locationManager: didUpdateLocations:代理方法不走

self.currentLoaction = [[CLLocationManager alloc] init];
 [self.currentLoaction setDelegate:self];
self.currentLoaction.desiredAccuracy = kCLLocationAccuracyBest;//精度设定
//_currentLoaction.desiredAccuracy=kCLLocationAccuracyNearestTenMeters;
[ self.currentLoaction startUpdatingLocation];

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

}代理方法不会进去