86

There are several examples of the UIPanGestureRecognizer class. For example I have read this and I am still not able to use it...

On the nib file that I am working on I have a UIView (white rectangle on image) that I wish to drag with that class:

enter image description here

and in my .m file I have placed:

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

and that method does not get executed when I drag the mouse across the UIView. I have also tried placing:

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

And that method does not get executed either. Maybe I am wrong but I think this methods should work like the - (void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event method where I just have to place that method and it will get called whenever there are touches.

What am I doing wrong? Maybe do I have to draw a connection to that method? If so how can I do that?

KlimczakM
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Tono Nam
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9 Answers9

149

I found the tutorial Working with UIGestureRecognizers, and I think that is what I am looking for. It helped me come up with the following solution:

-(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];
    }
}
Mostafa Sultan
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Tono Nam
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    If you change move:(id)sender to be move:(UIPanGestureRecognizer*)sender you don't have to do all that ugly typecasting. – Wex Jun 14 '13 at 09:56
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    This solution is not working for UISwitch. Also I tried implementing touchesBegan, touchesMoved methods but not able to move UISwitch. Can you please tell me how can I move UISwitch just by Dragging?? – DShah Dec 02 '13 at 17:59
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    Remember to have userInteractionEnabled=YES for the view with which the gesture recognizer is associated. – Lukas Kalinski May 19 '15 at 00:31
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    What are firstX and firstY? – Krekin Dec 28 '15 at 11:51
  • Just in case someone is wondering like Krekin, firstX and firstY are the x and y of the CGPoint. Assign it to your moveableView's, like so ```[_moveableView setCenter:CGPointMake(x, y)];``` – Glenn Posadas Jul 28 '18 at 15:38
40
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];
}
Paras Joshi
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Arun Kulasegaran
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  • flawless victory! – manuelBetancurt Feb 28 '17 at 00:40
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    Can't argue with the simplicity, but this solution has a problem: as soon as you put your finger down to start the gesture, `image1` will jump, potentially quite far, so that its center is under your finger. Better to adjust `image1.center` by the `pan`'s translation for a more fluid and standard experience. – sartak Mar 03 '18 at 20:10
26
-(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];

    }

}
jbrennan
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Mohit
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2

@Tono Nam's answer (accepted) in Swift 5

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
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1
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
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1

swift 2 version of the @MS AppTech answer

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
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1

Casting my hat into the ring a couple years later.

Will need to save the beginning center of the image view:

var panBegin: CGPoint.zero

Then update the new center using a transform:

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
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0

As an addition, because I spend a lot of time on this: my view (which I applied addGestureRecognizer on) was dynamically created, so I did have to fix userInteractionEnabled to true

tontonCD
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-2

The Swift 2 version:

// 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")
}
Dovydas Šopa
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richdcs
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