2

我使用后台线程从 url 加载注释。在我移动或缩放 mapView 之前，图钉不显示。如何更新我的视图？

我的 viewDidAppear

- (void)viewDidAppear:(BOOL)animated
{

[super viewDidAppear:animated];

//Create the thread 
[NSThread detachNewThreadSelector:@selector(loadPList) toTarget:self withObject:nil];

}

加载PList

- (void) loadPList { //Load the plist NSString *urlStr = [[NSString alloc] initWithFormat:@"http://www.domain.com/data.xml"];

NSURL *url = [NSURL URLWithString:urlStr]; NSDictionary *dict = [[NSDictionary alloc] initWithContentsOfURL:url];

NSMutableArray *annotations = [[NSMutableArray alloc]init];

NSArray *annotationsOnMap = mapView.annotations; if ([annotationsOnMap count] > [annotations count]) { [mapView removeAnnotations:annotationsOnMap];

} else { //Do nothing }

if ([[NSUserDefaults standardUserDefaults] boolForKey:@"blackKey"]) {

NSArray *ann = [dict objectForKey:@"Category1"];

for(int i = 0; i < [ann count]; i++) {

    NSString *coordinates = [[ann objectAtIndex:i] objectForKey:@"Coordinates"];

    double realLatitude = [[[coordinates componentsSeparatedByString:@","] objectAtIndex:1] doubleValue];
    double realLongitude = [[[coordinates componentsSeparatedByString:@","] objectAtIndex:0] doubleValue];

    MyAnnotation *myAnnotation = [[MyAnnotation alloc] init];
    CLLocationCoordinate2D theCoordinate;
    theCoordinate.latitude = realLatitude;
    theCoordinate.longitude = realLongitude;

    myAnnotation.coordinate=CLLocationCoordinate2DMake(realLatitude,realLongitude);

    myAnnotation.title = [[ann objectAtIndex:i] objectForKey:@"Name"];
    myAnnotation.subtitle = [[ann objectAtIndex:i] objectForKey:@"Address"];
    myAnnotation.icon = [[ann objectAtIndex:0] objectForKey:@"Icon"];


    [mapView addAnnotation:myAnnotation];
    [annotations addObject:myAnnotation];



}
}

else { //Do nothing }

//And same with other categories....

//Update the ui dispatch_async(dispatch_get_main_queue(), ^{

}); }
4

1 回答 1

4

您正在从非 UI 更新 UI - 线程这将不起作用

您将不得不调用在 UIThread 块中更新您的 ui 的代码段，如下所示：

例如

[mapView removeAnnotations:annotationsOnMap];

必须在 UI-Thread 中调用

   dispatch_async(dispatch_get_main_queue(), ^{
        //Update UI if you have to
        [mapView removeAnnotations:annotationsOnMap];
    });

请注意，您必须在 main_queue 线程中调用所有 UI 更新

   dispatch_async(dispatch_get_main_queue(), ^{
        //All UI updating code must come here
    });
于 2012-06-02T14:15:35.973 回答