Swift将数据从子视图发送到父视图控制器

Question

我正在开发一个应用程序,我有一个视图控制器和子视图.在子视图中我正在加载Google地图,在主视图上我有一个标签.

我的问题是如何将子视图(地图地理位置)中的数据传递到主视图上的标签,并在使用Swift更新位置时更新.

我发现的所有教程都使用prepareForSegue,我想在主视图上自动更新标签.

谢谢

更新:我似乎无法让委托方法工作.代码如下.

MapChildController.swift

import UIKit

protocol ChildViewControllerDelegate{
    func delegateMethod(childViewController:MapChildController, text:String)
}

class MapChildController: UIViewController, CLLocationManagerDelegate {

@IBOutlet weak var mapView: GMSMapView!
let locationManager = CLLocationManager()
var didFindMyLocation = false
var myLocations: [CLLocation] = []

var delegate:ChildViewControllerDelegate?

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    var camera = GMSCameraPosition.cameraWithLatitude(-33.86, longitude: 151.20, zoom: 15, bearing: 0, viewingAngle: 45)
    var mapView = GMSMapView.mapWithFrame(CGRectZero, camera: camera)

    mapView.myLocationEnabled = true
    self.view = mapView

    locationManager.delegate = self
    locationManager.distanceFilter = kCLDistanceFilterNone
    locationManager.desiredAccuracy = kCLLocationAccuracyBest

    if NSProcessInfo().isOperatingSystemAtLeastVersion(NSOperatingSystemVersion(majorVersion: 8, minorVersion: 0, patchVersion: 0)) {
        println("iOS >= 8.0.0")
        locationManager.requestWhenInUseAuthorization()
        //locationManager.requestAlwaysAuthorization()
    }

    mapView.addObserver(self, forKeyPath: "myLocation", options: NSKeyValueObservingOptions.New, context: nil)

    locationManager.startUpdatingLocation()
    //locationManager.startMonitoringSignificantLocationChanges()
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

override func observeValueForKeyPath(keyPath: String, ofObject object: AnyObject, change: [NSObject : AnyObject], context: UnsafeMutablePointer<Void>) {
    if !didFindMyLocation {
        let myLocation: CLLocation = change[NSKeyValueChangeNewKey] as! CLLocation
        var mapView = self.view as! GMSMapView
        mapView.camera = GMSCameraPosition.cameraWithTarget(myLocation.coordinate, zoom: 15.0)
        mapView.settings.myLocationButton = true
        didFindMyLocation = true
    }
}

func locationManager(manager:CLLocationManager, didUpdateLocations locations:[AnyObject]) {

    // println("Last location: \(locations.last)")
    self.delegate?.delegateMethod(self, text: "from child")
}
}

MapController.swift

import Foundation
import UIKit

class MapController : UIViewController, ChildViewControllerDelegate
{
@IBOutlet weak var Label: UILabel!
var LabelText = String()

override func viewDidLoad() {
    super.viewDidLoad()
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

func delegateMethod(controller: MapChildController, text: String) {
    println("The text is " +  text);
}
}

Answer 1

委托模式是您的朋友。

在您的子视图控制器上声明一个将由父视图控制器实现的协议。无论何时需要，都可以在子视图控制器中持有的委托引用上调用方法-这将使用子VC中的数据更新父视图控制器。

这样的问题很好地解释了父级子代委派如何设置一个简单的委托来在两个视图控制器之间进行通信？