MapView只加载两次，然后没有MAP出现，只有黄色背景

Question

当应用加载时，Mapview会成功加载。

然后，在第一次更改视图并返回主视图并且viewDidAppear初始化之后，Mapview会成功加载。

但是在viewDidAppear的第一个实例之后，mapview地图不会加载，背景为黄色。我必须在mapview地图再次出现之前重新启动应用程序。

这是因为我在更改视图时没有正确发布mapview吗？我正在使用ARC。

编辑（katzenhut）：OP在评论中发布了此代码： Appdelegate.m

if(self.locationManager==nil){
     _locationManager=[[CLLocationManager alloc] init];
     _locationManager.delegate=self;
     self.locationManager = _locationManager;
 }

Viewcontroller.m

- (void)viewDidAppear:(BOOL)animated{


    [self setValuesFromPreferences];
    appDelegate.refresh = FALSE;
    theMapView.showsUserLocation = YES;
    [theMapView setCenterCoordinate:appDelegate.locationManager.location.coordinate   zoomLevel:zoom animated:YES];
    [super viewDidAppear:animated];
}

- (void)mapView:(MKMapView *)mapView didUpdateUserLocation:(MKUserLocation *)userLocation{
    [theMapView setCenterCoordinate: appDelegate.locationManager.location.coordinate zoomLevel:zoom animated: YES];
}

Mapviewcontroller.m

#import "MapViewController.h"


@implementation MapViewController
@synthesize theMapView;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
    // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    appDelegate = (theAppDelegate *)[UIApplication sharedApplication].delegate;
    [super viewDidLoad];

}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];

}
- (void)viewDidAppear:(BOOL)animated
{
    theMapView.showsUserLocation = YES;
    pendingRegionChange = YES;
    isTracking = YES;
    [theMapView setCenterCoordinate:appDelegate.locationManager.location.coordinate zoomLevel:14 animated:YES];
    [super viewDidAppear:animated];


}

-(void)mapView:(MKMapView *)mapView didUpdateUserLocation:(MKUserLocation *)userLocation
{
    if( isTracking )
    {
        pendingRegionChange = YES;
        [theMapView setCenterCoordinate:appDelegate.locationManager.location.coordinate zoomLevel:14 animated:YES];
    }
}

-(void) mapView:(MKMapView *)mapView regionWillChangeAnimated:(BOOL)animated
{
    if( isTracking && ! pendingRegionChange )
    {
        isTracking = NO;
    }

    pendingRegionChange = NO;
}

@end

已解决viewcontroller.m中以下代码的问题：

- (void)viewDidDisappear:(BOOL)animated{
    [timer invalidate];
}