位置管理器提供空坐标 [英] location manager giving null coordinates

问题描述

以下代码导致空坐标。奇怪的是，UIAlert提示应用程序使用当前位置会在用户选择是之前短暂出现。

The following code results in null coordinates. The weird thing is the UIAlert prompting the app to use current location appears briefly before the user can select yes.

我使用的我的代码：

CLLocationManager *locationManager;
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
[locationManager startUpdatingLocation];
locationManager = [[CLLocationManager alloc] init];
locationManager.distanceFilter = kCLDistanceFilterNone;
locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters;
[locationManager startUpdatingLocation];
float latitude = locationManager.location.coordinate.latitude;
float longitude = locationManager.location.coordinate.longitude;
NSLog(@"%.8f",latitude);
NSLog(@"%.8f",longitude);

NSLog为两个坐标打印 0.0000000 。

The NSLog prints 0.0000000 for both coordinates.

谢谢！

推荐答案

获得0的原因是因为位置管理器当时尚未收集任何数据（它已经开始考虑）

The reason you're getting 0 is because the location manager hasn't collected any data at that point (it has started thought)

您需要将您的课程设置为位置管理器的委托（即提供

You need to set your class as the delegate of the location manager (ie supplying a function that is called whenever a new location is retrieved), and also retain your location manager.

// Inside .m file

@interface MyClass () <CLLocationManagerDelegate> // Declare this class to implement protocol CLLocationManagerDelegate

@property (strong, nonatomic) CLLocationManager* locationManager; // Retains it with strong keyword

@end

@implementation MyClass

// Inside some method

   self.locationManager = [[CLLocationManager alloc] init];
   self.locationManager.delegate = self;
   self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
   self.locationManager.distanceFilter = kCLDistanceFilterNone;
   [self.locationManager startUpdatingLocation];

// Delegate method
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations {
    CLLocation* loc = [locations lastObject]; // locations is guaranteed to have at least one object
    float latitude = loc.coordinate.latitude;
    float longitude = loc.coordinate.longitude;
    NSLog(@"%.8f",latitude);
    NSLog(@"%.8f",longitude);
}

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