ios - Swift 3.0 从不同的 View Controller 获取用户位置坐标

Question

我有两个 View Controller - 一个带有能够通过 locationManager 获取用户位置坐标的 mapView，第二个 VC 我希望能够提取这些用户坐标。

第一个VC:MapView

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    var coordinatesOfUser = locations.last?.coordinate
    print("The value of usercoordinates are \(coordinatesOfUser)")

    // here I want to be able to pull this variable, coordinatesOfUser


    if let location = locations.last {
        let span = MKCoordinateSpanMake(0.00775, 0.00775)
        let myLocation = CLLocationCoordinate2DMake(location.coordinate.latitude,location.coordinate.longitude)
        let region = MKCoordinateRegionMake(myLocation, span)
        map.setRegion(region, animated: true)
    }
    self.map.showsUserLocation = true
    locationManager.stopUpdatingLocation()


}

第二个风投:

我正在考虑在这个 VC 中调用 locationManager 函数。这是将坐标拉到此 VC 的最有效方法吗？如果是这样，我将如何着手去做？

Answer 1

这里有几个选项可以解决这个问题:

委托(delegate):您的第二个 VC 可以有一个委托(delegate)，允许第一个 View Controller 从中获取坐标。这样做的好处是您可以在收到更新时收到。

protocol MyLocationDelegate: class {
    func newLocationArrived(location: CLLocation)
}

class FirstVC: UIViewController, MyLocationDelegate {

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

    func newLocationArrived(location: CLLocation) {
        print(location)
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if let dest = segue.destination as? SecondVC {
            dest.delegate = self
        }
    }
}

class SecondVC: UIViewController, CLLocationManagerDelegate {

    /// ... ...

    weak var delegate: MyLocationDelegate?

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

        /// do something with the location

        /// provide the data via delegation
        delegate?.newLocationArrived(location: CLLocation())
    }
}

通知:通过 NSNotificationCenter 发布通知。也能够在进来时接收更新，只需通过通知中心而不是通过代理发送。

postNotificationName:object:userInfo:

subview Controller :根据第二个 View Controller 及其 View 是否是第一个 View Controller 的 subview ，这可能允许直接访问。并不总是一个选择。

Singleton (CLLocationManager):如果您计划在整个应用程序的其他地方使用位置服务，您可以将 CLLocationManager 移动到它自己的具有 Singleton 的类中。其他 View Controller 可以根据他们的特定需要引用该类。这在使用背景或重大更改位置时也很有用，因为他们可能需要使用 LaunchOptions key 来重新启动位置管理器。

class MyLocationManager: CLLocationManager, CLLocationManagerDelegate {

    static let shared = MyLocationManager()

    var locations = [CLLocation]()

    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        for location in locations {
            self.locations.append(location)
        }
    }
}