MKLocalSearch从外部区域返回结果

Question

我正在搜索地点（如果可能的话，只想展示商家）：

    CLLocationCoordinate2D currentCenter = CLLocationCoordinate2DMake(self.locationManager.location.coordinate.latitude, self.locationManager.location.coordinate.longitude);
MKCoordinateRegion currentRegion = MKCoordinateRegionMakeWithDistance(currentCenter, 15000, 15000);

MKLocalSearchRequest *localSearchRequest = [[MKLocalSearchRequest alloc] init];
localSearchRequest.naturalLanguageQuery = identifier;
[localSearchRequest setRegion:currentRegion];
MKLocalSearch *localSearch = [[MKLocalSearch alloc] initWithRequest:localSearchRequest];
[localSearch startWithCompletionHandler:^(MKLocalSearchResponse *respone, NSError *error) {
    if (!error)
    {
        // Result handling
    }
}];

但结果包括来自其他国家的结果，为什么会这样呢？如果CLLocationManager坐标通过此检查，我只调用此方法：

CLLocationCoordinate2DIsValid

谢谢！