目标c ProgressView无法正确更新

Question

我正在使用表格视图，用户可以在其中下载视频文件。当我下载文件时，除了progressView之外，其他一切都正常。但是最后，我仍然准备好播放文件。 我对目标C中的请求不是很熟悉，因此我可能在代码中的某个时候搞砸了。有人能看到其中的错误吗？

另一个奇怪的是，我没有得到最后的NSLog（在connectionDidFinishLoading方法内部）

以下是影响下载的代码部分：

NSURLSession *session;
UIProgressView *progressBar;
BOOL currentlyDownloading;
NSString *videoToPlay;
BOOL downloadFinished;
- (void)viewDidLoad {
   [super viewDidLoad];
   session = [NSURLSession sharedSession];
   currentlyDownloading = false;
   downloadFinished = false;
   videoToPlay = @"";
}

-(NSArray *)findFiles:(NSString *)extension
{
NSMutableArray *matches = [[NSMutableArray alloc]init];
NSFileManager *manager = [NSFileManager defaultManager];

NSString *item;
NSArray *contents = [manager contentsOfDirectoryAtPath:[NSHomeDirectory() stringByAppendingPathComponent:@"Documents"] error:nil];
for (item in contents)
{
    if ([[item pathExtension]isEqualToString:extension])
    {
        [matches addObject:item];
    }
}

return matches;
}

 - (VideoTableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
VideoTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"videoTuto" forIndexPath:indexPath];

if(indexPath.row == 0){
    //local stream
    cell.videoName.text = @"test local";
    NSFileManager *fileManager = [NSFileManager defaultManager];

    NSString *urlPathStr = [[NSBundle mainBundle] pathForResource:@"test" ofType:@"mp4"];
    NSLog(@"urlpathstr: %@",urlPathStr);
    if ([fileManager fileExistsAtPath:urlPathStr]){
        NSLog(@"file exists");
        cell.downloadState.image = [UIImage imageNamed:@"downloaded"];
        cell.downloaded = [NSNumber numberWithBool:YES];
    }else{
        NSLog(@"file doesn't exist need to dwl it...");
        cell.downloadState.image = [UIImage imageNamed:@"download"];
        cell.downloaded = [NSNumber numberWithBool:NO];
      }
         cell.video = urlPathStr;
     }else{
         //server stream
         cell.videoName.text = @"test server";
         NSFileManager *fileManager = [NSFileManager defaultManager];

         NSString *urlPathStr = [[NSBundle mainBundle] pathForResource:@"tastege" ofType:@"mp4"];
         NSLog(@"urlPathStr: %@",urlPathStr);
         BOOL asVideo = false;
         NSArray *videosStored = [self findFiles:@"mp4"];
         for (NSInteger i = 0; i<[videosStored count]; i++) {
             NSLog(@"obj at idx %lu : %@",i,[videosStored objectAtIndex:i]);
             if([[videosStored objectAtIndex:i] isEqualToString:@"tastege.mp4"]){
                  asVideo = true;
             }
         }
         if ([fileManager fileExistsAtPath:urlPathStr] || asVideo){
             NSLog(@"file exists");
             cell.downloadState.image = [UIImage imageNamed:@"downloaded"];
             cell.downloaded = [NSNumber numberWithBool:YES];
             NSString *fileName = @"tastege.mp4";
             NSString *documentDir =   [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
            NSString *filePath = [documentDir   stringByAppendingPathComponent:fileName];
             cell.video = filePath;
        }else{
            NSLog(@"file doesn't exist need to dwl it...");
            cell.downloadState.image = [UIImage imageNamed:@"download"];
            cell.downloaded = [NSNumber numberWithBool:NO];
        }
    }
    // Configure the cell...
    return cell;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
    VideoTableViewCell *cell = [[tableView visibleCells]     objectAtIndex:indexPath.row];
    if(cell.downloaded == [NSNumber numberWithBool:YES]){
        NSLog(@"show vid");
        videoToPlay = cell.video;
        NSLog(@"cell.video: %@",cell.video);
        NSLog(@"videoToPlay: %@",videoToPlay);
        [self performSegueWithIdentifier:@"showVid" sender:self];
    }else if(!currentlyDownloading){
        //start download
        currentlyDownloading = true;
        __block BOOL postRequestReturned = false;
        progressBar = cell.progress;
        progressBar.hidden = NO;
        NSString *fileName = @"tastege.mp4";
        NSString *documentDir =      [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
        NSString *filePath = [documentDir stringByAppendingPathComponent:fileName];
        NSString *videoUrl = [NSString stringWithFormat:@"MYURL/%@",fileName];

        NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
        [request setURL:[NSURL URLWithString:videoUrl]];
        [request setHTTPMethod:@"GET"];
        NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error){
            if(data == nil){
                NSLog(@"ERROR: %@", error.description);
            }else{
               [data writeToFile:filePath atomically:YES];
                NSLog(@"File is saved to %@",filePath);
                currentlyDownloading = false;
            }

            postRequestReturned = true;
        }];
        [task resume];

    }
}


- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition disposition))completionHandler {
    completionHandler(NSURLSessionResponseAllow);
    [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
    progressBar.hidden = NO;
    progressBar.progress=0.0f;
    _downloadSize=[response expectedContentLength];
    _dataToDownload=[[NSMutableData alloc]init];
}

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data {
    [_dataToDownload appendData:data];
    progressBar.progress=((float)[ _dataToDownload length ]/(float)_downloadSize);
}

- (void) connectionDidFinishLoading:(NSURLConnection *)connection {
    NSLog(@"Succeeded! Received %lu bytes of data",(unsigned long).  [_dataToDownload length]);
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
    progressBar.hidden = YES;
    downloadFinished = true;


    [self.tableView beginUpdates];
    NSArray *indexs = self.tableView.indexPathsForVisibleRows;
    [self.tableView reloadRowsAtIndexPaths:indexs     withRowAnimation:UITableViewRowAnimationNone];
    [self.tableView endUpdates];
}

非常感谢。

PS：我的代表团如下：UITableViewController <NSURLSessionDataDelegate, NSURLSessionDelegate, NSURLSessionTaskDelegate> 据我所知，已经正确实施了