How to use Pan Gestures

Question

Im a beginner programmer with Xcode 5 and was attempting to write code to allow a user to move a image with input from the users touch.

So far, I believe that my code is correct but i believe I'm missing something as the UIImage refuses move. Although when attempt to test it with NSLog I don't get a response which shows it working. My guess it that I have to make a custom class for the image and if so would I do this and how would I link it.

For example

  @implementation StartPage
  - (IBAction)HandlePan:(UIGestureRecognizer *)sender; {
  NSLog(@"panning"); //Testing to check if the image moves when touched by user.

  CGPoint NetTranslation ;
  CGPoint Translation =
 [(UIPanGestureRecognizer *) sender translationInView: _Imageview ];

  sender.view.transform=CGAffineTransformMakeTranslation (

  NetTranslation.x += Translation.x,
  NetTranslation.y += Translation.y);
  enter code here
  if(sender.state == UIGestureRecognizerStateEnded)
  {
   NetTranslation.x += Translation.x;
   NetTranslation.y += Translation.y;
  }

}

Answer 1

If your HandlePan method is not called check that your _Imageview has user interactions enabled:

_Imageview.userInteractionEnabled = YES

Answer 2

While using any Gesture you should use following steps,

Now you are using pan gesture so i am giving following steps to add pan gesture,

1. Add delegate like to your header file [ .h file ]

   @interface ViewName : UIView <UIGestureRecognizerDelegate>
   

2. Declare that gesture

   @property (nonatomic,strong) UIPanGestureRecognizer *pan;
   

3. Allocate that gesture

   pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(handlePan:)];
   

4. Mention where these delegate methods are present

   pan.delegate = self;
   

5. Adding that gesture to the view like

   [self.view addGestureRecognizer:pan];
   

6. Defining the handlePan method like as

   - (void)handlePan:(UIPanGestureRecognizer *)recognizer
   { 
      // code for pan gesture here
   }
   

I think you missed to do something... Hope this will solve your problem, check whether you added UIGestureRecognizer in header file or not...

Answer 3

For swift language we can do like this:

Take a view and set IBOutlet:

@IBOutlet weak var viewDrag: UIView!

var panGesture = UIPanGestureRecognizer()

Write this pretty code on viewDidLoad()

 panGesture = UIPanGestureRecognizer(target: self, action: #selector(self.draggedView(_:)))
    viewDrag.isUserInteractionEnabled = true
    viewDrag.addGestureRecognizer(panGesture)

This is method which is calling while gesture recognized

 @objc func draggedView(_ sender:UIPanGestureRecognizer){
    self.view.bringSubviewToFront(viewDrag)
    let translation = sender.translation(in: self.view)
    viewDrag.center = CGPoint(x: viewDrag.center.x + translation.x, y: viewDrag.center.y + translation.y)
    sender.setTranslation(CGPoint.zero, in: self.view)
}

100% working and tested