在背景中比较来自 2 个位置的 2 个城市

Question

我有一个应用程序，用户可以保存位置并设置要通知的半径：1KM、5KM（如果他之前保存的位置和他当前的位置在设置的半径内，用户将收到通知) 和 "City" （如果之前保存的位置所在的城市与当前所在的城市是同一个城市，用户将收到通知）。

注意：我正在使用 Google Maps iOS SDK。

我有一个名为 -sendNotificationIfNeeded 的方法，用于检查是否发送通知，代码：

-(void)sendNotificationIfNeeded
{    
    if (self.muteEnabled==YES) { //Check if the user muted the app
        NSLog(@"Mute enabled");
        return;
    }

    //Important part:
    if([self checkIfUserInRadiusForLocation:[self.savedLocations objectAtIndex:0]])
    {
        UILocalNotification *notification=[self createNotification];
        [self sendNotification:notification];
    }
}

方法checkIfUserInRadiusForLocation检查savedLocation（CLCircularRegion）的半径并检查用户是否在这个半径内，代码：

-(BOOL)checkIfUserInRadiusForLocation:(SavedLocation*)location
{
    if(location.radiusString isEqualToString:@“1KM”)
    {
        if(location.circularRegion containsCoordinate:self.locationManager.location.coordinate)
        {
            return YES;
        }
    }else if(location.radiusString isEqualToString:@“5KM”)
    {
        if(location.circularRegion containsCoordinate:self.locationManager.location.coordinate)
        {
            return YES;
        }
    //Important part:
    }else if(location.radiusString isEqualToString:@“City”)
    {
        if([self checkIfUserCityIsSameToLocation:location)
        {
            return YES;
        }
    }
    return NO;
}

方法checkIfUserCityIsSameToLocation:找到savedLocation城市和用户所在城市并检查它们是否相等（问题出在这里），代码：

-(BOOL)checkIfUserCityIsSameToLocation:(savedLocation*)location
{
    //Checking user's city
    __block NSString *userCity;
    [[GMSGeocoder geocoder]reverseGeocodeCoordinate:self.locationManager.location.coordinate completionHandler:^(GMSReverseGeocodeResponse *response, NSError *error) {
        if (error) {
            NSLog(@"%@",[error description]);
        }
        userCity=[[[response results] firstObject] locality];
    }];
    //Checking savedLocation’s city
    __block NSString *savedLocationCity;
    [[GMSGeocoder geocoder]reverseGeocodeCoordinate:location.circularRegion.center completionHandler:^(GMSReverseGeocodeResponse *response, NSError *error) {
        if (error) {
            NSLog(@"%@",[error description]);
        }
        savedLocationCity=[[[response results] firstObject] locality];

        NSLog(@"");
    }];

    if ([userCity isEqualToString:savedLocationCity]) { //Both string cities are nil
        Return YES;
    }else
    {
        Return No
    }
}

问题是，当应用程序到达 checkIfUserCityIsSameToLocation: 上的 if 语句时，userCity 和 savedLocationCity 都为零（因为 reverseGeocodeCoordinate: completionHandler: 方法是运行在后台线程上）。

我想不出怎么解决，

如果有人能帮助我，我将非常感激。

非常感谢！

Answer 1

这样做：

-(BOOL)checkIfUserInRadiusForLocation:(SavedLocation*)location userCity: (NSString *) userCity locationCity: (NSString *) locationCity
{
    if(location.radiusString isEqualToString:@“1KM”)
    {
      if(location.circularRegion containsCoordinate:self.locationManager.location.coordinate)
      {
        return YES;
      }
    }else if(location.radiusString isEqualToString:@“5KM”)
    {
      if(location.circularRegion containsCoordinate:self.locationManager.location.coordinate)
      {
        return YES;
      }
    //Important part:
    }else if(location.radiusString isEqualToString:@“City”)
    {
      if([userCity isEqual: locationCity])
      {
        return YES;
      }
    }
return NO;
}


-(void)sendNotificationIfNeeded
{    
    if (self.muteEnabled==YES) { //Check if the user muted the app
        NSLog(@"Mute enabled");
        return;
    }
    SavedLocation* location = [self.savedLocations objectAtIndex:0];
    [[GMSGeocoder geocoder]reverseGeocodeCoordinate:self.locationManager.location.coordinate completionHandler:^(GMSReverseGeocodeResponse *response, NSError *error) {
    if (error) {
        NSLog(@"%@",[error description]);
    }
    NSString *userCity=[[[response results] firstObject] locality];
   [[GMSGeocoder geocoder]reverseGeocodeCoordinate:location.circularRegion.center completionHandler:^(GMSReverseGeocodeResponse *response, NSError *error) {
    if (error) {
        NSLog(@"%@",[error description]);
    }
    NSString *savedLocationCity=[[[response results] firstObject] locality];

    if([self checkIfUserInRadiusForLocation:location userCity: userCity locationCity: savedLocationCity])
    {
      UILocalNotification *notification=[self createNotification];
      [self sendNotification:notification];
    }
    }];
  }];
}

在背景中比较来自 2 个位置的 2 个城市

Comparing 2 cities from 2 locations in background

iphone

cocoa-touch

objective-c

ios

google-maps-sdk-ios