苹果手机。将PNG加载到CGLayer不起作用

我有一个CGLayer是这样创建的:

CGSize size = CGSizeMake(500, 500);

UIGraphicsBeginImageContext(tamanho);
ctx = UIGraphicsGetCurrentContext();
[self loadImageToCTX]; // this method loads an image into CTX

lineLayer = CGLayerCreateWithContext (ctx, size, NULL);

现在我有一个PNG,有alpha和一些内容。我需要把这个PNG加载到lineLayer,所以我。。。

// lineLayer is empty, lets load a PNG into it
CGRect superRect = CGRectMake(0,0, 500, 500);

CGContextRef lineContext = CGLayerGetContext (lineLayer);
CGContextSaveGState(lineContext);

// inverting Y, so image will not be loaded flipped 
CGContextTranslateCTM(lineContext, 0, -500);
CGContextScaleCTM(lineContext, 1.0, -1.0);

//  CGContextClearRect(lineContext, superRect);

UIImage *loaded = [self recuperarImage:@"LineLayer.png"];
CGContextDrawImage(lineContext, superRect, loaded.CGImage);
CGContextRestoreGState(lineContext);

如果我现在渲染ctx+lineLayer的内容,最终的图像只包含ctx。。。

// if I render the contents to a view using the lines below, I see just CTX, lineLayer contents are not there
// remember CTX has an image and lineLayer has a transparent loaded PNG
// but when I render this, the final image contains just CTX's contents...
// this is how it is rendered.

CGContextDrawLayerInRect(ctx, superRect, lineLayer);
myView.image = UIGraphicsGetImageFromCurrentImageContext();