CALayer cornerRadius has no effect on 4" device (simulator) - objective-c

Question

I work on dynamically, programmatically layout a view for 3.5" devices as well as for 4" devices.
As such that works fine.
But I want rounded corners so that my images appear like playing cards.
And I get rounded corners nicely displayed in 3,5 inch devices on the simulator for simulated iOS 6.1 and 7 alike.
But when I choose iPhone retina 4 inch on 6.1 or 7, then the UIImage in the UIImageView is fully displayed.
It works nicely on simulated iPad devices (in iPhone simulation mode - it is an iPhone only app).
As for today, I do not have any 4" device with me to test it. I can test on a device during the upcoming week.
Hiere is the relevant code:
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
self.imageV.image = self.image; // The image property was set by the caller.
// Layout imageV within self.view with a margin of MARGIN
self.imageV.frame = CGRectMake(self.view.frame.origin.x + MARGIN, self.view.frame.origin.y + MARGIN, self.view.frame.size.width - 2 * MARGIN, self.view.frame.size.height - 2 * MARGIN);
// set the raidus and the mask to follow the rounded corners.
self.imageV.layer.cornerRadius = CORNER_RADIUS;
self.imageV.layer.masksToBounds = YES;
}
BTW: CORNER_RADIUS is 18 and MARGIN is 15. Changing these values has no effect on the issue.
UPDATE: Thanks to Matt I figured out that the problem disappears when I create the UIImageView programmatically. That is some really nice workaround plus it points into the right diretion, I guess, but it is not a solution. Any ideas what setting in the storyboard editor might have caused the problem?
As far as I can see, auto layout is disabled for all view controllers in this storyboard.

Answer 1

The answer is simple. The code did work. It did add round corners to the UIImageView object and the maskToBounds worked well.
But the actual image displayed is smaller. I used AspectFit as mode to ensure that the actual image is not squeesed but displayed in its original aspect ration. Because of the longer layout of the iPhone5 dimensions the image only filled a part of its owning UIImageView. I changed the background color to gray for the screenshot and now it gets clear.
So the solution will be that I'll have to calculate the proper size of the image view so that it matches exactly the size of the scaled image. Then it should work.
(I'll update this answer when it is done).
Update: this is what I finally did: I removed the UIImageView from the Storyboard and deal with it programmatically.
Don't get confused by the complexity. I added another view just to throw a shadow, although this is not related to the original question. The shadow I wanted to add anyway. And it turned out that CALayer's shadow and masksToBounds=YES don't really agree on. That is why I added a regular UIView which lies in between the card view and the background view.
Finally this is so much of a hassle for displaying a simple rectangle image, that I think, just subclassing UIView and drawing everything with openGL or so directly into the CALayer would be probably much easier. :-)
Anyway, this is my code:
- (void)viewDidLoad {
[super viewDidLoad];
self.state = #0;
// Create an image view to carry the image with round rects
// and create a regular view to create the shadow.
// Add the shadow view first so that it appears behind
// the actual image view.
// Explanation: We need a separate view for the shadow with the same
// dimenstions as the imageView. This is because the imageView's image
// is rectangular and will only be clipped to round rects when the
// property masksToBounds is set to YES. But this setting will also
// clip away any shadow that the imageView's layer may have.
// Therfore we add a separate mainly empty UIView just behind the
// UIImageview to throw the shadow.
self.shadowV = [[UIView alloc] init];
self.imageV = [[UIImageView alloc] initWithImage:self.image];
[self.view addSubview:self.shadowV];
[self.shadowV addSubview:self.imageV];
// set the raidus and the mask to follow the rounded corners.
[self.imageV.layer setCornerRadius:CORNER_RADIUS];
[self.imageV.layer setMasksToBounds:YES];
[self.imageV setContentMode:UIViewContentModeScaleAspectFit];
// set the shadows properties
[self.shadowV.layer setShadowColor:[UIColor blackColor].CGColor];
[self.shadowV.layer setShadowOpacity:0.4];
[self.shadowV.layer setShadowRadius:3.0];
[self.shadowV.layer setShadowOffset:CGSizeMake(SHADOW_OFFSET, SHADOW_OFFSET)];
[self.shadowV.layer setCornerRadius:CORNER_RADIUS];
[self.shadowV setBackgroundColor:[UIColor whiteColor]]; // The view needs to have some content. Otherwise it is not displayed at all, not even its shadow.
}
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
// Just to be save
if (!self.image) {
return;
}
self.imageV.image = self.image; // The image property was set by the caller.
// Layout imageV within self.view with a margin of MARGIN
self.imageV.frame = CGRectMake(MARGIN, MARGIN, self.view.bounds.size.width - 2 * MARGIN, self.view.bounds.size.height - 2 * MARGIN);
// Calculate the size and position of the image and set the image view to
// the same dimensions
// This works under the assumption, that the image content mode is aspectFit.
// Well, as we are doing so much of the layout manually, it would work with a number of content modes. :-)
float imageWidth, imageHeight;
float heightWidthRatioImageView = self.view.frame.size.height / self.view.frame.size.width;
float heightWidthRatioImage = self.image.size.height / self.image.size.width;
if (heightWidthRatioImageView > heightWidthRatioImage) {
// The ImageView is "higher" than the image itself.
// --> The image width is set to the imageView width and its height is scaled accordingly.
imageWidth = self.imageV.frame.size.width;
imageHeight = imageWidth * heightWidthRatioImage;
} else {
// The ImageView is "wider" than the image itself.
// --> The image height is set to the imageView height and its width is scaled accordingly.
imageHeight = self.imageV.frame.size.height;
imageWidth = imageHeight / heightWidthRatioImage;
}
// Layout imageView and ShadowView accordingly.
CGRect imageRect =CGRectMake((self.view.bounds.size.width - imageWidth) / 2,
(self.view.bounds.size.height - imageHeight) / 2,
imageWidth, imageHeight);
[self.shadowV setFrame:imageRect];
[self.imageV setFrame:CGRectMake(0.0f, 0.0f, imageWidth, imageHeight)]; // Origin is (0,0) because it overlaps its superview which just throws the shadow.
}
And this is how it finally looks like:

Answer 2

The problem is due to some issue with code or configuration you have not told us about. Proof: I ran the following and it works fine. Note that I create the image view in code (to avoid the auto layout problem) and fixed your frame/bounds confusion, and that I've skipped your self.image, but none of that is really relevant to the issue you are seeing:
#define CORNER_RADIUS 18
#define MARGIN 15
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
self.imageV = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"im"]];
[self.view addSubview:self.imageV];
// Layout imageV within self.view with a margin of MARGIN
self.imageV.frame = CGRectMake(self.view.bounds.origin.x + MARGIN, self.view.bounds.origin.y + MARGIN, self.view.bounds.size.width - 2 * MARGIN, self.view.bounds.size.height - 2 * MARGIN);
// set the raidus and the mask to follow the rounded corners.
self.imageV.layer.cornerRadius = CORNER_RADIUS;
self.imageV.layer.masksToBounds = YES;
}
It works fine (and you can prove that to yourself). Here is a screen shot of the 4-inch simulator:
Therefore the problem is outside the code that you quote in your question, and cannot be analyzed without further information.