Keep size/position of CALayer on UIView when rotated

Question

I have an UIImage with the following properties:

imageView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth; 
imageView.contentMode = UIViewContentModeScaleAspectFit;

Later on I add a custom CALayer to the imageview at a given position.

When I rotate my imageview the image is scaled to fit (given the contentMode), but now my CALayer is positioned wrong. Apparently only the Y-position is wrong. How can I make my CALayer reposition correctly when view is rotated?

Answer 1

As far as i know, in order to position/layout your custom layer, you should subclass your imageview and implement this method:

- (void) layoutSublayersOfLayer:(CALayer*)layer
{
    [super layoutSublayersOfLayer:layer];

    self.customlayer.position = CGPointMake(
            self.bounds.size.width / 2, self.bounds.size.height / 2);
}

If you don't want to subclass imageview, you can try this way. This code should be in your imageview-controller:

- (void) viewDidLoad
{
    [super viewDidLoad];

    self.container = [CALayer layer];
    self.container.bounds = self.imageview.bounds;
    self.container.delegate = self;

    [self.container addSublayer:self.customlayer];
    [self.imageview.layer addSublayer:self.container];
}

- (void) layoutSublayersOfLayer:(CALayer*)layer    // this is layers delegate method
{
    if (layer == self.container)
    {
        self.customlayer.position = CGPointMake(self.container.bounds.size.width / 2, 
                                                self.container.bounds.size.height / 2);
    }
}