Rotate UIView to give perspective

Question

I want to change the perspective of a UIView that is in my Viewcontroller. I think that I have to transform this UIView layer, but I don't know how.

I've tried the following code but it is not working

UIView *myView = [[self subviews] objectAtIndex:0];
CALayer *layer = myView.layer;
CATransform3D rotationAndPerspectiveTransform = CATransform3DIdentity;
rotationAndPerspectiveTransform.m34 = 1.0 / -500;
rotationAndPerspectiveTransform = CATransform3DRotate(rotationAndPerspectiveTransform, 45.0f * M_PI / 180.0f, 0.0f, 1.0f, 0.0f);
layer.transform = rotationAndPerspectiveTransform;

I've also tried with the following code:

-(void)drawRect:(CGRect)rect {
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    CGAffineTransform transform = CGAffineTransformIdentity;
    transform.b = -0.1;
    transform.a = 0.9;
    CGContextConcatCTM(ctx,transform);
    // do drawing on the context
}

and this too:

CALayer *layerA = [[self.view.layer sublayers] objectAtIndex:0];


    layerA.transform = CATransform3DConcat(layerA.transform, CATransform3DMakeRotation(DEGREES_TO_RADIANS(45),1.0,0.0,0.0)

Neither of them worked. How can I change the perspective of a UIView?

In other words, I will put an example. Image this sample code, a rotation Pie RotationPie sample. I would like to change the perpective of it, in the x or z asis.

Answer 1

Your first solution works on my end. It appears like this:

Can You show your whole class code, if it doesn't work the same on your end?

EDIT

Ok, I've reconfigured provided code example, to show how it is possible:

(download here updated code example :http://www.speedyshare.com/dz469/download/Wheel-demo.zip)

And it looks like this:

I am only applying transformation to base subview. All views that are as subviews to that view, will be transformed as well. If You want corresponding subview to have different transformation - it will be harder, because, then You must take in consideration parent view transformation, to calculate new one - it can get really difficult.

But I've done some simple - multi-view level transformations. For example - to achieve effect, that view scales, moves, and rotates:

• I've applied movement transformation to parentView
• I've applied rotation transformation to parentViews first subview;
• I've applied scale transformation to parentViews first subviews subview.

EDIT

Ok, I've reconfigured provided code example, to show how it is possible, in order to leave wheel in transformed position:

(download here updated code example : http://www.speedyshare.com/5d8Xq/download/Wheel-demo2.zip )

Problem was - in this case, I was adding transformation to wheel itself - and it appears, that Wheel is based on transformations also. Therefore- when You touched it - it replaced existing transformations and applied it's own (to rotate arrows when user swipes wheel).

So - to leave it in perspective while we interact with it - we need another view layer.

I created a new View (lets call it parent view), and added wheel as a subview to this view.

Then I apply transformation to parent View instead of wheel. And it works !

I Hope it helps and You understand now more about transformations :)