iOS 为图片添加水印

+ (instancetype)waterMarkWithImage:(UIImage *)image andMarkImageName:(NSString *)markName{

    

    UIImage *watermarkImage = [UIImage imageNamed:markName];

    if (!watermarkImage) {

        NSLog(@"水印图片加载失败: %@", markName);

        return image;

    }

    

    // 获取原图尺寸和方向

    CGSize originalSize = image.size;

    BOOL isLandscape = originalSize.width > originalSize.height;

    

    // 根据图片方向设置不同的水印比例

    CGFloat watermarkRatio;

    if (isLandscape) {

        watermarkRatio = 0.04; // 横图水印比例

    } else {

        watermarkRatio = 0.06; // 竖图水印比例

    }

    

    CGFloat targetWidth = originalSize.width * watermarkRatio;

    CGFloat scaleFactor = targetWidth / watermarkImage.size.width;

    CGFloat watermarkWidth = watermarkImage.size.width * scaleFactor;

    CGFloat watermarkHeight = watermarkImage.size.height * scaleFactor;

    

    // 根据方向设置不同的边距

    CGFloat marginX, marginY;

    if (isLandscape) {

        marginX = originalSize.width * 0.02;

        marginY = originalSize.height * 0.02;

    } else {

        marginX = originalSize.width * 0.03;

        marginY = originalSize.height * 0.03;

    }

    

    // 创建图像上下文并绘制水印

    UIGraphicsBeginImageContextWithOptions(originalSize, NO, 0);

    [image drawInRect:CGRectMake(0, 0, originalSize.width, originalSize.height)];

    

    CGRect watermarkRect = CGRectMake(13,

                                     marginY-20,

                                     watermarkWidth,

                                     watermarkHeight);

    

    [watermarkImage drawInRect:watermarkRect blendMode:kCGBlendModeNormal alpha:1.0];

    

    UIImage *watermarkedImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    

    return watermarkedImage;

}