xcode 位置管理器给出空坐标
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location manager giving null coordinates
提问by user2402616
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.
以下代码导致空坐标。奇怪的是，在用户选择是之前，提示应用程序使用当前位置的 UIAlert 会短暂出现。
My code which i have used :
我使用过的代码：
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);
The NSLog prints 0.0000000for both coordinates.
NSLog 打印0.0000000两个坐标。
Thanks!
谢谢！
回答by Khanh Nguyen
The reason you're getting 0 is because the location manager hasn't collected any data at that point (it has started thought)
你得到 0 的原因是因为位置管理器当时没有收集任何数据（它已经开始考虑）
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.
您需要将您的类设置为位置管理器的委托（即提供一个在检索新位置时调用的函数），并保留您的位置管理器。
// 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);
}
