在iPad视网膜模式下，CAShapeLayer不会在模拟器中绘制

Question

I have a small piece of code, that draws a circle as CAShapeLayer:

- (void) viewWillAppear:(BOOL)animated {
    CGFloat size = MIN(self.view.frame.size.width, self.view.frame.size.height);
    CAShapeLayer *circleLayer = [CAShapeLayer layer];
    circleLayer.fillColor = [[UIColor redColor] CGColor];
    circleLayer.frame = CGRectMake((self.view.frame.size.width - size) / 2.0 ,(self.view.frame.size.height - size) / 2.0, size, size);
    CGMutablePathRef pathRef = CGPathCreateMutable();
    CGPathAddEllipseInRect(pathRef, NULL, CGRectMake(0, 0, size, size));
    circleLayer.path = pathRef;
    CGPathRelease(pathRef);

    [self.view.layer addSublayer:circleLayer];
}

The circle is shown correctly on iPad 2 and in simulator in non-retina mode. When I switch the simulator into retina mode, the circle is not shown at all. Unfortunately, I don't have an actual iPad 3 yet, so I cannot say, if it works on actual device. Can anyone exlain, what I am doing wrong?

Update: I reported this as a bug to Apple. They told me, that the bug is duplicate and the other bug was still open. After a while it got closed, but after the last XCode update it is still reproducible

Update 2: Checked it on a real iPad 3. Works correctly.

Answer 1

Indeed! With your code, if circleLayer 's size is 512 or above, the circle won't display on the Simulator's retina iPad...

Now, given that I want to be able to sleep peacefully tonight, here's a workaround that uses CALayer's cornerRadius property to do the trick:

-(void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated]; //always call super

    CGFloat size = MIN(self.view.frame.size.width, self.view.frame.size.height);
    NSLog(@"size: %f", size);

    CALayer *circleLayer = [CALayer layer];
    [circleLayer setBackgroundColor:[UIColor redColor].CGColor];
    circleLayer.frame = CGRectMake((self.view.frame.size.width - size) / 2.0 ,(self.view.frame.size.height - size) / 2.0, size, size);

    circleLayer.cornerRadius = size/2;

    [self.view.layer addSublayer:circleLayer];
}

This will display the same circle in the iPad retina Simulator too.