iOS手勢識別的詳細使用(拖動,縮放,旋轉,點選,手勢依賴,自定義手勢)

• UITapGestureRecognizer  
• UIPinchGestureRecognizer
• UIRotationGestureRecognizer
• UISwipeGestureRecognizer
• UIPanGestureRecognizer
• UILongPressGestureRecognizer

• Tap（點一下）
• Pinch（二指往內或往外撥動，平時經常用到的縮放）
• Rotation（旋轉）
• Swipe（滑動，快速移動）
• Pan （拖移，慢速移動）
•  LongPress（長按）

1. 建立手勢例項。當建立手勢時，指定一個回撥方法，當手勢開始，改變、或結束時，回撥方法被呼叫。
2. 新增到需要識別的View中。每個手勢只對應一個View，當螢幕觸控在View的邊界內時，如果手勢和預定的一樣，那就會回撥方法。

    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];

- (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];

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

5、Rotation旋轉手勢

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

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

- (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]];     
}

1. 監視手勢是否結束
2. 監視觸控的速度

- (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];
        
    }
   

1. 計算速度向量的長度（估計大部分都忘了）這些知識了。
2. 如果速度向量小於200，那就會得到一個小於的小數，那麼滑行會很短
3. 基於速度和速度因素計算一個終點
4. 確保終點不會跑出父View的邊界
5. 使用UIView動畫使view滑動到終點

UIGestureRecognizerDelegate，

@interface ViewController : UIViewController<UIGestureRecognizerDelegate>
@end

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

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

9、tap點選手勢

這裡為了方便看到tap的效果，當點選一下螢幕時，播放一個聲音。

為了播放聲音，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;
}

#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];
}

執行，點一下某個圖，就會播放一個咬東西的聲音。

不過這個點選播放聲音有點缺陷，就是在慢慢拖動的時候也會播放。這使得兩個手勢重合了。怎麼解決呢？使用手勢的：requireGestureRecognizerToFail方法。

10、手勢的依賴性

在viewDidLoad的迴圈裡新增這段程式碼：

        [tapRecognizer requireGestureRecognizerToFail:panGestureRecognizer];

11、自定義手勢

自定義手勢繼承：UIGestureRecognizer，實現下面的方法：

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

新建一個類，繼承UIGestureRecognizer，程式碼如下：

.h檔案

#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

#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
        self.tickleCount++;
        self.curTickleStart = ticklePoint;
        self.lastDirection = curDirection;
        
        // 一旦撓癢次數超過指定數，設定手勢為結束狀態
        // 這樣回撥函式會被呼叫。
        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

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

容芳志 (http://blog.csdn.net/totogo2010)

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