showsUserLocation操作附加到按钮不起作用 [英] showsUserLocation action attached to button not working

问题描述

我在应用中遇到地图视图问题。我创建了一个按钮，点击后应该在地图上显示用户位置，但没有任何反应（没有错误信息）。

I am having problems with a map view in my app. I have created a button that when clicked should show users location on the map, but nothing happens (no error messages occur).

我认为问题可能在于我写了代表们。来自相关.h和.m文件的代码如下：

I believe the issue may lie in the way I've written the delegates. The code from the relevant .h and .m files is below:

mapViewController.h

#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>
#import <CoreLocation/CoreLocation.h>
@interface mapViewController : UIViewController  {
MKMapView *mapview;
}
@property (nonatomic, retain) IBOutlet MKMapView *mapview;
-(IBAction)setMap:(id)sender;
-(IBAction)getCurrentLocation:(id)sender;
@property (nonatomic, retain) IBOutlet CLLocationManager *locationManager;
@end

mapViewController.m

#import "mapViewController.h"
@interface mapViewController ()
@end
@implementation mapViewController {
CLLocationManager *locationManager;
}
@synthesize mapview;
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
self.locationManager.delegate=self;
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
self.locationManager.requestWhenInUseAuthorization;
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(IBAction)setMap:(id)sender {
switch (((UISegmentedControl *) sender).selectedSegmentIndex) {
case 0:
    mapview.mapType = MKMapTypeStandard;
    break;
case 1:
    mapview.mapType = MKMapTypeSatellite;
    break;
case 2:
    mapview.mapType = MKMapTypeHybrid;
    break;
   default:
    break;
}
}
-(IBAction)getCurrentLocation:(id)sender {
mapview.showsUserLocation = YES;
}
@end

任何帮助将不胜感激，谢谢

Any help would be greatly appreciated, thanks

推荐答案

您必须实现MapKit委托。 （确保在视图控制器的 .h 中添加委托签名）

You have to implement the MapKit delegates. (Make sure you add the delegate signature in .h of your view controller)

- (void)mapView:(MKMapView *)mapView didUpdateUserLocation:(MKUserLocation *)userLocation {
    MKCoordinateRegion region;
    MKCoordinateSpan span;
    span.latitudeDelta = 0.005;
    span.longitudeDelta = 0.005;
    CLLocationCoordinate2D location;
    location.latitude = userLocation.coordinate.latitude;
    location.longitude = userLocation.coordinate.longitude;
    region.span = span;
    region.center = location;
    [mapView setRegion:region animated:YES];
 }

---

额外： 要处理应用程序是否在前台：

---

Extra: To handle App is on foreground or not:

我们添加2个事件观察者来观察应用程序正在进入后台/返回活动状态：

We add 2 event observers to observe the App is entering background / returning active:

- (void)viewDidLoad{
  [super viewDidLoad];
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(appToBackground) name:UIApplicationDidEnterBackgroundNotification object:nil];
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(appReturnsActive) name:UIApplicationDidBecomeActiveNotification object:nil];
} 

- (void)appToBackground{
  [mapview setShowsUserLocation:NO];
}

- (void)appReturnsActive{
  [mapview setShowsUserLocation:YES];
}

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