绘图quartz之加水印

实现在图片上加一个水印  并存在document的路径下  同时在手机相册中也存一份

//首先开启imageContext找到图片

    UIGraphicsBeginImageContext(self.imageView.frame.size);     //找到图片     UIImage *img = [UIImage imageNamed:@"0.png"];     //画图片的位置     [img drawInRect:self.imageView.bounds];     //设置水印文字     NSString *str = @"hi";     [str drawAtPoint:CGPointMake(100, 100) withAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:30],NSForegroundColorAttributeName:[UIColor blackColor],}];     //从当前的图形的上下文获得图片     self.image = UIGraphicsGetImageFromCurrentImageContext();     //结束imageContext     UIGraphicsEndImageContext();

    [self.imageView setImage:self.image];

//将画的图片存到document目录中//////////////     //获得document的路径     NSString *documentPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)lastObject];     NSLog(@"%@",documentPath);     //在document中设置文件的名字     NSString *fileName = [documentPath stringByAppendingPathComponent:@"my.png"];     //创建data 暂存图片     NSData *imageData =UIImagePNGRepresentation(self.image);     [imageData writeToFile:fileName atomically:YES]; //将图片存在手机的相册中中////////////////     UIImageWriteToSavedPhotosAlbum(self.image, nil, nil, nil);