CLLocationManager 没有获取位置

Question

我正在使用 CLLocationManager 获取设备的当前位置，并尝试获取 location 属性以获取经度和纬度，如下所示：

-(void)getCurrentLocation{
CLLocationManager *manager=[[CLLocationManager alloc]init];;
manager.delegate=self;
manager.desiredAccuracy=kCLLocationAccuracyBest;
self.currentLocation=manager.location;
NSLog(@"Current Lat :%f",self.currentLocation.coordinate.latitude);
NSLog(@"Current Long :%f",self.currentLocation.coordinate.longitude);

[manager startUpdatingLocation];
}

鉴于：

self.currentLocation is a property inside my class (Which is the CLLocationManagerDelegate) as follows:

.h

@property(nonatomic,strong) CLLocation *currentLocation;

.m中的getter如下：

-(CLLocation *)currentLocation{
if (!_currentLocation) {
    _currentLocation=[[CLLocation alloc]init ];
}
return _currentLocation;

}

忘了说我实现了didUpdateToLocation方法如下：

-(void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
      fromLocation:(CLLocation *)oldLocation {
NSLog(@"didUpdateToLocation");
CLLocation *loc=newLocation;
if (loc!=nil) {
    self.currentLocation=loc;

}  

}

我也尝试在startUpdateLocation 调用之后将此声明：

    self.currentLocation=manager.location;

问题是，当我调用前面的函数 getCurrentLocation 时，它里面的两个 NSLog 会打印 0.000000，这意味着 manager.location 不起作用，奇怪的是 didUpdateToLocation 里面的第一个 NSLog 没有t打印，提前谢谢

Answer 1

您不能只从 CLLocationManager 中读取位置。它需要在分配该属性之前更新其位置：

The value of this property is nil if no location data has ever been retrieved.

CLLocationManager SDK

你必须实现委托方法locationManager:didUpdateLocations:

当它被调用时，您可以读取location 属性，或查看locations 参数：

- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations {
    self.currentLocation = [locations firstObject];

    NSLog(@"Current Lat :%f",self.currentLocation.coordinate.latitude);
    NSLog(@"Current Long :%f",self.currentLocation.coordinate.longitude);

    [manager stopUpdatingLocation]
}

您可以在接到第一个电话时拨打[manager stopUpdatingLocation]，因此它不会继续运行。