1.代码很简单,主要是要注意配色问题(比如说黑色背景就用白色水印,白色就用黑色)

上代码

//添加水印,返回一个和屏幕等大的水印
+ (UIImageView *)addWatermark
{
    static UIImageView * imageView = nil;
    if (imageView) {
        [imageView removeFromSuperview];
        return imageView;
    }

    NSString *str = @"wangyebin";
    if ([str isEqualToString:@""]) {
        return nil;
    }

    CGSize size = [UIScreen mainScreen].bounds.size;
    UIGraphicsBeginImageContext(size);

    [str drawInRect:CGRectMake(10, 20, size.width, 50) withAttributes:@{NSFontAttributeName:[UIFont fontWithName:@"Marker Felt" size:30],NSForegroundColorAttributeName:[UIColor colorWithRed:1 green:1 blue:1 alpha:1]}];
    [str drawInRect:CGRectMake(10, size.height/2, size.width, 50) withAttributes:@{NSFontAttributeName:[UIFont fontWithName:@"Marker Felt" size:30],NSForegroundColorAttributeName:[UIColor colorWithRed:0 green:0 blue:0 alpha:0.8]}];
    [str drawInRect:CGRectMake(10, size.height-50, size.width, 50) withAttributes:@{NSFontAttributeName:[UIFont fontWithName:@"Marker Felt" size:30],NSForegroundColorAttributeName:[UIColor colorWithRed:1 green:1 blue:0 alpha:0.8]}];

    //返回绘制的新图形
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    imageView = [[UIImageView alloc]initWithFrame:[UIScreen mainScreen].bounds];
    imageView.image = newImage;
    imageView.alpha = 0.005;

    return imageView;
}

原创: 转载请注明出处 http://www.jianshu.com/p/ba9bf641dafc