Question

我有两个名为myLocality和myCountry的全局NSString变量......

我已将GeoCode设置如下：

    - (void) locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {
    finishedGettingLocation = false;
    if (newLocation.horizontalAccuracy < 200.0f){
        [locationManager stopUpdatingLocation];
        CLGeocoder * geoCoder = [[CLGeocoder alloc] init];
        __block NSString *locality;
        __block NSString *country;
        [geoCoder reverseGeocodeLocation:newLocation completionHandler:^(NSArray *placemarks, NSError *error) {
            for (CLPlacemark * placemark in placemarks) {
                locality = placemark.locality;
                country = placemark.ISOcountryCode;
            }
        }];
        do {

        } while ([geoCoder isGeocoding]);

        myLocality = locality;
        myCountry = country;

        finishedGettingLocation = true;        
    }    
}

我的后台主题如下：

- (void) doWork
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{                   

        finishedGettingLocation = false;

        dispatch_async(dispatch_get_main_queue(), ^{
            locationManager = [[CLLocationManager alloc] init];
            [locationManager setDelegate:self];

            [locationManager setDesiredAccuracy:kCLLocationAccuracyHundredMeters];
            [locationManager startUpdatingLocation];
        });

        int counter = 0;
        do {
            [NSThread sleepForTimeInterval:.1];
            counter ++;
            if (counter % 200 == 0){
                dispatch_async(dispatch_get_main_queue(), ^{
                    Toast *oToast = [Toast toastWithMessage:@"Gps pin-pointing works faster if you are outside"];
                    [oToast showOnView:self.view];
                });
                counter = 0;
            }

        } while (!finishedGettingLocation);

      NSLog(@"%@", myCountry); // this is where I am trying to print
      NSLog(@"%@", myLocality); // this is where I am trying to print

    });
}

（是的，我知道这是非常草率的代码，但是，meh .. xD）

现在，我无法弄清楚当我在其他地方的代码中记录它们时，为什么这些返回null。但是，当我将登录上面的for，即NSLog(@"%@", placemark.locality)我得到正确的值，或者至少我得到一个值。

如何从placemark？

设置全局变量

Answer 1

这些变量在哪里宣布？

如果您在正在进行地理编码的班级中设置了myLocality和myCountry静态，那么其他班级一旦设置就可以访问它们。

另一种方法是创建一个@protocol并让类希望地理编码的结果在完成后接收回调。

Answer 2

在AppDelegate中创建地区和国家/地区属性，并随时随地访问它们。

// Set values
MyAppDelegate *appDelegate = (MyAppDelegate *)[[UIApplication sharedApplication] delegate];

appDelegate.locality = @"Some Area";
appDelegate.country = @"Some Country";


// Get values
MyAppDelegate *appDelegate = (MyAppDelegate *)[[UIApplication sharedApplication] delegate];

NSString *myLocality = appDelegate.locality;
NSString *myCountry = appDelegate.country;

您还可以创建一个专用的单例类，并使用它而不是使用app delegate。

Answer 3

好的，我发现了我的问题。事实证明，我过早地访问变量。我只是将do while循环的条件更改为myCountry == null并且它工作了=]。谢谢你的帮助。

GeoCoding和设置全局变量iOS

3 个答案: