iOS 保存图片到相册

- (void)saveToPhotosAlbumWithImage:(UIImage *)image {
    UIImageWriteToSavedPhotosAlbum(image, self, @selector(image:didSavedWithError:contextInfo:), (__bridge void *)self);
}

// 如果 error 为 nil，表明保存成功
- (void)image:(UIImage *)image didSavedWithError:(NSError *)error contextInfo:(void *)contextInfo {

    NSLog(@"image = %@, error = %@, contextInfo = %@", image, error, contextInfo);
}