如何将UILabel连接到其他类

Question

我在viewcontroller上有一个UI标签，在一个nsobject上有一个字符串（准确度）。我想把字符串放在不断更新的uilabel上，因为当你打印字符串（准确度）时它会更新。有人能帮我吗 ？感谢

class Home: UIViewController {

    @IBOutlet weak var lbl_accuracy: UILabel! 
}

class PBLocation: NSObject, CLLocationManagerDelegate {

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

        if CLLocationManager.locationServicesEnabled() {

            switch(CLLocationManager.authorizationStatus()) {

            case .notDetermined, .restricted, .denied:
                print("No access")

            case .authorizedAlways, .authorizedWhenInUse:

                let accuracy = String(format: "%.4f", (locations.last?.horizontalAccuracy)!)
                print("accuracy = \(accuracy)")
            }
        } else {
            print("Location services are not enabled")
        }
    }
}

Answer 1

您可以使用delegate design pattern将位置准确度发送到Home VC。首先创建LocationUpdatable protocol并添加updateLocationAccuracy(_ accuracy: String) function。在PBLocation类中创建一个弱委托对象，现在您可以通过updateLocationAccuracy方法将精度对象发送到Home VC。最后确认Home VC中的LocationUpdatable协议并实现updateLocationAccuracy(_ accuracy: String)函数，最重要的是将Home VC设置为LocationUpdatable委托对象的委托。

protocol LocationUpdatable: class {
    func updateLocationAccuracy(_ accuracy: String)
}

//Confirm to the LocationUpdatable
class Home: UIViewController, LocationUpdatable {

    @IBOutlet weak var lbl_accuracy: UILabel!

    let location = PBLocation()
    var locationManager: CLLocationManager!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        locationManager = CLLocationManager()
        locationManager.delegate = location
        locationManager.requestAlwaysAuthorization()

        location.delegate = self
    }

    func updateLocationAccuracy(_ accuracy: String) {
        lbl_accuracy.text = accuracy
    }
}

//Create a delegate object
class PBLocation: NSObject, CLLocationManagerDelegate {

    weak var delegate: LocationUpdatable?

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

        if CLLocationManager.locationServicesEnabled() {

            switch(CLLocationManager.authorizationStatus()) {

            case .notDetermined, .restricted, .denied:
                print("No access")

            case .authorizedAlways, .authorizedWhenInUse:

                let accuracy = String(format: "%.4f", (locations.last?.horizontalAccuracy)!)
                print("accuracy = \(accuracy)")
                if let delegate = delegate {
                    delegate.updateLocationAccuracy(accuracy)
                }
            }
        } else {
            print("Location services are not enabled")
        }
    }
}

Answer 2

Introduction to Key-Value Observing Programming Guide

Key-Value Observing

1. NSNotification＆amp; NSNotificationCenter
2. 键值观察
3. 代表
4. 回调

NSNotification＆amp; NSNotificationCenter

// new here
let accuracyNoti = NSNotification.Name(rawValue:"accuracyNoti") 
// end

class PBLocation: NSObject, CLLocationManagerDelegate {

    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        if CLLocationManager.locationServicesEnabled() {
        switch(CLLocationManager.authorizationStatus()) {
            case .notDetermined, .restricted, .denied:
                print("No access")
            case .authorizedAlways, .authorizedWhenInUse:
                let accuracy = String(format: "%.4f", (locations.last?.horizontalAccuracy)!)
                print("accuracy = \(accuracy)")

                // new here
                NotificationCenter.default.post(name: accuracyNoti, object: nil, userInfo: ["accuracy": accuracy)  
                // end
            }
        } else {
            print("Location services are not enabled")
        }
    }
}


class Home: UIViewController {

    @IBOutlet weak var lbl_accuracy: UILabel! 

    // new here
    override func viewDidLoad() {
        super.viewDidLoad()
        NotificationCenter.default.addObserver(self, selector:#selector(didMsgRecv(notification:)),  
                                           name: accuracyNoti, object: nil) 
    }

    deinit {
        NotificationCenter.default.removeObserver(self)
    }

    func didMsgRecv(notification:NSNotification) {
         let userInfo = notification.userInfo as! [String: AnyObject]
         let accuracy = userInfo["accuracy"] as! String 
         lbl_accuracy.text = accuracy      
    } 
    // end
}