如何讓CLLLocationManager立即返回一個位置？

Question

我想調整我的CLLocationManager設置，以便在我調用startUpdatingLocation時立即調用委託。任何想法如何做到這一點？

Answer 1

那是不可能的。原因很簡單，該設備沒有定位，可以隨時匹配您所需的精度。它可能不得不打開GPS芯片來做到這一點，這也需要一些時間來創建一個位置（沒有額外的信息和過時的年曆，在最壞的情況下這可能需要長達15分鐘）。

Answer 2

以這種方式調整CLLocationManger是不可能的。然而，你可以做的是圍繞CLLocationManager編寫一個包裝器，它在啓動時獲得當前位置，並在你每次請求時返回它。但是，可能存在位置尚未（可用）的情況，並且隨着您始終使用GPS設備，此方法非常耗電。

Answer 3

這是到目前爲止還沒有在最佳方式（甚至不是一個很好的大概樣子）使用CLLocationManager，當我發現我上回去和改變我的代碼只有一個CLLocationManager內規劃的時候我AppDelegate並讓所有的子視圖控制器調用AppDelegate以獲取其位置需求。

我在視圖控制器（不是主控制器或應用程序委託）中有以下代碼，並且在視圖控制器被我的主視圖導航控制器按下後約5-10秒，它開始用NSLog精準的長/緯度我的位置（即委託locationManager:didUpdateToLocation:fromLocation:開始被稱爲法）：

- (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]; 
} 

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