异常：'无效区域'当尝试显示地图时

Question

当我尝试显示地图时，出现以下异常：

由于未捕获的异常“NSInvalidArgumentException”而终止应用程序，原因：“无效区域

”

我的相关代码是这样的：

-(void)viewWillAppear:(BOOL)animated
{   
    [mapView removeAnnotations:mapView.annotations];
    
    // locationManager update as location
    locationManager = [[CLLocationManager alloc] init];
    locationManager.delegate = self; 
    locationManager.desiredAccuracy = kCLLocationAccuracyBest; 
    locationManager.distanceFilter = kCLDistanceFilterNone; 
    [locationManager startUpdatingLocation];
    CLLocation *location = [locationManager location];
    //Configure the new event with information from the location
    CLLocationCoordinate2D coordinate = [location coordinate];
    
    latitudeOfUserLocation=coordinate.latitude;
    longitudeOfUserLocation=coordinate.longitude;
    
    location2D = (CLLocationCoordinate2D){ .latitude = latitudeOfUserLocation, .longitude = longitudeOfUserLocation };
    MyLocation *annotation=[[[MyLocation alloc]initWithName:@"You are here" distanceVersLaStation:@"" coordinate:location2D]autorelease];
    annotation.pinColor = MKPinAnnotationColorRed;  
    [mapView addAnnotation:annotation];
    
    MKCoordinateSpan span={latitudeDelta:1,longitudeDelta:0.5};
    MKCoordinateRegion region={location2D,span};
    [mapView setRegion:region];

}

编辑

我尝试按照您在评论中所说的方式进行操作。异常已解决，但是，当我尝试在控制台中显示用户的经度/纬度时，我什么也得不到。这是我的代码，大部分是正确的：

    -(void)viewWillAppear:(BOOL)animated
    {  
            
        [mapView removeAnnotations:mapView.annotations];
        
        // locationManager update as location
        locationManager = [[CLLocationManager alloc] init];
        locationManager.delegate = self; 
        locationManager.desiredAccuracy = kCLLocationAccuracyBest; 
        locationManager.distanceFilter = kCLDistanceFilterNone; 
        [locationManager startUpdatingLocation];
        NSURL *url=[NSURL         URLWithString:@"http://ipho.franceteam.org/ad_V1/stations/"];
    ASIFormDataRequest * request=[ASIFormDataRequest requestWithURL:url];
[request setPostValue:[NSNumber numberWithFloat:longitudeOfUserLocation] forKey:@"longitude"];
    [request setDelegate:self];
    [request startAsynchronous];
    MBProgressHUD *hud=[MBProgressHUD showHUDAddedTo:self.view animated:YES];
    hud.labelText=@"Recherche en cours..";// this never stop loading

    }

-(void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
    CLLocation *location = [locationManager location];
    //Configure the new event with information from the location
    CLLocationCoordinate2D coordinate = [location coordinate];
    latitudeOfUserLocation=coordinate.latitude;
    longitudeOfUserLocation=coordinate.longitude;
    NSLog(@"your latitude :%f",latitudeOfUserLocation);//here nothing is shown
    NSLog(@"your longitude :%f",longitudeOfUserLocation);// and here too
    location2D = (CLLocationCoordinate2D){ .latitude = latitudeOfUserLocation, .longitude = longitudeOfUserLocation };
    MyLocation *annotation=[[[MyLocation alloc]initWithName:@"Vous êtes ici" distanceVersLaStation:@"" coordinate:location2D]autorelease];
    annotation.pinColor = MKPinAnnotationColorRed;  //or red or whatever
    [mapView addAnnotation:annotation];
    //
    MKCoordinateSpan span={latitudeDelta:1,longitudeDelta:0.5};
    MKCoordinateRegion region={location2D,span};
    [mapView setRegion:region];

}//End function

即使我在模拟器上工作，我也应该在控制台上得到一些东西，对吗？

再次编辑

嗨，我有机会在 iPhone（设备）上测试我的代码，我注意到当我尝试搜索时，应用程序已成功跟踪我的位置并找到符合我搜索的电台（紫色注释）但是，地图并未显示，搜索进度仍在加载，永不停止。

hud.labelText=@"Recherche en cours..";// this never stop loading

这是可以更好解释的屏幕截图：

Answer 1

“Invalid Region”异常通过，因为您设置给mapView的区域无效。据我所知，有两个原因会导致此异常：区域的中心点无效，或者区域的跨度无效。

要避免此异常：
1) 检查中心点值：纬度在[-90;90]范围内，经度在[-180;180]范围内
2) 使用 [mapView regionThatFits:region] 获取具有有效跨度的区域，然后设置为 mapview:
[mapView setRegion:[mapView regionThatFits:region]]

Answer 2

在某些情况下（当应用程序从后台变为活动状态时）didUpdateUserLocation 方法会被触发，但不会更新位置。在这些情况下，没有有效区域，并且 setRegion: 方法可能会抛出异常。
愚蠢的是，一个简单的解决方案可以在设置之前检查其区域是否有效：

 if(region.center.longitude == -180.00000000){
    NSLog(@"Invalid region!");
}else{
    [aMapView setRegion:region animated:YES];
}

Answer 3

调用 startUpdatingLocation 后，位置可能需要几秒钟的时间才能更新，因此您无法在之后立即尝试检索它。在更新之前，位置包含无效值，这就是错误告诉您的内容。

相反，实现 locationManager:didUpdateToLocation:fromLocation: 委托方法并读取其中的位置。

将 startUpdatingLocation 之后的所有代码移至该方法：

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
    CLLocation *location = [locationManager location];
    //etc...
}

注意： 上面的方法已被贬值：

Answer 4

[mapView setRegion:[mapView regionThatFits:region] animated:TRUE];

Answer 5

不能大于180

CLLocationDegrees delta = MAX(maxLatitude - minLatitude, maxLongitude - minLongitude) * 1.1;

delta = points.count < 2 ? 0.5 : delta;
delta = MIN(delta, 180);

CLLocationDegrees centerX = (maxLatitude-minLatitude)/2.0 + minLatitude;
CLLocationDegrees centerY = (maxLongitude-minLongitude)/2.0 + minLongitude;

CLLocationCoordinate2D theCoordinate = {centerX,centerY};
MKCoordinateSpan span = MKCoordinateSpanMake(delta, delta);
self.mapView.region = MKCoordinateRegionMake(theCoordinate, span);