UIActivityIndicatorView冻结

Question

我有这个函数，它调用一个函数来检查CMS的信息。但是UIActivityIndicatorView会一直冻结，直到检查完成。不知道为什么。

编辑:有趣的是，我注释掉了性能选择器。UIActivityIndicatorView仍然冻结。直到我按下后退按钮，它才开始旋转...

我使用的是故事板，iOS 5

-(void)showLoading
{
    [activity startAnimating];
    //loading is a label to show "File Loading"
    loading.alpha =1;
    //is a label to show a 0.3 alpha of the label
    blackOverlay.hidden =0;
    [self performSelector:@selector(updateFromInternet:) withObject:@"a" afterDelay:2];  

    //[self updateFromInternet:@"a"];
}

-(void)updateFromInternet:(NSString *)urlStr

{   

    NSString *URLString = @"http://sites.google.com/site/iphonesdktutorials/xml/Books.xml";
    NSURL *updateDataURL = [NSURL URLWithString:URLString];    

    NSMutableURLRequest *WPXMLFetchRequest = [NSMutableURLRequest requestWithURL:updateDataURL];

    self.receivedData = [NSMutableData data];
    self.updateConnection = [NSURLConnection connectionWithRequest:WPXMLFetchRequest delegate:self];

    NSLog(@"Checking update at : %@", updateDataURL);

    //[self.updateConnection cancel];
}



-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    ////NSlog(@"Receiving data");
    [self.receivedData appendData:data];
}

-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    ////NSlog(@"Failed to receive data");
    self.receivedData = nil;
}

-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    ////NSlog(@"Received response from data");
    [self.receivedData setLength:0];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {

    NSString *data=[[NSString alloc]initWithData:self.receivedData encoding:NSUTF8StringEncoding];
    NSLog(@"data %@",data);

    NSError *parseError = nil;
    //NSDictionary *xmlDict = [XMLReader dictionaryForXMLData:self.receivedData error:&parseError];
    self.receivedDict = [XMLReader dictionaryForXMLData:self.receivedData error:&parseError];

    [self showDataOnScrollView];
}

Answer 1

你应该稍微延迟一下“重”函数，让活动指示器触发。尝试在延迟中添加2.0而不是2(我会使用一个小得多的值-比方说0.3)

[self performSelector:@selector(updateFromInternet:) withObject:@"a" afterDelay:0.3]; 

如果这不能解决您的问题，您应该查看(或发布)与代码中包含的额外内容相关的代码，如: loading.alpha =1；和blackOverlay.hidden =0；我假设它们是添加到活动指示器中的元素