Ios 如何将视频下载到iPhone照片库？

我正在尝试从iPhone设备相册的URL下载视频。我做了以下代码。它可以与我的模拟器一起工作，但不能与实际的iOS设备一起工作。我用iPhone和iPad mini都试过了

这是我的密码

//Download method
- (IBAction)methodToDownload:(id)sender
{
     ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
     UISaveVideoAtPathToSavedPhotosAlbum([self   saveVideoToLocal], self, @selector(video:didFinishSavingWithError:contextInfo:), nil);
    library =   nil;
}




- (void)video:(NSString *) videoPath didFinishSavingWithError: (NSError *) error contextInfo: (void *) contextInfo
 {
    if(error)
       NSLog(@"didFinishSavingWithError: %@", error);
    else
    {
          UIAlertView *alertView  =   [[UIAlertView    alloc]initWithTitle:@"Download" message:@"Download completed." delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
         [alertView   show];

       //Delete File after creation
       NSFileManager *fileManager = [NSFileManager defaultManager];
       NSError *error;
       BOOL success = [fileManager removeItemAtPath:videoPath error:&error];
    if (success) {
        //            UIAlertView *removeSuccessFulAlert=[[UIAlertView alloc]initWithTitle:@"Congratulation:" message:@"Successfully removed" delegate:self cancelButtonTitle:@"Close" otherButtonTitles:nil];
        //            [removeSuccessFulAlert show];
        NSLog(@"Remove Completed");
    }
    else
    {
        NSLog(@"Could not delete file -:%@ ",[error localizedDescription]);
    }
  }
}

  //Save file to locally
  - (NSString *)saveVideoToLocal {
        NSArray       *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString  *documentsDirectory = [paths objectAtIndex:0];
        NSString  *filePath = [NSString stringWithFormat:@"%@/test.%@", documentsDirectory,@"mp4"];
        NSLog(@"filePath %@",filePath);


       //download the file in a seperate thread.
       dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
       NSLog(@"Downloading Started");

       NSURL  *url = [NSURL URLWithString:@"XYZ_MOVIE_URL.mov"];
       NSLog(@"URL is %@",url);
       NSData *urlData = [NSData dataWithContentsOfURL:url];
       if ( urlData )
       {
          //saving is done on main thread
          dispatch_async(dispatch_get_main_queue(), ^{
            [urlData writeToFile:filePath atomically:YES];

         });
      }

 });
 return filePath;
}

注意：不要忘记导入

#导入

注意：别忘了导入
\import
你说的“它不工作”是什么意思？你有错误吗？没有。但我的相册中没有任何视频。你尝试过跟踪吗？正在执行哪个If/else？是，正在尝试获取解决方案。在询问“为什么此代码不工作？”之前，请始终记住跟踪您的代码。根据S.O.的规定，这样的问题被认为是离题的。你说的“它不起作用”是什么意思？你有错误吗？没有。但我的相册中没有任何视频。你尝试过跟踪吗？正在执行哪个If/else？是，正在尝试获取解决方案。在询问“为什么此代码不工作？”之前，请始终记住跟踪您的代码。根据S.O.的规定，此类问题被视为离题。
// I am using simple way to download the video, You can use according to you.
NSURL *url = [NSURL URLWithString:@"yourfileURL"];
NSData *data = [NSData dataWithContentsOfURL:url];

// Write it to cache directory
NSString *path = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:@"file.mov"];
[data writeToFile:path atomically:YES];


// After that use this path to save it to PhotoLibrary

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library writeVideoAtPathToSavedPhotosAlbum:[NSURL fileURLWithPath:path] completionBlock:^(NSURL *assetURL, NSError *error) {

    if (error) {
        NSLog(@"%@", error.description);
    }else {
        NSLog(@"Done :)");
    }

}];