将图片保存在指定目录

NSString  *pngPath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/Test.png"];
    NSString  *jpgPath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/Test.jpg"];
    [data writeToFile:jpgPath atomically:YES];
    [UIImagePNGRepresentation(image) writeToFile:pngPath atomically:YES];
    [UIImagePNGRepresentation(image) writeToFile:jpgPath atomically:YES];

将图片保存到相册

UIImageWriteToSavedPhotosAlbum(image, self, @selector(imageSavedToPhotosAlbum:didFinishSavingWithError:contextInfo:), nil);

- (void)imageSavedToPhotosAlbum:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
    NSString *message = @"呵呵";
    if (!error) {
        message = @"成功保存到相册";
    }else
    {
        message = [error description];
    }
    NSLog(@"message is %@",message);
}