Swift

Question

我的 mapView 有一个自定义注释。我最初用一些数据在上面设置了坐标、标题（例如"first title"）、副标题（例如"first address"）、userId 和距离（例如0 米）属性。我将它添加到 mapView 和数组以供以后使用。一切正常，它显示在 mapView 上，我按下它，标注显示初始数据。

我后来得知该标注的位置已更改。我遍历数组并使用坐标、标题（例如 "new title"）、副标题（例如 "new address"）和距离（例如 100 米）属性的新数据更新标注。我还将标注从它的原始位置动画化到它的新位置。动画效果很好，标注从 A 点移动到 B 点。

问题是当我点击注释时，标注上显示的是旧数据而不是新数据。

我用calloutAccessoryControlTapped推一个新的vc。当我在那里放置一个断点时，自定义引脚具有所有新数据。错误似乎与标注有关。

我该如何解决这个问题？

我不想清除 mapView 中的所有注释，所以这不是一个选项。我调用 mapView.removeAnnotation(customPin) 和 mapView.addAnnotation(customPin) 来解决该图钉的问题，但是当图钉被移除并添加回地图时会闪烁，然后当它动画到它的新位置时它看起来不稳定。

自定义注释

class CustomPin: NSObject, MKAnnotation {

    @objc dynamic var coordinate: CLLocationCoordinate2D
    var title: String?
    var subtitle: String?
    var userId: String?
    var distance: CLLocationDistance?

    init(coordinate: CLLocationCoordinate2D, title: String, subtitle: String, userId: String, distance: CLLocationDistance?) {

        self.coordinate = coordinate
        self.title = title
        self.subtitle = subtitle
        self.userId = userId
        self.distance = distance

        super.init()
    }
}

第一次使用初始数据设置注释

firstFunctionThatGetsTheInitialLocation(origLat, origLon) {

   let firstCoordinate = CLLocationCoordinate2DMake(origLat, origLon)   

   let distanceInMeters: CLLocationDistance = self.center.distance(from: anotherUsersLocation)

   let customPin = CustomPin(coordinate: firstCoordinate, title: "first title", subtitle: "first address", userId: "12345", distance: distance)

    DispatchQueue.main.async { [weak self] in

      self?.mapView.addAnnotation(customPin)

      self?.arrOfPins.append(customPin)
    }
}

第二次使用新数据设置注释

secondFunctionThatGetsTheNewLocation(newCoordinate: CLLocationCoordinate2D, newDistance: CLLocationDistance) {

    for pin in customPins {

        pin.title = "second title" // ** updates but the callout doesn't reflect it
        pin.subTitle = "second address" // ** updates but the callout doesn't reflect it
        pin.distance = newDistance // ** updates but the callout doesn't reflect it

       // calling these gives me the new data but the annotation blinks and moves really fast to it's new location
       // mapView.removeAnnotation(pin)
       // mapView.addAnnotation(pin)

        UIView.animate(withDuration: 1) {
            pin.coordinate = newCoordinate // this updates and animates to the new location with no problem
        }
    }
}

MapView viewFor annotation

func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {

    if annotation.isKind(of: MKUserLocation.self) { return nil }

    guard let annotation = annotation as? CustomPin else { return nil }

    let reuseIdentifier = "CustomPin"

    var annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: reuseIdentifier)

    if annotationView == nil {
        annotationView = MKAnnotationView(annotation: annotation, reuseIdentifier: reuseIdentifier)
        annotationView?.canShowCallout = true
        annotationView?.calloutOffset = CGPoint(x: -5, y: 5)

        annotationView?.rightCalloutAccessoryView = UIButton(type: .detailDisclosure)

        annotationView?.image = UIImage(named: "chevronImage")

    } else {
        annotationView?.annotation = annotation
    }

    annotationView?.detailCalloutAccessoryView = nil
    annotationView?.detailCalloutAccessoryView = createCallOutWithDataFrom(customPin: annotation)

    return annotationView
}

为标注创建 UIView

func createCallOutWithDataFrom(customPin: CustomPin) -> UIView {

    let titleText = customPin.title
    let subTitleText = customPin.subTitle
    let distanceText = subTitle.distance // gets converted to a string

    // 1. create a UIView
    // 2. create some labels and add the text from the title, subTitle, and distance and add them as subViews to the UIView
    // 3. return the UIView
}

Answer 1

有几个问题：

您需要对要观察的任何属性使用 @objc dynamic 限定符。标准标注在 title 和 subtitle 上执行 Key-Value Observation (KVO)。（注释视图观察到 coordinate 的变化。）

如果你想观察userid和distance，你也必须制作那些@objc dynamic。请注意，您必须使 distance 成为 non-optional 才能使其可观察：

var distance: CLLocationDistance

所以：

class CustomAnnotation: NSObject, MKAnnotation {
    // standard MKAnnotation properties

    @objc dynamic var coordinate: CLLocationCoordinate2D
    @objc dynamic var title: String?
    @objc dynamic var subtitle: String?

    // additional custom properties

    @objc dynamic var userId: String
    @objc dynamic var distance: CLLocationDistance

    init(coordinate: CLLocationCoordinate2D, title: String, subtitle: String, userId: String, distance: CLLocationDistance) {
        self.userId = userId
        self.distance = distance
        self.coordinate = coordinate
        self.title = title
        self.subtitle = subtitle

        super.init()
    }
}

就像我说的，标准标注观察 title 和 subtitle。虽然您必须使注释属性可观察，但如果您要构建自己的 detailCalloutAccessoryView，则必须执行自己的 KVO：

class CustomAnnotationView: MKMarkerAnnotationView {
    private let customClusteringIdentifier = "..."

    override init(annotation: MKAnnotation?, reuseIdentifier: String?) {
        super.init(annotation: annotation, reuseIdentifier: reuseIdentifier)
        canShowCallout = true
        detailCalloutAccessoryView = createCallOutWithDataFrom(customAnnotation: annotation as? CustomAnnotation)
        clusteringIdentifier = customClusteringIdentifier
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    deinit {
        removeAnyObservers()
    }

    override var annotation: MKAnnotation? {
        didSet {
            removeAnyObservers()
            clusteringIdentifier = customClusteringIdentifier
            if let customAnnotation = annotation as? CustomAnnotation {
                updateAndAddObservers(for: customAnnotation)
            }
        }
    }

    private var subtitleObserver: NSKeyValueObservation?
    private var userObserver: NSKeyValueObservation?
    private var distanceObserver: NSKeyValueObservation?

    private let subtitleLabel: UILabel = {
        let label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        return label
    }()

    private let userLabel: UILabel = {
        let label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        return label
    }()

    private let distanceLabel: UILabel = {
        let label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        return label
    }()
}

private extension CustomAnnotationView {
    func updateAndAddObservers(for customAnnotation: CustomAnnotation) {
        subtitleLabel.text = customAnnotation.subtitle
        subtitleObserver = customAnnotation.observe(\.subtitle) { [weak self] customAnnotation, _ in
            self?.subtitleLabel.text = customAnnotation.subtitle
        }

        userLabel.text = customAnnotation.userId
        userObserver = customAnnotation.observe(\.userId) { [weak self] customAnnotation, _ in
            self?.userLabel.text = customAnnotation.userId
        }

        distanceLabel.text = "\(customAnnotation.distance) meters"
        distanceObserver = customAnnotation.observe(\.distance) { [weak self] customAnnotation, _ in
            self?.distanceLabel.text = "\(customAnnotation.distance) meters"
        }
    }

    func removeAnyObservers() {
        subtitleObserver = nil
        userObserver = nil
        distanceObserver = nil
    }

    func createCallOutWithDataFrom(customAnnotation: CustomAnnotation?) -> UIView {
        let view = UIView()
        view.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(subtitleLabel)
        view.addSubview(userLabel)
        view.addSubview(distanceLabel)

        NSLayoutConstraint.activate([
            subtitleLabel.topAnchor.constraint(equalTo: view.topAnchor),
            subtitleLabel.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            subtitleLabel.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            subtitleLabel.bottomAnchor.constraint(equalTo: userLabel.topAnchor),

            userLabel.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            userLabel.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            userLabel.bottomAnchor.constraint(equalTo: distanceLabel.topAnchor),

            distanceLabel.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            distanceLabel.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            distanceLabel.bottomAnchor.constraint(equalTo: view.bottomAnchor)
        ])

        if let customAnnotation = customAnnotation {
            updateAndAddObservers(for: customAnnotation)
        }

        return view
    }
}

结果是：

Swift - 如何在自定义 MKAnnotation 标注中更新数据？

Swift -How to Update Data in Custom MKAnnotation Callout?

ios

mkannotation

calloutview