iOS 6 map 未显示提供的经纬度位置

Question

我在 UIViewController 中使用 map View ，并且提供了一个默认的放大位置以及注释。但是变焦不起作用。注释工作正常，但初始缩放到位置不起作用。

我不确定是什么原因导致了这个问题。任何帮助将不胜感激。

这是我的代码:

- (void)viewDidLoad
{
    [super viewDidLoad];

    MKCoordinateRegion myRegion;

    //Center
    CLLocationCoordinate2D center;
    center.latitude = 39.21516;
    center.longitude = -76.580806;

    //Span
    MKCoordinateSpan span;
    span.latitudeDelta = 0.02f;
    span.longitudeDelta = 0.02f;

    myRegion.center = center;
    myRegion.span = span;

    //set mapView
    [self.mapView setRegion:ascRegion animated:YES];

    //Annotation
    //Create coordinate for annotation
    CLLocationCoordinate2D theLocation;
    theLocation.latitude = 39.21516;
    theLocation.longitude = -76.580806;

    MyMapAnnotation * myAnnotation = [MyMapAnnotation alloc];
    myAnnotation.coordinate = theLocation;
    myAnnotation.title = @"I am here";
    myAnnotation.subtitle = @"This is where I am";

    [self.mapView addAnnotation:myAnnotation];
}

Answer 1

尝试关注this answer :

- (void)zoomToFitMapAnnotations:(MKMapView *)mapView { 
    if ([mapView.annotations count] == 0) return; 

    CLLocationCoordinate2D topLeftCoord; 
    topLeftCoord.latitude = -90; 
    topLeftCoord.longitude = 180; 

    CLLocationCoordinate2D bottomRightCoord; 
    bottomRightCoord.latitude = 90; 
    bottomRightCoord.longitude = -180; 

    for(id<MKAnnotation> annotation in mapView.annotations) { 
        topLeftCoord.longitude = fmin(topLeftCoord.longitude, annotation.coordinate.longitude); 
        topLeftCoord.latitude = fmax(topLeftCoord.latitude, annotation.coordinate.latitude); 
        bottomRightCoord.longitude = fmax(bottomRightCoord.longitude, annotation.coordinate.longitude); 
        bottomRightCoord.latitude = fmin(bottomRightCoord.latitude, annotation.coordinate.latitude); 
    } 

    MKCoordinateRegion region; 
    region.center.latitude = topLeftCoord.latitude - (topLeftCoord.latitude - bottomRightCoord.latitude) * 0.5; 
    region.center.longitude = topLeftCoord.longitude + (bottomRightCoord.longitude - topLeftCoord.longitude) * 0.5;      
    region.span.latitudeDelta = fabs(topLeftCoord.latitude - bottomRightCoord.latitude) * 1.1; 

    // Add a little extra space on the sides 
    region.span.longitudeDelta = fabs(bottomRightCoord.longitude - topLeftCoord.longitude) * 1.1; 

    region = [mapView regionThatFits:region]; 
    [mapView setRegion:region animated:YES]; 
}