IOS: UIImageView border white with radius display a strange dark line in 4 corners

Question

I set the border white and radius for my ImageView. But in 4 corner of the ImageView, some dark line appear.
Here is the code I set the color

Answer 1

Actually you have to use two layers.

self.image.clipsToBounds = YES;
UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:self.image.bounds byRoundingCorners:UIRectCornerAllCorners cornerRadii:CGSizeMake(48, 48)];
CAShapeLayer *maskLayer = [CAShapeLayer layer];
maskLayer.frame = self.image.bounds;
maskLayer.path = maskPath.CGPath;
maskLayer.strokeColor = [UIColor redColor].CGColor;

self.image.layer.mask = maskLayer;

CAShapeLayer*   frameLayer = [CAShapeLayer layer];
frameLayer.frame = self.image.bounds;
frameLayer.path = maskPath.CGPath;
frameLayer.strokeColor = [UIColor whiteColor].CGColor;
frameLayer.fillColor = nil;
frameLayer.lineWidth = 20;
[self.image.layer addSublayer:frameLayer];