ioscatransformlayer

Autolayout and CGAffineTransform

I am trying to scale a UIView during user interaction and I implemented the CGAffineTransform on the view as follows:

@implementation Tileview
{
CGAffineTransform _tempTransform;
}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
 {
_tempTransform = self.transform;
self.transform = CGAffineTransformScale(self.transform, 1.2, 1.2);
}

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
 {
self.transform = _tempTransform;
}

This seemed to scale the view well but I noticed later that I started to have unpredictable results when moving views around on the screen, and doing some research I learned that this is possibly because I am using autolayout. The recommendation was to animate the layer rather than the view object.

So I attempted to refactor the above code to use CATranform3D becauseit seemed that the CAAffineTransform could not be applied to the layer. But a CATransform3D could be. But I haven't been able to figure out how to make the layer scale using that Transform object.

I have attempted to apply a transform to the View's layer as follows: 

self.layer.sublayerTransform = CATransform3DMakeScale(1.2, 1.2, 0.0f);

And that scales all the sublayers of my view

But I try to apply that to

 self.layer = CATransform3DMakeScale(1.2, 1.2, 0.0f);

I get an error saying

Assignment to readonly property

I also looked at the CATransformLayer class, but when try to assign that to self.layer I get an error saying:

Assignment to CATransformLayer from incompatible type CATransform3D

So my question is, is there a way to scale the UIView's layer without interfering with the Autolayout coordinants.

Solution

  • Why are you using sublayer transform? This should work:

    self.layer.transform = CATransform3DScale(self.layer.transform, 1.2, 1.2, 1);

    And also you can apply affine transforms to a layer if you really need to via CATransform3DMakeAffineTransform(<#CGAffineTransform m#>)

    I've noticed that you are saving the initial transform to apply it after touches has ended. You can restore initial transform simply by 

    self.layer.transform = CATransform3DIdentity;