操作事件。
</ul>

3、使用手勢的步驟

使用手勢很簡單，分為三步：

1. 創建手勢識別器對象實例。創建時，指定一個回調方法，當手勢開始，改變、或結束時，執行回調方法。
2. 設置手勢識別器對象實例的相關屬性（可選部分）
3. 添加到需要識別的 View 中。每個手勢只對應一個 View，當屏幕觸摸在 View 的邊界內時，如果手勢和預定的一樣，那就會執行回調方法。
</ol>

PS：一個手勢只能對應一個 View，但是一個 View 可以有多個手勢。建議在真機上測試這些手勢，模擬器操作不太方便，可能導致認為手勢失效的情況。（模擬器測試捏合和旋轉手勢時，按住 option 鍵，再用觸摸板或鼠標操作）

4、舉例說明

功能描述：

附加到兩個圖片視圖 UIImageView 的有『拖動』、『捏合』、『旋轉』、『點按』；

而『輕掃』和『自定義手勢 KMGestureRecognizer』附加在根視圖 UIView 中。

1. 拖動：進行當前圖片視圖位置移動
2. 捏合：進行當前圖片視圖縮放
3. 旋轉：進行當前圖片視圖角度旋轉
4. 點按：雙擊恢復當前圖片視圖的縮放、角度旋轉、不透明度
5. 長按：設置當前圖片視圖的不透明度為0.7
6. 輕掃：左右輕掃設置兩個圖片視圖為居中，同時以垂直居中的特定偏移量定位
7. 自定義手勢：撓癢功能，左右掃動共3次或以上，設置兩個圖片視圖為居中，同時以水平居中的特定偏移量定位
</ol>

效果如下：



KMGestureRecognizer.h

 1 #import <UIKit/UIKit.h>
 2 
 3 typedef NS_ENUM(NSUInteger, Direction) {
 4     DirectionUnknown,
 5     DirectionLeft,
 6     DirectionRight
 7 };
 8 
 9 @interface KMGestureRecognizer : UIGestureRecognizer
10 @property (assign, nonatomic) NSUInteger tickleCount; //撓癢次數
11 @property (assign, nonatomic) CGPoint currentTickleStart; //當前撓癢開始坐標位置
12 @property (assign, nonatomic) Direction lastDirection; //最后一次撓癢方向
13 
14 @end

KMGestureRecognizer.m

 1 #import "KMGestureRecognizer.h"
 2 #import <UIKit/UIGestureRecognizerSubclass.h>
 3 
 4 @implementation KMGestureRecognizer
 5 #define kMinTickleSpacing 20.0
 6 #define kMaxTickleCount 3
 7 
 8 - (void)reset {
 9     _tickleCount = 0;
10     _currentTickleStart = CGPointZero;
11     _lastDirection = DirectionUnknown;
12     
13     if (self.state == UIGestureRecognizerStatePossible) {
14         self.state = UIGestureRecognizerStateFailed;
15     }
16 }
17 
18 - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
19     UITouch *touch = [touches anyObject];
20     _currentTickleStart = [touch locationInView:self.view]; //設置當前撓癢開始坐標位置
21 }
22 
23 - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
24     //『當前撓癢開始坐標位置』和『移動后坐標位置』進行 X 軸值比較，得到是向左還是向右移動
25     UITouch *touch = [touches anyObject];
26     CGPoint tickleEnd = [touch locationInView:self.view];
27     CGFloat tickleSpacing = tickleEnd.x - _currentTickleStart.x;
28     Direction currentDirection = tickleSpacing < 0 ? DirectionLeft : DirectionRight;
29     
30     //移動的 X 軸間距值是否符合要求，足夠大
31     if (ABS(tickleSpacing) >= kMinTickleSpacing) {
32         //判斷是否有三次不同方向的動作，如果有則手勢結束，將執行回調方法
33         if (_lastDirection == DirectionUnknown ||
34             (_lastDirection == DirectionLeft && currentDirection == DirectionRight) ||
35             (_lastDirection == DirectionRight && currentDirection == DirectionLeft)) {
36             _tickleCount++;
37             _currentTickleStart = tickleEnd;
38             _lastDirection = currentDirection;
39             
40             if (_tickleCount >= kMaxTickleCount && self.state == UIGestureRecognizerStatePossible) {
41                 self.state = UIGestureRecognizerStateEnded;
42                 //NSLog(@"自定義手勢成功，將執行回調方法");
43             }
44         }
45     }
46 }
47 
48 - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
49     [self reset];
50 }
51 
52 - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {
53     [self reset];
54 }
55 
56 @end

ViewController.h

1 #import <UIKit/UIKit.h>
2 #import "KMGestureRecognizer.h"
3 
4 @interface ViewController : UIViewController
5 @property (strong, nonatomic) UIImageView *imgV;
6 @property (strong, nonatomic) UIImageView *imgV2;
7 @property (strong, nonatomic) KMGestureRecognizer *customGestureRecognizer;
8 
9 @end

ViewController.m

  1 #import "ViewController.h"
  2 
  3 @interface ViewController ()
  4 - (void)handlePan:(UIPanGestureRecognizer *)recognizer;
  5 - (void)handlePinch:(UIPinchGestureRecognizer *)recognizer;
  6 - (void)handleRotation:(UIRotationGestureRecognizer *)recognizer;
  7 - (void)handleTap:(UITapGestureRecognizer *)recognizer;
  8 - (void)handleLongPress:(UILongPressGestureRecognizer *)recognizer;
  9 - (void)handleSwipe:(UISwipeGestureRecognizer *)recognizer;
 10 - (void)handleCustomGestureRecognizer:(KMGestureRecognizer *)recognizer;
 11 
 12 - (void)bindPan:(UIImageView *)imgVCustom;
 13 - (void)bindPinch:(UIImageView *)imgVCustom;
 14 - (void)bindRotation:(UIImageView *)imgVCustom;
 15 - (void)bindTap:(UIImageView *)imgVCustom;
 16 - (void)bindLongPress:(UIImageView *)imgVCustom;
 17 - (void)bindSwipe;
 18 - (void)bingCustomGestureRecognizer;
 19 - (void)layoutUI;
 20 @end
 21 
 22 @implementation ViewController
 23 
 24 - (void)viewDidLoad {
 25     [super viewDidLoad];
 26     
 27     [self layoutUI];
 28 }
 29 
 30 - (void)didReceiveMemoryWarning {
 31     [super didReceiveMemoryWarning];
 32     // Dispose of any resources that can be recreated.
 33 }
 34 
 35 #pragma mark - 處理手勢操作
 36 /**
 37  *  處理拖動手勢
 38  *
 39  *  @param recognizer 拖動手勢識別器對象實例
 40  */
 41 - (void)handlePan:(UIPanGestureRecognizer *)recognizer {
 42     //視圖前置操作
 43     [recognizer.view.superview bringSubviewToFront:recognizer.view];
 44     
 45     CGPoint center = recognizer.view.center;
 46     CGFloat cornerRadius = recognizer.view.frame.size.width / 2;
 47     CGPoint translation = [recognizer translationInView:self.view];
 48     //NSLog(@"%@", NSStringFromCGPoint(translation));
 49     recognizer.view.center = CGPointMake(center.x + translation.x, center.y + translation.y);
 50     [recognizer setTranslation:CGPointZero inView:self.view];
 51     
 52     if (recognizer.state == UIGestureRecognizerStateEnded) {
 53         //計算速度向量的長度，當他小于200時，滑行會很短
 54         CGPoint velocity = [recognizer velocityInView:self.view];
 55         CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y));
 56         CGFloat slideMult = magnitude / 200;
 57         //NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult); //e.g. 397.973175, slideMult: 1.989866
 58         
 59         //基于速度和速度因素計算一個終點
 60         float slideFactor = 0.1 * slideMult;
 61         CGPoint finalPoint = CGPointMake(center.x + (velocity.x * slideFactor),
 62                                          center.y + (velocity.y * slideFactor));
 63         //限制最小［cornerRadius］和最大邊界值［self.view.bounds.size.width - cornerRadius］，以免拖動出屏幕界限
 64         finalPoint.x = MIN(MAX(finalPoint.x, cornerRadius),
 65                            self.view.bounds.size.width - cornerRadius);
 66         finalPoint.y = MIN(MAX(finalPoint.y, cornerRadius),
 67                            self.view.bounds.size.height - cornerRadius);
 68         
 69         //使用 UIView 動畫使 view 滑行到終點
 70         [UIView animateWithDuration:slideFactor*2
 71                               delay:0
 72                             options:UIViewAnimationOptionCurveEaseOut
 73                          animations:^{
 74                              recognizer.view.center = finalPoint;
 75                          }
 76                          completion:nil];
 77     }
 78 }
 79 
 80 /**
 81  *  處理捏合手勢
 82  *
 83  *  @param recognizer 捏合手勢識別器對象實例
 84  */
 85 - (void)handlePinch:(UIPinchGestureRecognizer *)recognizer {
 86     CGFloat scale = recognizer.scale;
 87     recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, scale, scale); //在已縮放大小基礎下進行累加變化；區別于：使用 CGAffineTransformMakeScale 方法就是在原大小基礎下進行變化
 88     recognizer.scale = 1.0;
 89 }
 90 
 91 /**
 92  *  處理旋轉手勢
 93  *
 94  *  @param recognizer 旋轉手勢識別器對象實例
 95  */
 96 - (void)handleRotation:(UIRotationGestureRecognizer *)recognizer {
 97     recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation);
 98     recognizer.rotation = 0.0;
 99 }
100 
101 /**
102  *  處理點按手勢
103  *
104  *  @param recognizer 點按手勢識別器對象實例
105  */
106 - (void)handleTap:(UITapGestureRecognizer *)recognizer {
107     UIView *view = recognizer.view;
108     view.transform = CGAffineTransformMakeScale(1.0, 1.0);
109     view.transform = CGAffineTransformMakeRotation(0.0);
110     view.alpha = 1.0;
111 }
112 
113 /**
114  *  處理長按手勢
115  *
116  *  @param recognizer 點按手勢識別器對象實例
117  */
118 - (void)handleLongPress:(UILongPressGestureRecognizer *)recognizer {
119     //長按的時候，設置不透明度為0.7
120     recognizer.view.alpha = 0.7;
121 }
122 
123 /**
124  *  處理輕掃手勢
125  *
126  *  @param recognizer 輕掃手勢識別器對象實例
127  */
128 - (void)handleSwipe:(UISwipeGestureRecognizer *)recognizer {
129     //代碼塊方式封裝操作方法
130     void (^positionOperation)() = ^() {
131         CGPoint newPoint = recognizer.view.center;
132         newPoint.y -= 20.0;
133         _imgV.center = newPoint;
134         
135         newPoint.y += 40.0;
136         _imgV2.center = newPoint;
137     };
138     
139     //根據輕掃方向，進行不同控制
140     switch (recognizer.direction) {
141         case UISwipeGestureRecognizerDirectionRight: {
142             positionOperation();
143             break;
144         }
145         case UISwipeGestureRecognizerDirectionLeft: {
146             positionOperation();
147             break;
148         }
149         case UISwipeGestureRecognizerDirectionUp: {
150             break;
151         }
152         case UISwipeGestureRecognizerDirectionDown: {
153             break;
154         }
155     }
156 }
157 
158 /**
159  *  處理自定義手勢
160  *
161  *  @param recognizer 自定義手勢識別器對象實例
162  */
163 - (void)handleCustomGestureRecognizer:(KMGestureRecognizer *)recognizer {
164     //代碼塊方式封裝操作方法
165     void (^positionOperation)() = ^() {
166         CGPoint newPoint = recognizer.view.center;
167         newPoint.x -= 20.0;
168         _imgV.center = newPoint;
169         
170         newPoint.x += 40.0;
171         _imgV2.center = newPoint;
172     };
173     
174     positionOperation();
175 }
176 
177 
178 #pragma mark - 綁定手勢操作
179 /**
180  *  綁定拖動手勢
181  *
182  *  @param imgVCustom 綁定到圖片視圖對象實例
183  */
184 - (void)bindPan:(UIImageView *)imgVCustom {
185     UIPanGestureRecognizer *recognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self
186                                                                                  action:@selector(handlePan:)];
187     [imgVCustom addGestureRecognizer:recognizer];
188 }
189 
190 /**
191  *  綁定捏合手勢
192  *
193  *  @param imgVCustom 綁定到圖片視圖對象實例
194  */
195 - (void)bindPinch:(UIImageView *)imgVCustom {
196     UIPinchGestureRecognizer *recognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self
197                                                                                      action:@selector(handlePinch:)];
198     [imgVCustom addGestureRecognizer:recognizer];
199     //[recognizer requireGestureRecognizerToFail:imgVCustom.gestureRecognizers.firstObject];
200 }
201 
202 /**
203  *  綁定旋轉手勢
204  *
205  *  @param imgVCustom 綁定到圖片視圖對象實例
206  */
207 - (void)bindRotation:(UIImageView *)imgVCustom {
208     UIRotationGestureRecognizer *recognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self
209                                                                                            action:@selector(handleRotation:)];
210     [imgVCustom addGestureRecognizer:recognizer];
211 }
212 
213 /**
214  *  綁定點按手勢
215  *
216  *  @param imgVCustom 綁定到圖片視圖對象實例
217  */
218 - (void)bindTap:(UIImageView *)imgVCustom {
219     UITapGestureRecognizer *recognizer = [[UITapGestureRecognizer alloc] initWithTarget:self
220                                                                                  action:@selector(handleTap:)];
221     //使用一根手指雙擊時，才觸發點按手勢識別器
222     recognizer.numberOfTapsRequired = 2;
223     recognizer.numberOfTouchesRequired = 1;
224     [imgVCustom addGestureRecognizer:recognizer];
225 }
226 
227 /**
228  *  綁定長按手勢
229  *
230  *  @param imgVCustom 綁定到圖片視圖對象實例
231  */
232 - (void)bindLongPress:(UIImageView *)imgVCustom {
233     UILongPressGestureRecognizer *recognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPress:)];
234     recognizer.minimumPressDuration = 0.5; //設置最小長按時間；默認為0.5秒
235     [imgVCustom addGestureRecognizer:recognizer];
236 }
237 
238 /**
239  *  綁定輕掃手勢；支持四個方向的輕掃，但是不同的方向要分別定義輕掃手勢
240  */
241 - (void)bindSwipe {
242     //向右輕掃手勢
243     UISwipeGestureRecognizer *recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self
244                                                                                      action:@selector(handleSwipe:)];
245     recognizer.direction = UISwipeGestureRecognizerDirectionRight; //設置輕掃方向；默認是 UISwipeGestureRecognizerDirectionRight，即向右輕掃
246     [self.view addGestureRecognizer:recognizer];
247     [recognizer requireGestureRecognizerToFail:_customGestureRecognizer]; //設置以自定義撓癢手勢優先識別
248     
249     //向左輕掃手勢
250     recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self
251                                                            action:@selector(handleSwipe:)];
252     recognizer.direction = UISwipeGestureRecognizerDirectionLeft;
253     [self.view addGestureRecognizer:recognizer];
254     [recognizer requireGestureRecognizerToFail:_customGestureRecognizer]; //設置以自定義撓癢手勢優先識別
255 }
256 
257 /**
258  *  綁定自定義撓癢手勢；判斷是否有三次不同方向的動作，如果有則手勢結束，將執行回調方法
259  */
260 - (void)bingCustomGestureRecognizer {
261     //當 recognizer.state 為 UIGestureRecognizerStateEnded 時，才執行回調方法 handleCustomGestureRecognizer:
262     
263     //_customGestureRecognizer = [KMGestureRecognizer new];
264     _customGestureRecognizer = [[KMGestureRecognizer alloc] initWithTarget:self
265                                                                     action:@selector(handleCustomGestureRecognizer:)];
266     [self.view addGestureRecognizer:_customGestureRecognizer];
267 }
268 
269 - (void)layoutUI {
270     //圖片視圖 _imgV
271     UIImage *img = [UIImage imageNamed:@"Emoticon_tusiji_icon"];
272     CGFloat cornerRadius = img.size.width;
273     _imgV = [[UIImageView alloc] initWithImage:img];
274     _imgV.frame = CGRectMake(20.0, 20.0,
275                              cornerRadius * 2, cornerRadius * 2);
276     _imgV.userInteractionEnabled = YES;
277     _imgV.layer.masksToBounds = YES;
278     _imgV.layer.cornerRadius = cornerRadius;
279     _imgV.layer.borderWidth = 2.0;
280     _imgV.layer.borderColor = [UIColor grayColor].CGColor;
281     [self.view addSubview:_imgV];
282     
283     //圖片視圖 _imgV2
284     img = [UIImage imageNamed:@"Emoticon_tusiji_icon2"];
285     cornerRadius = img.size.width;
286     _imgV2 = [[UIImageView alloc] initWithImage:img];
287     _imgV2.frame = CGRectMake(20.0, 40.0 + _imgV.frame.size.height,
288                               cornerRadius * 2, cornerRadius * 2);
289     _imgV2.userInteractionEnabled = YES;
290     _imgV2.layer.masksToBounds = YES;
291     _imgV2.layer.cornerRadius = cornerRadius;
292     _imgV2.layer.borderWidth = 2.0;
293     _imgV2.layer.borderColor = [UIColor orangeColor].CGColor;
294     [self.view addSubview:_imgV2];
295     
296     
297     [self bindPan:_imgV];
298     [self bindPinch:_imgV];
299     [self bindRotation:_imgV];
300     [self bindTap:_imgV];
301     [self bindLongPress:_imgV];
302     
303     [self bindPan:_imgV2];
304     [self bindPinch:_imgV2];
305     [self bindRotation:_imgV2];
306     [self bindTap:_imgV2];
307     [self bindLongPress:_imgV2];
308     
309     //為了處理手勢識別優先級的問題，這里需先綁定自定義撓癢手勢
310     [self bingCustomGestureRecognizer];
311     [self bindSwipe];
312 }
313 
314 @end

來源：KenmuHuang