我有课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在哪里
#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，在其中获取所有数据。当下载一条数据时，我[self.delegate passProgress:fetchedItems/20.0f];由委托人调用，并且LoadViewController是这样的：
-(void)passProgress:(float)progress {
dispatch_async(dispatch_get_main_queue(), ^{
[self.progressView setProgress:progress];
NSLog(@"Updated!");
});
}
但问题是：下载了 20 个数据项中的一个后，progressView 没有更新。哪里有问题？