Question

我上课LoadViewController，一开始我称之为：

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.

dispatch_async(kBgQueue, ^{

    NSData *dataOfURL = [NSData dataWithContentsOfURL:kRSSURL];

    [self performSelectorOnMainThread:@selector(fetchedData:) withObject:dataOfURL waitUntilDone:YES];
});
}

kbgQueue

的位置

   #define kBgQueue dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)

在主线程上执行fetchedData:。

- (void)fetchedData:(NSData *)responseData {

XMLParser *parser = [[XMLParser alloc] initWithData:responseData];
parser.delegate = self;

if ([parser parse]) {

    // if parsed.
    if (!data) {

        data = [[NSMutableArray alloc] init];
    }
    else {

        [data removeAllObjects];
    }

    data = [parser getParsedData];

    ViewController *viewController = [self.storyboard instantiateViewControllerWithIdentifier:@"ViewController"];
    viewController.array = data;

    [self presentViewController:viewController animated:YES completion:^{}];
    //[self reloadData];
}
else {

    NSLog(@"False.");
}

}

如您所见，我使用自己的XMLParser帮助程序类，我可以获取所有数据。当下载一个数据时，我会通过委托调用[self.delegate passProgress:fetchedItems/20.0f];，而LoadViewController就像这样：

-(void)passProgress:(float)progress {

dispatch_async(dispatch_get_main_queue(), ^{
    [self.progressView setProgress:progress];
    NSLog(@"Updated!");
});
}

但问题是：在下载一个20个数据项后，progressView没有更新。问题在哪里？

Answer 1

我不知道它是否正确但我在LoadViewController从perfromOnMainThread:withObject:waitUntilDone:更改为perfromInBackground:withObject:，但它确实有效。

如何在objective-C中正确更新UIProgressView

1 个答案: