iOS dragging UIImageView

Question

Ok, so I have always wondered how do I actually pick up an image view and drag it. I was planning when I drag an image view and when user places it to correct location it locks there. I really don't have idea how to do this and it has bothered me for sometime.

Thanks so much in advance!

Answer 1

Or you can use a UIPanGestureRecognizer if you don't want to subclass the view and handle touches yourself.

Create a pan recognizer in any class (e.g. view controller) and add it to your view:

UIPanGestureRecognizer * panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self
                                                                                 action:@selector(handlePanGesture:)];
[myDraggedView addGestureRecognizer:panRecognizer];

And then simply:

- (void)handlePanGesture:(UIPanGestureRecognizer *)gestureRecognizer
{
    CGRect frame = myDraggedView.frame;
    frame.origin = [gestureRecognizer locationInView:myDraggedView.superview];
    myDraggedView.frame = frame;
}

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If you like Interface Builder as much as me you can also just drag a pan gesture recognizer over your image view, and then connect the recognizer to the handlePanGesture: that should be declared as an IBAction instead of void.

Answer 2

If you're one for reading, then check out the UIResponder Class Reference, and, in particular, touchesBegan and touchesMoved.