iOS图片的裁剪

- (void)tailoring {

    UIImage *oldImage = [UIImage imageNamed:@"实现准备裁剪的图片.png"];

    

    CGFloat borderW = 2;

    CGFloat imageW = oldImage.size.width + borderW * 2;

    CGFloat imageH = oldImage.size.height + borderW * 2;

    UIGraphicsBeginImageContextWithOptions(CGSizeMake(imageW, imageH), NO, 0.0);

    

    CGContextRef ctx = UIGraphicsGetCurrentContext();

    

    // 圆环

    CGFloat centerX = imageW * 0.5;

    CGFloat centerY = imageH * 0.5;

    CGContextAddArc(ctx, centerX, centerY, centerX, 0, M_PI * 2, 0);

    [[UIColor whiteColor] set];

    CGContextFillPath(ctx);

    

    // 裁剪

    CGFloat radius = oldImage.size.width * 0.5;

    CGContextAddArc(ctx, centerX, centerY, radius, 0, M_PI * 2, 0);

    CGContextClip(ctx);

    

    // 画图

    [oldImage drawInRect:CGRectMake(borderW, borderW, oldImage.size.width, oldImage.size.height)];

    

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    

    NSData *data = UIImagePNGRepresentation(newImage);

    [data writeToFile:@"路径/图片名.png" atomically:YES];

}