在重新加载地图时，带注释的引脚不会被加载

我在我的应用程序中使用苹果地图来实现maps.I使用下面的代码。

我的问题是，它只显示第一次加载时的引脚。

我已经写了这样的代码

- (void)viewDidLoad { [super viewDidLoad]; self.title = @"Locate Engineer"; [worldView setMapType:MKMapTypeStandard]; [worldView setShowsUserLocation:YES]; worldView.delegate = self; } - (void)viewDidUnload { [super viewDidUnload]; } -(id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; if(self) { i=0; locationManager = [[CLLocationManager alloc]init]; [locationManager setDelegate:self]; [locationManager setDesiredAccuracy:kCLLocationAccuracyBest]; [locationManager startUpdatingLocation]; } return self; } -(void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; [locationManager startUpdatingLocation]; } -(void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation { NSLog(@"%@",newLocation); } -(MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation { pinView = nil; if(annotation != mapView.userLocation) { NSString * defaultPinID = @"aa"; //removed autorelease from the code below by coder pinView = (MKPinAnnotationView *) [worldView dequeueReusableAnnotationViewWithIdentifier:defaultPinID]; if(pinView == nil) { pinView .tag =i; pinView = [[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:defaultPinID] ; //pinView.image = [UIImage imageNamed:@"serviceengineer.png"]; NSLog(@"pnID is %d",i); NSLog(@"value of i is %d",i); if ([[pinView.annotation title] isEqualToString:@"Levitton"]) { pinView.pinColor = MKPinAnnotationColorRed; pinView.canShowCallout = YES; pinView.draggable = NO; } else { pinView.pinColor = MKPinAnnotationColorGreen; UIButton *rightButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure]; [rightButton addTarget:self action:@selector(mapAction:) forControlEvents:UIControlEventTouchUpInside]; rightButton.tag =i; pinView.rightCalloutAccessoryView = rightButton; // pinView.animatesDrop = YES; pinView.canShowCallout = YES; pinView.draggable = NO; } } else { [worldView.userLocation setTitle:@"Title here"]; } i++; } return pinView; } -(void)mapView:(MKMapView *)mapView didUpdateUserLocation:(MKUserLocation *)userLocation { ServiceEngineersList *engList = [ServiceEngineers findAll]; MKCoordinateSpan spans; spans.latitudeDelta = 0.5; spans.longitudeDelta = 0.5; ServiceEngineers *obj1= [engList objectAtIndex:0]; // location1.latitude = 40.728224000000; //location1.longitude =-73.794852000000; location1.latitude = [obj1.LATITUDE doubleValue]; location1.longitude =[obj1.LONGITUDE doubleValue]; ad1 = [[annotationTest alloc] init]; ad1.pinColor = MKPinAnnotationColorGreen; MKCoordinateRegion regions = MKCoordinateRegionMakeWithDistance(location1, 250,250); regions.span = spans; [worldView setRegion:regions animated:YES]; [worldView setZoomEnabled:YES]; [worldView addAnnotation:ad1]; ServiceEngineers *obj2= [engList objectAtIndex:1]; ad2 = [[annotationTest2 alloc] init]; ad2.pinColor = MKPinAnnotationColorGreen; //location2.latitude = 40.710841000000; //location2.longitude=-73.897769000000; location2.latitude = [obj2.LATITUDE doubleValue]; location2.longitude =[obj2.LONGITUDE doubleValue]; MKCoordinateRegion region1 = MKCoordinateRegionMakeWithDistance(location2, 250, 250); region1.span = spans; [worldView setRegion:region1 animated:YES]; [worldView setZoomEnabled:YES]; [worldView addAnnotation:ad2]; ServiceEngineers *obj3= [engList objectAtIndex:2]; ad3 = [[annotationTest3 alloc] init]; ad3.pinColor = MKPinAnnotationColorGreen; //location3.latitude = 40.726768000000; //location3.longitude=-73.634295000000; location3.latitude = [obj3.LATITUDE doubleValue]; location3.longitude =[obj3.LONGITUDE doubleValue]; MKCoordinateRegion region2 = MKCoordinateRegionMakeWithDistance(location3, 250, 250); region2.span = spans; [worldView setRegion:region2 animated:YES]; [worldView setZoomEnabled:YES]; [worldView addAnnotation:ad3]; ServiceEngineers *obj4= [engList objectAtIndex:3]; ad4 = [[annotationTest4 alloc] init]; ad4.pinColor = MKPinAnnotationColorGreen; //location4.latitude = 40.702677000000; //location4.longitude=-73.788969000000; location4.latitude = [obj4.LATITUDE doubleValue]; location4.longitude =[obj4.LONGITUDE doubleValue]; MKCoordinateRegion region3 = MKCoordinateRegionMakeWithDistance(location4, 250, 250); region3.span = spans; [worldView setRegion:region3 animated:YES]; [worldView setZoomEnabled:YES]; [worldView addAnnotation:ad4]; ad5 = [[annotationTest5 alloc] init]; ad5.pinColor = MKPinAnnotationColorRed; location5.latitude = 40.7258; location5.longitude= -73.5147; MKCoordinateRegion region4 = MKCoordinateRegionMakeWithDistance(location5, 250, 250); region4.span = spans; [worldView setRegion:region4 animated:YES]; [worldView setZoomEnabled:YES]; [worldView addAnnotation:ad5]; } -(void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error { NSLog(@"Couldnot find location: %@",error); } - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { if(interfaceOrientation == UIInterfaceOrientationLandscapeLeft || interfaceOrientation == UIInterfaceOrientationLandscapeRight) return YES; return NO; } 

请帮我找出问题。我把断点。第二次只是到了

 worldView.delegate = self; 

Answer 1

只需放置在 viewWillAppear 然后在 viewDidLoad 移除即可

 -(void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; locationManager = [[CLLocationManager alloc]init]; [locationManager setDelegate:self]; [locationManager setDesiredAccuracy:kCLLocationAccuracyBest]; [locationManager startUpdatingLocation]; }