为什么popViewController只能每隔一段时间工作一次

Question

我完全难过,这是情况:

我的应用程序使用Core Location框架获取用户的当前位置,然后将我的服务器ping TrailBehind用于附近有趣的地方并将其显示为列表.没问题.

为了节省电池,我从服务器获取数据后关闭了GPS服务.如果用户在使用应用程序时四处移动并想要一个新列表,则单击导航控制器上的"刷新"并再次激活CLLocation服务,将从服务器检索新的一批数据并重新绘制该表.

当应用程序从我的服务器抓取数据时,我加载了一个带有旋转地球仪的加载屏幕,上面写着"正在加载,请等待",我隐藏了导航栏,因此它们不会"返回".

因此,从服务器获取的初始数据可以完美无缺.

我第一次点击刷新所有代码执行以获取新位置,再次ping服务器以获取新的数据列表并更新单元格.但是,它应该恢复表视图的导航控制器栏,而不是加载表视图,但仍然在主窗口中显示我的加载视图.这只适用于设备,一切都在模拟器中完全正常.

第二次我点击刷新功能正常工作.

我点击刷新的第三次失败如上所述.

我点击刷新的第四次正常工作.

我点击刷新它的第五次失败如上所述.

等等,甚至刷新成功,奇怪的刷新失败.我逐行遍历所有代码,一切似乎正常执行.我其实继续加强对核心指令,庞大的单击"跳过之后"我发现表视图实际上在屏幕上某点CFRunLoopRunSpecific显示,但我然后单击"继续"和我加载视图接手屏幕.

我非常困惑.请帮忙!!非常感谢您的见解.

视频的奇怪行为:

相关守则:

RootViewControllerMethods(这是此TableView项目的基本视图)

- (void)viewDidLoad {
    //Start the Current Location controller as soon as the program starts.  The Controller calls delegate methods
    //that will update the list and refresh
    [MyCLController sharedInstance].delegate = self;
    [[MyCLController sharedInstance].locationManager startUpdatingLocation];
    lv = [[LoadingViewController alloc] initWithNibName:@"Loading" bundle:nil];
    [self.navigationController pushViewController:lv animated:YES];
    [super viewDidLoad];
}



- (void)updateClicked {
    //When the location is successfully updated the UpdateCells method will stop the CL manager from updating, so when we want to update the location
    //all we have to do is start it up again.  I hope.
    [[MyCLController sharedInstance].locationManager startUpdatingLocation];
    [self.navigationController pushViewController:lv animated:YES];
    //LV is a class object which is of type UIViewController and contains my spinning globe/loading view.
}



-(void)updateCells {
    //When the Core Location controller has updated its location it calls this metod.  The method sends a request for a JSON dictionary
    //to trailbehind and stores the response in the class variable jsonArray.  reloadData is then called which causes the table to
    //re-initialize the table with the new data in jsonArray and display it on the screen.  

    [[MyCLController sharedInstance].locationManager stopUpdatingLocation];

    if(self.navigationController.visibleViewController != self) {
        self.urlString = [NSString stringWithFormat:@"http://www.trailbehind.com/iphone/nodes/%@/%@/2/10",self.lat,self.lon];
        NSURL *jsonURL = [NSURL URLWithString:self.urlString];
        NSString *jsonData = [[NSString alloc] initWithContentsOfURL:jsonURL];
        NSLog(@"JsonData = %@ \n", jsonURL);
        self.jsonArray = [jsonData JSONValue];
        [self.tableView reloadData];
        [self.navigationController popToRootViewControllerAnimated:YES];
        [jsonData release];
    }
}

CLController方法:基本上只是将所有数据直接发送回RootViewController

// Called when the location is updated
- (void)locationManager:(CLLocationManager *)manager
    didUpdateToLocation:(CLLocation *)newLocation
           fromLocation:(CLLocation *)oldLocation
{
    NSLog(@"New Location: %@ \n", newLocation);
    NSLog(@"Old Location: %@ \n", oldLocation);
    @synchronized(self) {
        NSNumber *lat = [[[NSNumber alloc] init] autorelease];
        NSNumber *lon = [[[NSNumber alloc] init] autorelease];
        lat = [NSNumber numberWithFloat:newLocation.coordinate.latitude];
        lon = [NSNumber numberWithFloat:newLocation.coordinate.longitude];
        [self.delegate noteLat:lat];
        [self.delegate noteLon:lon];
        [self.delegate noteNewLocation:newLocation];
        [self.delegate updateCells];
    }
}

Answer 1

您可以尝试调试您的应用程序以查看调用 updateCells 时控件的位置吗？该应用程序似乎没有任何明显的问题。

确保在 LoadingViewController 类中没有内存警告。如果出现内存警告并且您的 RootViewController 的视图正在被释放，那么当您弹出到 RootViewController 时，viewDidLoad 将被再次调用。

在 viewDidLoad 和 updateCells 中保留断点。您确定没有在其他地方调用 LoadingViewController 吗？