ios - Pinch/zoom from current scale

gesture-recognition, ios, uigesturerecognizer, uiview

Solution

In .h file, add:

CGFloat _lastScale;

In .m file,

- (id)init  {
    ...
    _lastScale = 1.0f;
    ...
}

- (void)twoFingerPinch:(UIPinchGestureRecognizer *)recognizer 
{
    if (recognizer.state == UIGestureRecognizerStateEnded)  {
        _lastScale = 1.0f;
        return;
    }

    CGFloat scale = 1.0f - (_lastScale - recognizer.scale);
    CGAffineTransform tr = CGAffineTransformScale(self.view.transform, scale, scale);
    self.container.transform = tr;

    _lastScale = recognizer.scale;
}

Problem

The following code correctly pinches/zooms the container view, but only after it jumps to a scale of 1.0. How can I modify it so that the container view scales from it's current scale? ``` UIPinchGestureRecognizer *twoFingerPinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(twoFingerPinch:)]; [self.container addGestureRecognizer:twoFingerPinch]; - (void)twoFingerPinch:(UIPinchGestureRecognizer *)recognizer { _scale = recognizer.scale; CGAffineTransform tr = CGAffineTransformScale(self.view.transform, _scale, _scale); self.container.transform = tr; } ```

Original source