關(guān)于給圖片設(shè)置圓角，普遍使用layer進(jìn)行處理，簡單方便；
但過多的渲染layer會導(dǎo)致降低app性能，拖慢了fps（特別是在cell中容易發(fā)覺）。

建議通過渲染畫布的方式實現(xiàn)：

分類：
@implementation UIImage (RoundedCorner)

 - (UIImage *)imageWithRoundedCornersAndSize:(CGSize)sizeToFit a ndCornerRadius:(CGFloat)radius {
     CGRect rect = (CGRect){0.f, 0.f, sizeToFit};
     UIGraphicsBeginImageContextWithOptions(sizeToFit, NO, UIScr een.mainScreen.scale);
     CGContextAddPath(UIGraphicsGetCurrentContext(),      
     [UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:radius].CGPath);     
     CGContextClip(UIGraphicsGetCurrentContext());
     [self drawInRect:rect];
     UIImage *output = UIGraphicsGetImageFromCurrentImageContext ();
     return output
}

- (void)drawRect:(CGRect)rect {
    CGRect bounds = self.bounds;      
   [[UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:8.0] addClip];[self.image drawInRect:bounds];
}
 
@end