如何使用UIPanGestureRecognizer移动对象？iPhone/iPad

Question

UIPanGestureRecognizer 类有几个示例。例如，我已经阅读了 this，但仍无法使用它...

在我正在工作的 nib 文件中，我有一个 UIView（图像上的白色矩形），我希望使用该类来拖动它：

而在我的.m文件中，我已经放置了：

- (void)setTranslation:(CGPoint)translation inView:(UIView *)view
{
    NSLog(@"Test to see if this method gets executed");
}

并且当我拖动鼠标穿过 UIView 时，该方法不会被执行。我也尝试过放置：

- (void)pan:(UIPanGestureRecognizer *)gesture
{
    NSLog(@"testing");
}

那个方法也没有被执行。也许我错了，但我认为这些方法应该像- (void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event方法一样工作，我只需要放置该方法，每当有触摸时它就会被调用。

我做错了什么？也许我必须连接到那个方法吗？如果是这样，我该怎么做？

- Tono Nam

Answer 1

我找到了教程“使用UIGestureRecognizers”，我认为那正是我需要的。这帮助我得出了以下解决方案：

-(IBAction) someMethod {
    UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(move:)];
    [panRecognizer setMinimumNumberOfTouches:1];
    [panRecognizer setMaximumNumberOfTouches:1];
    [ViewMain addGestureRecognizer:panRecognizer];
    [panRecognizer release];
}

-(void)move:(UIPanGestureRecognizer*)sender {
    [self.view bringSubviewToFront:sender.view];
    CGPoint translatedPoint = [sender translationInView:sender.view.superview];

    if (sender.state == UIGestureRecognizerStateBegan) {
        firstX = sender.view.center.x;
        firstY = sender.view.center.y;
    }


    translatedPoint = CGPointMake(sender.view.center.x+translatedPoint.x, sender.view.center.y+translatedPoint.y);

    [sender.view setCenter:translatedPoint];
    [sender setTranslation:CGPointZero inView:sender.view];

    if (sender.state == UIGestureRecognizerStateEnded) {
        CGFloat velocityX = (0.2*[sender velocityInView:self.view].x);
        CGFloat velocityY = (0.2*[sender velocityInView:self.view].y);

        CGFloat finalX = translatedPoint.x + velocityX;
        CGFloat finalY = translatedPoint.y + velocityY;// translatedPoint.y + (.35*[(UIPanGestureRecognizer*)sender velocityInView:self.view].y);

        if (finalX < 0) {
            finalX = 0;
        } else if (finalX > self.view.frame.size.width) {
            finalX = self.view.frame.size.width;
        }

        if (finalY < 50) { // to avoid status bar
            finalY = 50;
        } else if (finalY > self.view.frame.size.height) {
            finalY = self.view.frame.size.height;
        }

        CGFloat animationDuration = (ABS(velocityX)*.0002)+.2;

        NSLog(@"the duration is: %f", animationDuration);

        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDuration:animationDuration];
        [UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
        [UIView setAnimationDelegate:self];
        [UIView setAnimationDidStopSelector:@selector(animationDidFinish)];
        [[sender view] setCenter:CGPointMake(finalX, finalY)];
        [UIView commitAnimations];
    }
}

- Tono Nam

---

太棒了！！我喜欢animationDuration的计算，效果很棒。 - 最白目

如果你将move:(id)sender更改为move:(UIPanGestureRecognizer*)sender，就不必进行所有那些丑陋的类型转换。 - Wex

这个解决方案对UISwitch不起作用。我还尝试了实现touchesBegan、touchesMoved方法，但无法移动UISwitch。请问你能告诉我如何通过拖动来移动UISwitch吗？ - DShah

请记得将与手势识别器相关联的视图的userInteractionEnabled属性设置为YES。 - Lukas Kalinski

firstX和firstY是什么？ - Krekin

Answer 2

UIPanGestureRecognizer * pan1 = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(moveObject:)];
pan1.minimumNumberOfTouches = 1;
[image1 addGestureRecognizer:pan1];

-(void)moveObject:(UIPanGestureRecognizer *)pan;
{
 image1.center = [pan locationInView:image1.superview];
}

- Arun Kulasegaran

---

无懈可击的胜利！ - manuelBetancurt

无法否认这种简单性，但是这个解决方案存在一个问题：一旦你放下手指开始手势，image1 就会跳动，可能会跳得很远，以至于它的中心在你的手指下面。最好通过 pan 的平移来调整 image1.center，以获得更流畅和标准的体验。 - sartak

Answer 3

-(IBAction)Method
{
      UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)];
      [panRecognizer setMinimumNumberOfTouches:1];
      [panRecognizer setMaximumNumberOfTouches:1];
      [ViewMain addGestureRecognizer:panRecognizer];
      [panRecognizer release];
}
- (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:CGPointMake(0, 0) 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];

    }

}

- Mohit

---

你可以将 CGPointMake(0, 0) 替换为 CGRectZero。 - meaning-matters

你的意思是 CGPointZero 吗？ - mylogon

@mylogon 你说得对。作为感谢，我会赞同你的一些答案。 - meaning-matters

Answer 4

@Tono Nam在Swift 5中的答案（被接受）

func someMethod() {
    let panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(move))
    panGestureRecognizer.minimumNumberOfTouches = 1
    panGestureRecognizer.maximumNumberOfTouches = 1
    view.addGestureRecognizer(panGestureRecognizer)
}

@objc func move(sender: UIPanGestureRecognizer) {
    guard let senderView = sender.view else { return }
    
    self.view.bringSubviewToFront(senderView)
    var translatedPoint: CGPoint = sender.translation(in: senderView.superview)
    
    if(sender.state == .began) {
        let firstX = senderView.center.x
        let firstY = senderView.center.y
    }
    
    translatedPoint = CGPoint(x: senderView.center.x + translatedPoint.x, y: senderView.center.y + translatedPoint.y)
    senderView.center = translatedPoint
    sender.setTranslation(.zero, in: senderView)
    
    if(sender.state == .ended) {
        let velocityX: CGFloat = (0.2 * sender.velocity(in: self.view).x)
        let velocityY: CGFloat = (0.2 * sender.velocity(in: self.view).y)
        
        var finalX: CGFloat = translatedPoint.x + velocityX
        var finalY: CGFloat = translatedPoint.y + velocityY
        
        if(finalX < 0) {
            finalX = 0
        } else if (finalX > self.view.frame.size.width) {
            finalX = self.view.frame.size.width;
        }
        
        if (finalY < 50) { // to avoid status bar
            finalY = 50;
        } else if (finalY > self.view.frame.size.height) {
            finalY = self.view.frame.size.height;
        }
        
        let animationDuration: TimeInterval = TimeInterval(abs(velocityX) * 0.0002 + 0.2)
        print("the animation duration is \(animationDuration)")
        
        UIView.animate(withDuration: animationDuration, delay: 0, options: .curveEaseOut) {
            senderView.center = CGPoint(x: finalX, y: finalY)
        } completion: { completed in
            // call animationDidFinish completion handler here
        }
    }
}

- Victor

Answer 5

几年后，我开始涉足编程领域。

需要保存图像视图的起始中心：

var panBegin: CGPoint.zero

然后使用变换更新新的中心：

if recognizer.state == .began {
     panBegin = imageView!.center

} else if recognizer.state == .ended {
    panBegin = CGPoint.zero

} else if recognizer.state == .changed {
    let translation = recognizer.translation(in: view)
    let panOffsetTransform = CGAffineTransform( translationX: translation.x, y: translation.y)

    imageView!.center = panBegin.applying(panOffsetTransform)
}

- atreat

Answer 6

if ([recognizer state] == UIGestureRecognizerStateChanged)    
{
    CGPoint translation1 = [recognizer translationInView:main_view];
    img12.center=CGPointMake(img12.center.x+translation1.x, img12.center.y+ translation1.y);
    [recognizer setTranslation:CGPointMake(0, 0) inView:main_view];

    recognizer.view.center=CGPointMake(recognizer.view.center.x+translation1.x, recognizer.view.center.y+ translation1.y);
}

-(void)move:(UIPanGestureRecognizer*)recognizer
{
    if ([recognizer state] == UIGestureRecognizerStateChanged)    
    {
        CGPoint translation = [recognizer translationInView:self.view];
        recognizer.view.center=CGPointMake(recognizer.view.center.x+translation.x, recognizer.view.center.y+ translation.y);
        [recognizer setTranslation:CGPointMake(0, 0) inView:self.view];
    }
}

- P.J.Radadiya

Answer 7

这是@MS AppTech答案的Swift 2版本

func handlePan(panGest : UIPanGestureRecognizer) {
let velocity : CGPoint = panGest.velocityInView(self.view);
        let magnitude : CGFloat = CGFloat(sqrtf((Float(velocity.x) * Float(velocity.x)) + (Float(velocity.y) * Float(velocity.y))));
        let slideMult :CGFloat = magnitude / 200;
        //NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult);

        let slideFactor : CGFloat = 0.1 * slideMult; // Increase for more of a slide
        var finalPoint : CGPoint = CGPointMake(panGest.view!.center.x + (velocity.x * slideFactor),
                                         panGest.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(Double(slideFactor*2), delay: 0, options: UIViewAnimationOptions.CurveEaseOut, animations: {
            panGest.view!.center = finalPoint;
            }, completion: nil)
}

- hamidrezabstn

Answer 8

作为补充，因为我花了很多时间在这上面：我的视图（我在上面应用了addGestureRecognizer）是动态创建的，所以我确实需要将userInteractionEnabled修复为true。

- tontonCD

Answer 9

Swift 2版本：

// start detecting pan gesture
let panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(TTAltimeterDetailViewController.panGestureDetected(_:)))
panGestureRecognizer.minimumNumberOfTouches = 1
self.chartOverlayView.addGestureRecognizer(panGestureRecognizer)

func panGestureDetected(panGestureRecognizer: UIPanGestureRecognizer) {
    print("pan gesture recognized")
}

- richdcs