iosuipangesturerecognizer

ios UIPanGestureRecognizer pointer position

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

- (void)pan:(UIPanGestureRecognizer *)gesture {
    NSLog(@"%f", [gesture translationInView:self].x);
}

The above code will log the relative position of my current pan, but how can I get the absolute position for the view I'm in?

I'm simply just wanting to slide a UIImageView to wherever the user's finger is.

Solution

  • translationInView gives you the pan translation (how much x has changed) and not the position of the pan in the view (the value of x). If you need the position of the pan, you have to use the method locationInView.

    You can find the coordinates relatively to the view as follows:

    - (void)pan:(UIPanGestureRecognizer *)gesture {
    NSLog(@"%f", [gesture locationInView:self].x);
}

    Or relatively to the superview:

    - (void)pan:(UIPanGestureRecognizer *)gesture {
    NSLog(@"%f", [gesture locationInView:self.superview].x);
}

    Or relatively to the window:

    - (void)pan:(UIPanGestureRecognizer *)gesture {
    NSLog(@"%f", [gesture locationInView:self.window].x);
}