ios - Swift 将数据从 subview 发送到父 View Controller

Question

我正在开发一个有 View Controller 和 subview 的应用程序。在 subview 上，我正在加载 Google map ，在主视图上，我有一个标签。

我的问题是如何将数据从 subview ( map 地理位置)传递到主视图上的标签，并在使用 Swift 更新位置时更新它。

我找到的所有教程都使用 prepareForSegue，我想在其中自动更新标签，因为它在主视图上。

谢谢

更新:我似乎无法让委托(delegate)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(delegate)模式是你的 friend 。

在父 View Controller 将实现的 subview Controller 上声明一个协议(protocol)。无论何时，都可以在 subview Controller 中的委托(delegate)引用上调用一个方法 - 这将使用子 VC 中的数据更新父 View Controller 。

这个 SO 问题巧妙地解释了子父委托(delegate) How do I set up a simple delegate to communicate between two view controllers?