ios 图片保存到系统相册

- (void)saveImageToAlbum
{
    UIImageWriteToSavedPhotosAlbum(self.filterView.image, self, @selector(imageSavedToPhotosAlbum:didFinishSavingWithError:contextInfo:), nil);
}
- (void)imageSavedToPhotosAlbum:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
    NSString *message = @"";
    if (!error) {
        message = @"成功保存到相册";
    }else
    {
        message = [error description];
    }
    [XHToast showCenterWithText:message];
}