progressView在今天的扩展中

Question

我在今天的扩展程序中有一个进度视图，显示下载的进度并且它可以正常工作，但这是第一次和下次打开扩展时虽然正在执行下载但是没有更新progressView。

@interface TodayViewController () <NCWidgetProviding>{
    NSURLSession * session;
    NSString * clipboard;
    NSString * jsonTitle;
}


@property (weak, nonatomic) IBOutlet UILabel *label;
@property (weak, nonatomic) IBOutlet UIProgressView *progressView;

@end

- (NSURLSession *) configureDownloadSession {
    if (!session) {
        NSURLSessionConfiguration * sessionConfiguration = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier: @"bgSessionConfiguration"];
        sessionConfiguration.sharedContainerIdentifier = @"group.myapp";
        sessionConfiguration.allowsCellularAccess = YES;
        session = [NSURLSession sessionWithConfiguration:sessionConfiguration delegate:self delegateQueue:nil];
    }
    return session;
}
session = [self configureDownloadSession];
            NSURLSessionDownloadTask * downloadTask = [session downloadTaskWithURL:[NSURL URLWithString:[[[json objectForKey:@"formats"] objectAtIndex:0] objectForKey:@"link"]]];
            jsonTitle=[[[json objectForKey:@"formats"] objectAtIndex:0] objectForKey:@"title"];
            [downloadTask resume];

- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite {

    float progress = (double)totalBytesWritten / (double)totalBytesExpectedToWrite;

    dispatch_async(dispatch_get_main_queue(), ^{
        NSLog(@"%f",progress);
        self.progressView.progress=progress;
        [mySharedDefaults synchronize];
    });
}