试图在MKMapView中查找用户位置的问题

我在尝试让用户的当前位置显示在MKMapView上时遇到问题。 这是相关的代码：

标题：

// ParkingMapViewController.m #import  #import  @interface ParkingMapViewController : UIViewController  { MKMapView *mapView; CLLocationManager *locationManager; } @property (nonatomic, retain) IBOutlet MKMapView *mapView; @property (nonatomic, retain) CLLocationManager *locationManager; -(void)loadAnnotations; -(void)showCurrentLocationButtonTapped:(id)sender; @end 

实施（部分）：

 // ParkingMapViewController.m - (void)viewDidLoad { [super viewDidLoad]; self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:100 target:self action:@selector(showCurrentLocationButtonTapped:)]; [self loadAnnotations]; CLLocationCoordinate2D centerCoord = { UCD_LATITUDE, UCD_LONGITUDE }; [mapView setCenterCoordinate:centerCoord zoomLevel:13 animated:NO]; //from "MKMapView+ZoomLevel.h" } - (void)showCurrentLocationButtonTapped:(id)sender { NSLog(@"Showing current location."); //[self.mapView setShowsUserLocation:YES]; //mapView.showsUserLocation = YES; //[sender setEnabled:NO]; //TODO: Uncomment and test locationManager = [[CLLocationManager alloc] init]; locationManager.delegate = self; locationManager.distanceFilter = kCLDistanceFilterNone; // whenever we move locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters; // 100 m [locationManager startUpdatingLocation]; } - (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation { [mapView setCenterCoordinate:newLocation.coordinate]; if ([mapView showsUserLocation] == NO) { [mapView setShowsUserLocation:YES];//when this line is commented, there is no problem } [mapView setCenterCoordinate:newLocation.coordinate zoomLevel:13 animated:YES]; } - (void)viewDidUnload { [super viewDidUnload]; [mapView setShowsUserLocation:NO]; } - (void)dealloc { [locationManager release]; [mapView release]; [super dealloc]; } 

运行应用程序时，地图视图会显示注释和所有内容，但是当按下当前位置按钮时，地图会重新定位到其新位置（轻微移动），稍后会发生崩溃。 当我注释掉[mapView setShowsUserLocation:YES]; 没有问题，但否则它会在控制台中吐出这个错误：

 2010-11-30 22:57:20.657 Parking[53430:207] -[MKUserLocation annotationType]: unrecognized selector sent to instance 0x78427f0 2010-11-30 22:57:20.659 Parking[53430:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[MKUserLocation annotationType]: unrecognized selector sent to instance 0x78427f0' *** Call stack at first throw: ( 0 CoreFoundation 0x0266ab99 __exceptionPreprocess + 185 1 libobjc.A.dylib 0x027ba40e objc_exception_throw + 47 2 CoreFoundation 0x0266c6ab -[NSObject(NSObject) doesNotRecognizeSelector:] + 187 3 CoreFoundation 0x025dc2b6 ___forwarding___ + 966 4 CoreFoundation 0x025dbe72 _CF_forwarding_prep_0 + 50 5 Parking 0x00003ddb -[ParkingMapViewController mapView:viewForAnnotation:] + 64 6 MapKit 0x023a8130 -[MKAnnotationContainerView _addViewForAnnotation:] + 175 7 MapKit 0x023a2b2a -[MKAnnotationContainerView _addViewsForAnnotations:animated:] + 251 8 MapKit 0x0239e657 -[MKAnnotationContainerView showAddedAnnotationsAnimated:] + 137 9 MapKit 0x0237837c -[MKMapView _showAddedAnnotationsAndRouteAnimated:] + 102 10 MapKit 0x02376a88 -[MKMapViewInternal delayedShowAddedAnnotationsAnimated] + 191 11 Foundation 0x000571c9 __NSFireTimer + 125 12 CoreFoundation 0x0264bf73 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 19 13 CoreFoundation 0x0264d5b4 __CFRunLoopDoTimer + 1364 14 CoreFoundation 0x025a9dd9 __CFRunLoopRun + 1817 15 CoreFoundation 0x025a9350 CFRunLoopRunSpecific + 208 16 CoreFoundation 0x025a9271 CFRunLoopRunInMode + 97 17 GraphicsServices 0x02f4900c GSEventRunModal + 217 18 GraphicsServices 0x02f490d1 GSEventRun + 115 19 UIKit 0x002cfaf2 UIApplicationMain + 1160 20 Parking 0x000020e0 main + 102 21 Parking 0x00002071 start + 53 ) terminate called after throwing an instance of 'NSException' 

谷歌搜索表明这很可能是一个IB问题但我无法发现它。 这是我在IB中设置的屏幕：

任何帮助都将非常感激。 谢谢！

Answer 1

问题看起来像是在viewForAnnotation方法中。 代码试图在MKUserLocation annotation annotationType上调用annotationType （它没有这样的方法）。

在viewForAnnotation ，它应检查请求view的注释类型并进行相应处理。

但是，如果您使用的是MKMapView ，则无需使用CLLocationManager来获取用户的current location 。 只需将showsUserLocation设置为YES ， map view显示用户所在的蓝点。

在任何一种情况下， viewForAnnotation方法都需要首先检查annotation class类型。 像这样的东西应该在顶部：

 - (MKAnnotationView *) mapView:(MKMapView *)mapView viewForAnnotation:(id ) annotation { if ([annotation isKindOfClass:MKUserLocation.class]) { //it's the built-in user location annotation, return nil to get default blue dot... return nil; } //handle your custom annotations... }