Set Layer Content to UIImage inside a CALayer subclass - not working - iphone

Question

I'm trying to display a UIImage selected from a UIImagePickerController inside a subclass of CALayer and add it to my superview but I can't get it to work.
This is how I Get the Image from the UIImagePickerController, which seems to work good :
- (IBAction)importImage:(id)sender
{
UIImagePickerController *imagePickerController = [[UIImagePickerController alloc] init];
imagePickerController.delegate = self;
imagePickerController.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
UIPopoverController *popover = [[UIPopoverController alloc] initWithContentViewController:imagePickerController];
[popover setPopoverContentSize:CGSizeMake(320,320)];
[popover presentPopoverFromRect:importBackgroundButton.frame inView:self.view permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
self.popoverController = popover;
[imagePickerController release];
}
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
[self.popoverController dismissPopoverAnimated:YES];
UIImage* img = [info objectForKey:UIImagePickerControllerOriginalImage];
[[context currentDrawing] setBkgImage:img];
}
This is my subclass of CALayer which contains the UIImage to display :
#interface UI_BackgroundImageLayer : CALayer
{
//This is for the Import image as background feature
UIImage* _bkgImg;
}
#property (nonatomic, retain) UIImage* _bkgImg;
-(void)update:(UIImage*)src;
#end
////
#implementation UI_BackgroundImageLayer
- (id)init
{
self = [ super init ];
// [self resetTransform ];
_bkgImg = nil;
return self;
}
-(void)update:(UIImage*)src
{
_bkgImg = [[UIImage alloc] initWithCGImage:src.CGImage];
self.contentsGravity = kCAGravityResizeAspect;
self.contents = (id)_bkgImg.CGImage;
}
#end
I update the content of the CALayer when the user select another image !
The CALayer is added to the superview from start like this :
[[_superView layer] insertSublayer:context._imgLayer atIndex:0];
It's inserted at index 0 because it's meant to be a background image so it must be under other UI elements and drawings.
All of this seems good to me, but nothing appears on the screen ...

Answer 1

Are you using XCode v4.2? If so, this may be relevant to you or it may not but it's worth a look. I've had exacty the same problem as you with CALayer subclasses not responding to the usual display methods (like setCornerRadius, setBackgroundColor etc...). Try this; in your hosting view, just after you've instanced the VIEW put the following line;
[self setBackgroundColor [UIColor clearColor]];
You may well find that from that point on, your layer subclass works perfectly.
My view subclass code looks like this;
// layerClass
+ (Class) layerClass {
return [myLayerSubclass class];
}
// View subclass init routine
- (id) initWithFrame: (CGRect) p_frame {
self = [super initWithFrame: p_frame];
if (self) {
[self setBackgroundColor: [UIColor clearColor]]; // *** BUG WORKARUND? *** Note: Do Apple know about this?
// Rest of your view init ....
}
return self;
}
It seems that the layer subclass does not respond until its hosting view has 'acknowledged' that it's there. It took me days to debug but now all my code works perfectly.
Hope this helps.
V.V.