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IOS學習之 手勢操作

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1. UIGestureRecognizer介紹 UIGestureRecognizer類是個抽象類,下面的子類是具體的手勢,開發這可以直接使用這些手勢識別。     UITapGestureRecognizer                // 點擊     UIPinchGestureRecognizer            // 二指往內或往外撥動,平時經常用到的縮放     UIRotationGestureRecognizer       // 旋轉     UISwipeGestureRecognizer           // 滑動,快速移動     UIPanGestureRecognizer               // 拖移,慢速移動     UILongPressGestureRecognizer   // 長按   2、使用手勢的步驟 使用手勢很簡單,分為兩步: (1)創建手勢實例。當創建手勢時,指定一個回調方法,當手勢開始,改變、或結束時,回調方法被調用。 (2)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,那就會回調方法。 ps:一個手勢只能對應一個View,但是一個View可以有多個手勢。   3、Pan 拖動手勢:  
// 新建一個ImageView,然後添加手勢
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];

// 回調方法:
- (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:)];
                                                         
- (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;  
}

 

    6、添加第二個ImagView並添加手勢 記住:一個手勢只能添加到一個View,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]];       
}

 

    7、拖動(pan手勢)速度(以較快的速度拖放後view有滑行的效果) 如何實現呢?     1.監視手勢是否結束     2.監視觸摸的速度  
- (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];  
    }

 

  代碼實現解析:     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 運行後,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、同時觸發兩個view的手勢 手勢之間是互斥的,如果你想同時觸發蛇和龍的view,那麼需要實現協議UIGestureRecognizerDelegate, 並在協議這個方法裡返回YES。  
-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {  
    return YES;  
}

 

  把self作為代理設置給手勢:  
panGestureRecognizer.delegate = self;  
pinchGestureRecognizer.delegate = self;  
rotateRecognizer.delegate = self;

 

  這樣可以同時拖動或旋轉縮放兩個view了。 1 9、tap點擊手勢 這裡為了方便看到tap的效果,當點擊一下屏幕時,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;  
}

 

  我會在最後例子代碼給出完整代碼,添加手勢的步驟和前面一樣的。  
#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,點一下某個圖,就會播放一個咬東西的聲音。 不過這個點擊播放聲音有點缺陷,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的循環裡添加這段代碼: 1 [tapRecognizer requireGestureRecognizerToFail:panGestureRecognizer]; 意思就是,當如果pan手勢失敗,就是沒發生拖動,才會出發tap手勢。這樣如果你有輕微的拖動,那就是pan手勢發生了。tap的聲音就不會發出來了。   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,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  
        self.tickleCount++;  
        self.curTickleStart = ticklePoint;  
        self.lastDirection = curDirection;  
  
        // 一旦撓癢次數超過指定數,設置手勢為結束狀態  
        // 這樣回調函數會被調用。  
        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

 

  調用自定義手勢和上面一樣,回到這樣寫:  
- (void)handleHappy:(HappyGestureRecognizer *)recognizer{  
    [self.hehePlayer play];  
}

 

  手勢成功後播放呵呵笑的聲音。 在真機上運行,按住某個view,快速左右拖動,就會發出笑的聲音了。 代碼解析: 先獲取起始坐標:curTickleStart 通過和ticklePoint的x值對比,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,如果太則返回。 再判斷是否有三次是不同方向的動作,如果是則手勢結束,回調。
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