如何在iOS中将数据从容器发送到父视图控制器？

参见英文答案 > Passing Data between View Controllers41个
我正在尝试将数据从容器(子视图)发送到父级.在另一个视图控制器中,我能够使用从父级向子级发送数据

-(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender

但是,我不确定如何将数据从子节点发送到父节点,特别是我正在尝试将属性userLat(它是容器的属性)发送给父节点.有什么建议？

PinViewController.m(父)：

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.


    NSLog(@"children : %@",self.childViewControllers);
//this returns the child view controller 

NSLog(@"children : %@",self.childViewControllers.userLat);
//userLat is a property of the child view controller,but displays an error in Xcode.

}

MapWithinPinViewController(子,容器)

- (void)viewDidLoad
{


    GMSCameraPosition *camera = [GMSCameraPosition cameraWithLatitude:-33.86 longitude:151.20 zoom:6];
    mapView_ = [GMSMapView mapWithFrame:CGRectZero camera:camera];
    mapView_.myLocationEnabled = YES;
    mapView_.delegate = self;
    self.view = mapView_;

}


 - (void)mapView:(GMSMapView *)mapView didTapAtCoordinate:(CLLocationCoordinate2D)coordinate {
    NSLog(@"You tapped at %f,%f",coordinate.latitude,coordinate.longitude);

    [mapView_ clear];

    GMSMarker *marker = [[GMSMarker alloc] init];
    marker.position = CLLocationCoordinate2DMake(coordinate.latitude,coordinate.longitude);

    self.userLat = @"test";

    marker.map = mapView_;

}