UIImage Category

UIImage+Border.m

+ (UIImage *)rt_borderImageWithBorderColor:(UIColor *)borderColor fillColor:(UIColor *)fillColor borderWidth:(CGFloat)width radius:(CGFloat)radius forCorner:(UIRectCorner)corner
{
    const CGFloat length = MAX(3, 2 * MAX(radius, width / 2) + width + 1.f / [UIScreen mainScreen].scale);
    UIGraphicsBeginImageContextWithOptions(CGSizeMake(length, length), NO, 0);
    [borderColor ?: [UIColor clearColor] setStroke];
    [fillColor ?: [UIColor clearColor] setFill];
    
    UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(width / 2, width / 2, length - width, length - width)
                                               byRoundingCorners:corner
                                                     cornerRadii:CGSizeMake(radius, radius)];
    
    path.lineWidth = width;
    if (radius >= 1.f / [UIScreen mainScreen].scale && (corner & UIRectCornerTopLeft) == UIRectCornerTopLeft) {
        path.lineCapStyle = kCGLineCapRound;
    }
    else {
        path.lineCapStyle = kCGLineCapSquare;
    }
    [path fill];
    [path stroke];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    const CGFloat padding = MAX(MAX(radius, width / 2) + width / 2, 1);
    return [image resizableImageWithCapInsets:UIEdgeInsetsMake(padding, padding, padding, padding)
                                 resizingMode:UIImageResizingModeStretch];
}