How to rotate and resize the image view with single finger

Question

I am developing an app which has feature that resizing and rotating the imageview by dragging its bottom right corner button.

I saw one app which has feature that if

Answer 1

I had hitted the same obstacle as yours, so I developed my own modules ZDStickerView. It would be nice reference.

First of all, be sure your view's autoresizingMask should be flexible.

    autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight

otherwise resizing wouldn't work properly.

Second, I recommends you to use "CGAffineTransformMakeRotation" and "atan2" functions to solve the rotation problem, like this:

    float ang = atan2([recognizer locationInView:self.superview].y - self.center.y,
                      [recognizer locationInView:self.superview].x - self.center.x);
    float angleDiff = deltaAngle - ang;
    self.transform = CGAffineTransformMakeRotation(-angleDiff);

Third, be sure to use relative coordinate, like this:

    self.transform = CGAffineTransformMakeRotation(-angleDiff);