[iOS] [Objective-C] S3の動画をカメラロールに保存する

iPhoneシミュレーターだと「The operation could not be completed.」と言われて失敗するが
実機だと保存できている。

NSURL *sourceURL = [NSURL URLWithString:@"https://s3.amazonaws.com/〜動画のpath〜.mp4"];
NSURLSessionTask *download = [[NSURLSession sharedSession] downloadTaskWithURL:sourceURL completionHandler:^(NSURL *location, NSURLResponse *response, NSError *error) {
    NSURL *documentsURL = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] firstObject];
    NSURL *tempURL = [documentsURL URLByAppendingPathComponent:[sourceURL lastPathComponent]];
    [[NSFileManager defaultManager] moveItemAtURL:location toURL:tempURL error:nil];
    UISaveVideoAtPathToSavedPhotosAlbum(tempURL.path, nil, NULL, NULL);
}];
[download resume];