ios - 为 UIImage 添加白色边框

Question

<分区>

Answer 1

您可以通过访问 UIImageView 的图层属性来设置 CALayer 的边框属性。

首先，添加Quartz

#import <QuartzCore/QuartzCore.h>

设置属性:

[[yourImageView layer] setBorderWidth:2.0f];
[[yourImageView layer] setBorderColor:[UIColor whiteColor].CGColor];

编辑1

因为你需要保存带边框的图片，使用下面的。

- (UIImage *)addBorderToImage:(UIImage *)image {
    CGImageRef bgimage = [image CGImage];
    float width = CGImageGetWidth(bgimage);
    float height = CGImageGetHeight(bgimage);

        // Create a temporary texture data buffer
    void *data = malloc(width * height * 4);

    // Draw image to buffer
    CGContextRef ctx = CGBitmapContextCreate(data,
                                                 width,
                                                 height,
                                                 8,
                                                 width * 4,
                                                 CGImageGetColorSpace(image.CGImage),
                                                 kCGImageAlphaPremultipliedLast);
    CGContextDrawImage(ctx, CGRectMake(0, 0, (CGFloat)width, (CGFloat)height), bgimage);

    //Set the stroke (pen) color
    CGContextSetStrokeColorWithColor(ctx, [UIColor greenColor].CGColor);

    //Set the width of the pen mark
    CGFloat borderWidth = (float)width*0.05;
    CGContextSetLineWidth(ctx, borderWidth);

    //Start at 0,0 and draw a square
    CGContextMoveToPoint(ctx, 0.0, 0.0);    
    CGContextAddLineToPoint(ctx, 0.0, height);
    CGContextAddLineToPoint(ctx, width, height);
    CGContextAddLineToPoint(ctx, width, 0.0);
    CGContextAddLineToPoint(ctx, 0.0, 0.0);

    //Draw it
    CGContextStrokePath(ctx);

        // write it to a new image
    CGImageRef cgimage = CGBitmapContextCreateImage(ctx);
    UIImage *newImage = [UIImage imageWithCGImage:cgimage];
    CFRelease(cgimage);
    CGContextRelease(ctx);

        // auto-released
    return newImage;
}

Reference