Question

我正在开发iOS应用程序，我想在每次启动app时加载用户的当前位置。

我已在didFinishLaunchingWithOptions中编写了此代码段，但它仅在我启动应用时第一次获取用户位置。（我在5s iOS 7中测试我的应用程序）

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    locationManager = [[CLLocationManager alloc] init];

                locationManager.delegate = self;
                if(IS_OS_8_OR_LATER){
                    NSUInteger code = [CLLocationManager authorizationStatus];
                    if (code == kCLAuthorizationStatusNotDetermined && ([locationManager respondsToSelector:@selector(requestAlwaysAuthorization)] || [locationManager respondsToSelector:@selector(requestWhenInUseAuthorization)])) {
                        // choose one request according to your business.
                        if([[NSBundle mainBundle] objectForInfoDictionaryKey:@"NSLocationAlwaysUsageDescription"]){
                            [locationManager requestAlwaysAuthorization];
                        } else if([[NSBundle mainBundle] objectForInfoDictionaryKey:@"NSLocationWhenInUseUsageDescription"]) {
                            [locationManager  requestWhenInUseAuthorization];
                        } else {
                            NSLog(@"Info.plist does not contain NSLocationAlwaysUsageDescription or NSLocationWhenInUseUsageDescription");
                        }
                    }
                }
                [locationManager startUpdatingLocation];


                 ...
                 ...
                 ...
}

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{

    CLLocation *currentLocation = newLocation;
    [locationManager stopUpdatingLocation];
}

现在，当我回家时，位置发生变化，当我尝试打开我的应用程序时，它不会取回家的位置，而只显示我的旧位置。（我的旧位置与家庭之间存在很大差异位置）

请提供帮助，并提前致谢。

Answer 1

我认为您正在寻找applicationWillEnterForeground或applicationDidBecomeActive，每次用户打开您的应用程序时都会调用它们（＆＃39;变为活动状态＆＃39;）。

didFinishLaunchingWithOptions仅在您的应用程序首次启动时调用一次。

From the docs，概述了州过渡事件：

发布时间：

application:willFinishLaunchingWithOptions

application:didFinishLaunchingWithOptions

转换到前台：

applicationDidBecomeActive

过渡到后台：

applicationDidEnterBackground

转换为非活动状态

applicationWillResignActive（离开前景状态时调用。）

applicationWillEnterForeground（在退出背景状态时调用。）

终止：

applicationWillTerminate（仅在应用程序运行时调用。如果应用程序暂停，则不会调用此方法。）

Answer 2

在 applicationDidBecomeActive 中编写代码。每次来自背景时都会调用它。

- (void)applicationDidBecomeActive:(UIApplication *)application {
//Get Current Location
    if ([CLLocationManager locationServicesEnabled])
    {
        self.locationManager = [[CLLocationManager alloc] init];
        self.locationManager.delegate = self;
        self.locationManager.pausesLocationUpdatesAutomatically = NO;
        self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
        // Check for iOS 8. Without this guard the code will crash with "unknown selector" on iOS 7.
        if ([self.locationManager respondsToSelector:@selector(requestAlwaysAuthorization)]) {
            [self.locationManager requestAlwaysAuthorization];
        }
        [self.locationManager startUpdatingLocation];
    }
    else
    {
        NSLog(@"Location services are not enabled");
    }
}

#pragma mark -- Location Delegate Methods

-(void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
    CLLocation *location = [locations lastObject];
    if (location != nil)    
        NSLog(@"current lat:%f , currentLong:%f",location.coordinate.latitude,location.coordinate.longitude);

    [manager stopUpdatingLocation];
}

- (void)locationManager:(CLLocationManager *)manager
       didFailWithError:(NSError *)error
{
    NSLog(@"Error = %@",error.localizedDescription);
}

-(void)locationManager:(CLLocationManager *)manager didChangeAuthorizationStatus:(CLAuthorizationStatus)status
{
    switch (status) {
        case kCLAuthorizationStatusNotDetermined:
        case kCLAuthorizationStatusRestricted:
        case kCLAuthorizationStatusDenied:
        {
            // do some error handling
        }
            break;
        default:{
            [self.locationManager startUpdatingLocation];
        }
            break;
    }
}

在每次启动app ios时获取当前位置

2 个答案: