Home/ Questions/Q 6064043
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-23T09:14:13+00:00

I have a custom UIImageView, I can drag it around screen by making a

  • 0

I have a custom UIImageView, I can drag it around screen by making a translation with (xDif and yDif is the amount fingers moved):

CGAffineTransform translate = CGAffineTransformMakeTranslation(xDif, yDif);
[self setTransform: CGAffineTransformConcat([self transform], translate)];

Let’s say I moved the ImageView for 50px in both x and y directions. I then try to rotate the ImageView (via gesture recognizer) with:

CGAffineTransform transform = CGAffineTransformMakeRotation([recognizer rotation]);
myImageView.transform = transform;

What happens is the ImageView suddenly moves to where the ImageView was originally located (before the translation – not from the moved position + 50px in both directions).

(It seems that no matter how I translate the view, the self.center of the ImageView subclass stays the same – where it was originally laid in IB).

Another problem is, if I rotate the ImageView by 30 deg, and then try to rotate it a bit more, it will again start from the original position (angle = 0) and go from there, why wouldn’t it start from the angle 30 deg and not 0.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    You are overwriting the earlier transform. To add to the current transform, you should do this –

    myImageView.transform = CGAffineTransformRotate(myImageView.transform, recognizer.rotation);

    Since you’re changing the transform property in a serial order, you should use CGAffineTransformRotate, CGAffineTransformTranslate and CGAffineTransformScale instead so that you add to the original transform and not create a new one.

    • 0