ios - GMSGeoCoder 反向地理编码坐标 : completionHandler: on background thread

Question

我需要从 2 个坐标获取城市名称(我正在使用 GMSGeoCoder -reverseGeocodeCooperative:completionHandler: 方法)，然后对对象进行 comapre。

问题是该方法在后台线程上运行(而不是在主线程中)，当我尝试比较(使用 if 语句)对象时(userCity 和 storeCity - NSString) 仍然是 nil。

我的代码:

//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 store's city
        __block NSString *storeCity;
        [[GMSGeocoder geocoder]reverseGeocodeCoordinate:arounder.radiusCircularRegion.center completionHandler:^(GMSReverseGeocodeResponse *response, NSError *error) {
            if (error) {
                NSLog(@"%@",[error description]);
            }
            arounderCity=[[[response results] firstObject] locality];
        }];
        if ([userCity isEqualToString:arounderCity]) {
            return YES;
        }

有什么想法吗？谢谢!

Answer 1

重构您的代码以在异步任务完成后继续:

这还有一个好处，就是您不会主动等待并阻塞主线程

例如:

- (void)checkCitiesWithCompletionBlock:(void (^)(BOOL same))
    //Checking user's city
    [[GMSGeocoder geocoder]reverseGeocodeCoordinate:self.locationManager.location.coordinate completionHandler:^(GMSReverseGeocodeResponse *response, NSError *error) {
        if (error) {
            NSLog(@"%@",[error description]);
        }
        id userCity=[[[response results] firstObject] locality];

        //Checking store's city
        [[GMSGeocoder geocoder]reverseGeocodeCoordinate:arounder.radiusCircularRegion.center completionHandler:^(GMSReverseGeocodeResponse *response, NSError *error) {
            if (error) {
                NSLog(@"%@",[error description]);
            }
            id arounderCity=[[[response results] firstObject] locality];

            same ([userCity isEqualToString:arounderCity]);
        }];
    }];
}