CLLocation调用委托方法

Question

我试图在切换到特定的视图控制器(FeedVC)时获得用户的位置，这是我目前的代码：

FeedVC.h

#import <CoreLocation/CoreLocation.h>
@interface FeedVC : UIViewController <CLLocationManagerDelegate>

FeedVC.m

@implementation FeedVC
{
    CLLocationManager *locationManager;
    CLLocation *location;
}

- (void)viewDidLoad {
    [super viewDidLoad];

    if (!locationManager)
        locationManager = [[CLLocationManager alloc] init];

    locationManager.delegate = self;
    locationManager.distanceFilter = kCLDistanceFilterNone;
    locationManager.desiredAccuracy = kCLLocationAccuracyKilometer;

    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.0)
        [locationManager requestWhenInUseAuthorization];

    [locationManager startUpdatingLocation];
}

-(void) locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
    NSLog(@"did update locations");

    location = [locations lastObject];
}

- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error
{
    NSLog(@"didFailWithError: %@", error);
}

-(void) viewWillAppear:(BOOL)animated
{
    NSLog(@"%.2f", location.coordinate.latitude);
}

方法locationManager: didUpdateLocations:没有被调用(因为NSLog没有显示)，我在这里跟踪了所有的文档和其他答案，但是我找不到问题的根源，谢谢！

Answer 1

不要在[locationManager startUpdatingLocation];中调用viewDidLoad，在委托方法中调用它：

-(void)locationManager:(CLLocationManager *)manager didChangeAuthorizationStatus:(CLAuthorizationStatus)status{
    if (status == kCLAuthorizationStatusAuthorizedWhenInUse) {
        [locationManager startUpdatingLocation];
    }
}

如果您还没有在plist中添加NSLocationWhenInUseUsageDescription，那么添加它来描述为什么要使用位置服务。