如何让CLLLocationManager立即返回一个位置？

Question

我想调整我的CLLocationManager设置，以便在我调用startUpdatingLocation时立即调用委托。任何想法如何做到这一点？

Answer 1

那是不可能的。原因很简单，该设备没有定位，可以随时匹配您所需的精度。它可能不得不打开GPS芯片来做到这一点，这也需要一些时间来创建一个位置（没有额外的信息和过时的年历，在最坏的情况下这可能需要长达15分钟）。

Answer 2

以这种方式调整CLLocationManger是不可能的。然而，你可以做的是围绕CLLocationManager编写一个包装器，它在启动时获得当前位置，并在你每次请求时返回它。但是，可能存在位置尚未（可用）的情况，并且随着您始终使用GPS设备，此方法非常耗电。

Answer 3

这是到目前为止还没有在最佳方式（甚至不是一个很好的大概样子）使用CLLocationManager，当我发现我上回去和改变我的代码只有一个CLLocationManager内规划的时候我AppDelegate并让所有的子视图控制器调用AppDelegate以获取其位置需求。

我在视图控制器（不是主控制器或应用程序委托）中有以下代码，并且在视图控制器被我的主视图导航控制器按下后约5-10秒，它开始用NSLog精准的长/纬度我的位置（即委托locationManager:didUpdateToLocation:fromLocation:开始被称为法）：

- (void)viewDidLoad { 
    [super viewDidLoad]; 
    // .... 
    self.locationManager = [[[CLLocationManager alloc] init] autorelease]; 
    [locationManager setDelegate:self]; 
    [locationManager setDesiredAccuracy:kCLLocationAccuracyBest]; 
    [locationManager setDistanceFilter:kCLDistanceFilterNone]; 
    [locationManager startUpdatingLocation]; 
    // .... 
} 

// This will be called just a few seconds after the view appears and the 
// location is accurate (if I have location services on and good sky-line of sight) 
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation { 
    NSDate* eventDate = newLocation.timestamp; 
    NSTimeInterval howRecent = [eventDate timeIntervalSinceNow]; 
    if (abs(howRecent) < 5.0) { 
     self.latitude = [NSNumber numberWithDouble:newLocation.coordinate.latitude]; 
     self.longitude = [NSNumber numberWithDouble:newLocation.coordinate.longitude]; 
     NSLog(@"New Latitude %+.6f, Longitude %+.6f", newLocation.coordinate.latitude, newLocation.coordinate.longitude); 
    } 
} 

// Then, tear down the location Manager (so I can use it in another view controller) 
// A bit excessive possibly, but I like to be absolutely sure that my App does not use the GPS 
// when it doesn't need it to save batter life. 
- (void)viewWillDisappear:(BOOL)animated { 
    [super viewWillDisappear:animated]; 
    [locationManager stopMonitoringSignificantLocationChanges]; 
    [locationManager stopUpdatingHeading]; 
    [locationManager stopUpdatingLocation]; 
} 

- (void)viewDidDisappear:(BOOL)animated { 
    [super viewDidDisappear:animated]; 
    [locationManager stopMonitoringSignificantLocationChanges]; 
    [locationManager stopUpdatingHeading]; 
    [locationManager stopUpdatingLocation]; 
} 

- (void)viewDidUnload { 
    [locationManager stopUpdatingLocation]; 
    [locationManager stopMonitoringSignificantLocationChanges]; 
    [locationManager stopUpdatingHeading]; 
    [locationManager setDelegate:nil]; 
    self.locationManager = nil; 
} 

- (void)dealloc { 
    // .... 
    [locationManager stopUpdatingLocation]; 
    [locationManager setDelegate:nil]; 
    [locationManager release], locationManager = nil; 
    // .... 
    [super dealloc]; 
} 

然后，像actionSheet:clickedButtonAtIndex:的地方，我能得到的位置值on0demand与locationManager.location.coordinate.latitude/locationManager.location.coordinate.longitude或self.latitude/self.longitude。