iOS之UIGestureRecognizer_手勢識別的簡單用法

UIGestureRecognizer基類是一個抽象類，我們主要是使用它的子類

列舉一下我常用的幾種手勢識別

UIPanGestureRecognizer拖拽手勢

UIPinchGestureRecognizer捏合縮放手勢

UIRotationGestureRecognizer旋轉手勢

UITapGestureRecognizer點擊手勢

UILongPressGestureRecognizer長按手勢

我用工程代碼簡單的說一下這幾種手勢識別器的用法

在ViewDidLoad中寫一個ImageView,並給它加手勢識別

@interface ViewController ()<UIGestureRecognizerDelegate>

掛上代理

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    
    UIImageView *imageView = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, 200, 200)];
    imageView.center = self.view.center;
    imageView.userInteractionEnabled = YES;
    [imageView setImage:[UIImage imageNamed:@"1.png"]];
    [self.view addSubview:imageView];

}

如果你想要多個手勢同時起作用，記得實現這個方法

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

第一種手勢

1.Pan拖拽手勢

UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(panImageView:)];
    [imageView addGestureRecognizer:panGesture];

實現拖拽的方法

#pragma mark--拖拽
- (void)panImageView:(UIPanGestureRecognizer *)pan
{

    CGPoint point = [pan translationInView:self.view];
    pan.view.center = CGPointMake(pan.view.center.x+point.x, pan.view.center.y+point.y);
    [pan setTranslation:CGPointZero inView:self.view];
    
    
}

效果就是圖片可以隨意拖動，手勢停止圖片馬上停止在拖動最後停止的位置，如果覺得動作太生硬，可以添加一下代碼，使圖片在拖動停止後滑動一小段距離

/*

 代碼實現解析：

 計算速度向量的長度。

 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

 基於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

 */

#pragma mark--拖拽
- (void)panImageView:(UIPanGestureRecognizer *)pan
{

    CGPoint point = [pan translationInView:self.view];
    pan.view.center = CGPointMake(pan.view.center.x+point.x, pan.view.center.y+point.y);
    [pan setTranslation:CGPointZero inView:self.view];
    
    //想要拖動後有滑行的效果
    if (pan.state == UIGestureRecognizerStateEnded) {
        
        CGPoint velocity = [pan velocityInView:self.view];
        CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y));
        CGFloat slideMult = magnitude / 200;
        
        float slideFactor = 0.1 * slideMult; // Increase for more of a slide
        CGPoint finalPoint = CGPointMake(pan.view.center.x + (velocity.x * slideFactor),
                                         pan.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:^{
            pan.view.center = finalPoint;
        } completion:nil];
        
    }
}

第二種手勢

Pinch捏合縮放手勢

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

實現捏合手勢方法

#pragma mark--捏合
- (void)pinchView:(UIPinchGestureRecognizer *)pinch
{
    pinch.view.transform = CGAffineTransformScale(pinch.view.transform, pinch.scale, pinch.scale);
    pinch.scale = 1; // scale表示縮放比例
    
}

第三種手勢

Rotation旋轉手勢

UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc]initWithTarget:self action:@selector(rotationImageView:)];
    [imageView addGestureRecognizer:rotation];

旋轉手勢實現方法

#pragma mark--旋轉
- (void)rotationImageView:(UIRotationGestureRecognizer *)rotation
{

    rotation.view.transform = CGAffineTransformRotate(rotation.view.transform, rotation.rotation);
    rotation.rotation = 0;
}

第四種手勢

Tap單擊手勢

UITapGestureRecognizer *SingleTapGesture = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tapImageView:)];
    [imageView addGestureRecognizer:SingleTapGesture];

Tap雙擊手勢

UITapGestureRecognizer *DoubleTapGesture = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tapImageView:)];
    <span style="color:#cc33cc;">DoubleTapGesture.numberOfTapsRequired = 2;</span>
    [imageView addGestureRecognizer:DoubleTapGesture];

點擊手勢實現方法，這裏爲了區別單擊和雙擊效果，我在點擊的時候有文本提示

#pragma mark--點擊
- (void)tapImageView:(UITapGestureRecognizer *)tap
{
    UILabel *lable = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, 50, 30)];
    [lable setFont:[UIFont systemFontOfSize:14]];
    
    if (tap.numberOfTapsRequired == 1) {
        [lable setText:@"單擊"];
    }else{
    
        [lable setText:@"雙擊"];
    }
    
    CGPoint point = [tap locationInView:self.view];
    lable.center = point;
    [self.view addSubview:lable];
    [self performSelector:@selector(hideLable) withObject:self afterDelay:1];
  
}

在此處順便提一下手勢之間的依賴關係，比如說我現在有了單擊手勢了，我又想要雙擊手機，當我雙擊的時候也會相應單擊手勢的方法，這樣就不好了，所有有了這個[A requireGestureRecognizerToFail：B]函數，它可以指定當A手勢發生時，即便A已經滿足條件了，也不會立刻觸發，會等到指定的手勢B確定失敗之後才觸發。

所以可以這樣寫

[SingleTapGesturerequireGestureRecognizerToFail:DoubleTapGesture];

第五種手勢

Long長按手勢

UILongPressGestureRecognizer *LongGesture = [[UILongPressGestureRecognizer alloc]initWithTarget:self action:@selector(LongGesture:)];
    [imageView addGestureRecognizer:LongGesture];

長按手勢的實現方法

#pragma mark--長按
- (void)LongGesture:(UILongPressGestureRecognizer *)longGesture
{

    if (longGesture.state == UIGestureRecognizerStateBegan) {
        UILabel *lable = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, 70, 30)];
        [lable setFont:[UIFont systemFontOfSize:14]];
        [lable setText:@"長按手勢啦"];
        
        CGPoint point = [longGesture locationInView:self.view];
        lable.center = point;
        [self.view addSubview:lable];
        [self performSelector:@selector(hideLable) withObject:self afterDelay:1];
    }
    
}

運行的效果：