1、UIGestureRecognizer介紹

手勢識別在iOS上非常重要种柑，手勢操作移動設(shè)備的重要特征，極大的增加了移動設(shè)備使用便捷性匹耕。
iOS系統(tǒng)在3.2以后聚请，為方便開發(fā)這使用一些常用的手勢，提供了UIGestureRecognizer類泌神。手勢識別UIGestureRecognizer類是個抽象類良漱，下面的子類是具體的手勢，開發(fā)這可以直接使用這些手勢識別欢际。

UITapGestureRecognizer  
UIPinchGestureRecognizer
UIRotationGestureRecognizer
UISwipeGestureRecognizer
UIPanGestureRecognizer
UILongPressGestureRecognizer

上面的手勢對應(yīng)的操作是：

Tap（點一下）
Pinch（二指往內(nèi)或往外撥動母市，平時經(jīng)常用到的縮放）
Rotation（旋轉(zhuǎn)）
Swipe（滑動，快速移動）
Pan （拖移损趋，慢速移動）
 LongPress（長按）

UIGestureRecognizer的繼承關(guān)系如下：

1361893916_7845.png

2患久、使用手勢的步驟

使用手勢很簡單，分為兩步：

• 創(chuàng)建手勢實例浑槽。當創(chuàng)建手勢時蒋失，指定一個回調(diào)方法，當手勢開始桐玻，改變篙挽、或結(jié)束時，回調(diào)方法被調(diào)用镊靴。
• 添加到需要識別的View中铣卡。每個手勢只對應(yīng)一個View，當屏幕觸摸在View的邊界內(nèi)時偏竟，如果手勢和預(yù)定的一樣煮落，那就會回調(diào)方法。

ps：一個手勢只能對應(yīng)一個View踊谋，但是一個View可以有多個手勢蝉仇。
建議在真機上運行這些手勢,模擬器操作不太方便，可能導(dǎo)致你認為手勢失效

3殖蚕、Pan 拖動手勢：

UIImageView *snakeImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snake.png"]];  
snakeImageView.frame = CGRectMake(50, 50, 100, 160);  
UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc]  
                                                initWithTarget:self  
                                                action:@selector(handlePan:)];      
[snakeImageView addGestureRecognizer:panGestureRecognizer];  
[self.view setBackgroundColor:[UIColor whiteColor]];  
[self.view addSubview:snakeImageView];  

新建一個ImageView轿衔，然后添加手勢
回調(diào)方法：

- (void) handlePan:(UIPanGestureRecognizer*) recognizer  
{  
    CGPoint translation = [recognizer translationInView:self.view];  
    recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x,  
                                   recognizer.view.center.y + translation.y);  
    [recognizer setTranslation:CGPointZero inView:self.view];  
      
}  

4、Pinch縮放手勢

UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(handlePinch:)];

[snakeImageView addGestureRecognizer:pinchGestureRecognizer];  

回調(diào)方法

- (void) handlePinch:(UIPinchGestureRecognizer*) recognizer  
{  
    recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale);  
    recognizer.scale = 1;  
}  

5睦疫、Rotation旋轉(zhuǎn)手勢

UIRotationGestureRecognizer *rotateRecognizer = [[UIRotationGestureRecognizer alloc]  
                                                 initWithTarget:self  
                                                 action:@selector(handleRotate:)];  
[snakeImageView addGestureRecognizer:rotateRecognizer];  

回調(diào)方法：

- (void) handleRotate:(UIRotationGestureRecognizer*) recognizer  
{  
    recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation);  
    recognizer.rotation = 0;  
}  

6呀枢、添加第二個ImagView并添加手勢

記住：一個手勢只能添加到一個View笼痛，兩個View當然要有兩個手勢的實例了

- (void)viewDidLoad  
{  
    [super viewDidLoad];  
  
    UIImageView *snakeImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snake.png"]];  
    UIImageView *dragonImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"dragon.png"]];  
    snakeImageView.frame = CGRectMake(120, 120, 100, 160);  
    dragonImageView.frame = CGRectMake(50, 50, 100, 160);  
    [self.view addSubview:snakeImageView];  
    [self.view addSubview:dragonImageView];  
      
    for (UIView *view in self.view.subviews) {  
        UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc]  
                                                        initWithTarget:self  
                                                        action:@selector(handlePan:)];  
          
        UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc]  
                                                            initWithTarget:self  
                                                            action:@selector(handlePinch:)];  
          
        UIRotationGestureRecognizer *rotateRecognizer = [[UIRotationGestureRecognizer alloc]  
                                                         initWithTarget:self  
                                                         action:@selector(handleRotate:)];  
          
        [view addGestureRecognizer:panGestureRecognizer];  
        [view addGestureRecognizer:pinchGestureRecognizer];  
        [view addGestureRecognizer:rotateRecognizer];  
        [view setUserInteractionEnabled:YES];  
    }  
    [self.view setBackgroundColor:[UIColor whiteColor]];       
}  

多添加了一條龍的view裙秋，兩個view都能接收上面的三種手勢琅拌。運行效果如下：

1361954419_1036.png

7、拖動(pan手勢)速度(以較快的速度拖放后view有滑行的效果)

如何實現(xiàn)呢摘刑？
(1)監(jiān)視手勢是否結(jié)束
(2)監(jiān)視觸摸的速度

- (void) handlePan:(UIPanGestureRecognizer*) recognizer  
{  
    CGPoint translation = [recognizer translationInView:self.view];  
    recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x,  
                                       recognizer.view.center.y + translation.y);  
    [recognizer setTranslation:CGPointZero inView:self.view];  
      
    if (recognizer.state == UIGestureRecognizerStateEnded) {  
          
        CGPoint velocity = [recognizer velocityInView:self.view];  
        CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y));  
        CGFloat slideMult = magnitude / 200;  
        NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult);  
          
        float slideFactor = 0.1 * slideMult; // Increase for more of a slide  
        CGPoint finalPoint = CGPointMake(recognizer.view.center.x + (velocity.x * slideFactor),  
                                         recognizer.view.center.y + (velocity.y * slideFactor));  
        finalPoint.x = MIN(MAX(finalPoint.x, 0), self.view.bounds.size.width);  
        finalPoint.y = MIN(MAX(finalPoint.y, 0), self.view.bounds.size.height);  
          
        [UIView animateWithDuration:slideFactor*2 delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{  
            recognizer.view.center = finalPoint;  
        } completion:nil];  
          
    }  

代碼實現(xiàn)解析：

計算速度向量的長度（估計大部分都忘了）這些知識了进宝。
如果速度向量小于200，那就會得到一個小于的小數(shù)枷恕，那么滑行會很短
基于速度和速度因素計算一個終點
確保終點不會跑出父View的邊界
使用UIView動畫使view滑動到終點
運行后党晋，快速拖動圖像view放開會看到view還會在原來的方向滑行一段路。

8徐块、同時觸發(fā)兩個view的手勢

手勢之間是互斥的未玻，如果你想同時觸發(fā)蛇和龍的view，那么需要實現(xiàn)協(xié)議
UIGestureRecognizerDelegate胡控，

@interface ViewController : UIViewController<UIGestureRecognizerDelegate>  
@end  

并在協(xié)議這個方法里返回YES扳剿。

-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer  
{  
    return YES;  
}  

把self作為代理設(shè)置給手勢：

panGestureRecognizer.delegate = self;  
pinchGestureRecognizer.delegate = self;  
rotateRecognizer.delegate = self;  

這樣可以同時拖動或旋轉(zhuǎn)縮放兩個view了。

9昼激、tap點擊手勢

這里為了方便看到tap的效果庇绽，當點擊一下屏幕時，播放一個聲音橙困。
為了播放聲音瞧掺，我們加入AVFoundation.framework這個框架。

- (AVAudioPlayer *)loadWav:(NSString *)filename {  
    NSURL * url = [[NSBundle mainBundle] URLForResource:filename withExtension:@"wav"];  
    NSError * error;  
    AVAudioPlayer * player = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error];  
    if (!player) {  
        NSLog(@"Error loading %@: %@", url, error.localizedDescription);  
    } else {  
        [player prepareToPlay];  
    }  
    return player;  
}  

添加手勢的步驟和前面一樣的凡傅。

#import <UIKit/UIKit.h>  
#import <AVFoundation/AVFoundation.h>  
  
@interface ViewController : UIViewController<UIGestureRecognizerDelegate>  
@property (strong) AVAudioPlayer * chompPlayer;  
@property (strong) AVAudioPlayer * hehePlayer;  
  
@end  

- (void)handleTap:(UITapGestureRecognizer *)recognizer {  
    [self.chompPlayer play];  
}  

運行辟狈，點一下某個圖，就會播放一個咬東西的聲音夏跷。
不過這個點擊播放聲音有點缺陷哼转，就是在慢慢拖動的時候也會播放。這使得兩個手勢重合了拓春。怎么解決呢释簿？使用手勢的：requireGestureRecognizerToFail方法亚隅。

10硼莽、手勢的依賴性

在viewDidLoad的循環(huán)里添加這段代碼：

[tapRecognizer requireGestureRecognizerToFail:panGestureRecognizer];  

意思就是，當如果pan手勢失敗煮纵，就是沒發(fā)生拖動懂鸵，才會出發(fā)tap手勢。這樣如果你有輕微的拖動行疏，那就是pan手勢發(fā)生了匆光。tap的聲音就不會發(fā)出來了。

11.自定義手勢

自定義手勢繼承：UIGestureRecognizer酿联，實現(xiàn)下面的方法：

– touchesBegan:withEvent:  
– touchesMoved:withEvent:  
– touchesEnded:withEvent:  
- touchesCancelled:withEvent:  

新建一個類终息，繼承UIGestureRecognizer夺巩，代碼如下：
.h文件

#import <UIKit/UIKit.h>  
typedef enum {  
    DirectionUnknown = 0,  
    DirectionLeft,  
    DirectionRight  
} Direction;  
  
@interface HappyGestureRecognizer : UIGestureRecognizer  
@property (assign) int tickleCount;  
@property (assign) CGPoint curTickleStart;  
@property (assign) Direction lastDirection;  
  
@end  

.m文件

#import "HappyGestureRecognizer.h"  
#import <UIKit/UIGestureRecognizerSubclass.h>  
#define REQUIRED_TICKLES        2  
#define MOVE_AMT_PER_TICKLE     25  
  
@implementation HappyGestureRecognizer  
  
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {  
    UITouch * touch = [touches anyObject];  
    self.curTickleStart = [touch locationInView:self.view];  
}  
  
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {  
      
    // Make sure we've moved a minimum amount since curTickleStart  
    UITouch * touch = [touches anyObject];  
    CGPoint ticklePoint = [touch locationInView:self.view];  
    CGFloat moveAmt = ticklePoint.x - self.curTickleStart.x;  
    Direction curDirection;  
    if (moveAmt < 0) {  
        curDirection = DirectionLeft;  
    } else {  
        curDirection = DirectionRight;  
    }  
    if (ABS(moveAmt) < MOVE_AMT_PER_TICKLE) return;  
      
    // 確認方向改變了  
    if (self.lastDirection == DirectionUnknown ||  
        (self.lastDirection == DirectionLeft && curDirection == DirectionRight) ||  
        (self.lastDirection == DirectionRight && curDirection == DirectionLeft)) {  
          
        // 撓癢次數(shù)  
        self.tickleCount++;  
        self.curTickleStart = ticklePoint;  
        self.lastDirection = curDirection;  
          
        // 一旦撓癢次數(shù)超過指定數(shù)，設(shè)置手勢為結(jié)束狀態(tài)  
        // 這樣回調(diào)函數(shù)會被調(diào)用周崭。  
        if (self.state == UIGestureRecognizerStatePossible && self.tickleCount > REQUIRED_TICKLES) {  
            [self setState:UIGestureRecognizerStateEnded];  
        }  
    }  
      
}  
  
- (void)reset {  
    self.tickleCount = 0;  
    self.curTickleStart = CGPointZero;  
    self.lastDirection = DirectionUnknown;  
    if (self.state == UIGestureRecognizerStatePossible) {  
        [self setState:UIGestureRecognizerStateFailed];  
    }  
}  
  
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event  
{  
    [self reset];  
}  
  
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event  
{  
    [self reset];  
}  
  
@end  

調(diào)用自定義手勢和上面一樣柳譬，回到這樣寫：

- (void)handleHappy:(HappyGestureRecognizer *)recognizer{  
    [self.hehePlayer play];  
}  

手勢成功后播放呵呵笑的聲音。
在真機上運行续镇，按住某個view美澳，快速左右拖動，就會發(fā)出笑的聲音了摸航。
代碼解析：

先獲取起始坐標：curTickleStart
通過和ticklePoint的x值對比制跟，得出當前的放下是向左還是向右。再算出移動的x的值是否比MOVE_AMT_PER_TICKLE距離大酱虎，如果太則返回雨膨。

再判斷是否有三次是不同方向的動作，如果是則手勢結(jié)束逢净，回調(diào)哥放。