添加为注释视图子视图的按钮不起作用？

Question

我在地图的didSelect 方法的注释视图中添加了一个子视图，它按预期工作（截图）。我在弹出窗口中有一个按钮，它处于活动状态并启用了用户交互，但我没有收到按钮操作？

我进行了视图调试，似乎该按钮位于视图堆栈的顶部。

func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {
    DispatchQueue.main.async {        
        view.addSubview(self.popupView)
    }
}

这个动作方法在Popupview里面

@IBAction func actionTapPickup(_ sender: UIButton) {
   print("button tapped)
}

Answer 1

您已将您的actionTapPickup 声明为@IBAction。

• 您是否真的从在 Interface Builder 中设计的 NIB 或情节提要中实例化了此视图？如果是这样，请确保您已成功连接您的@IBAction？您是从NIB 实例化此视图（而不是通过编程方式）？

• 另一方面，如果您以编程方式创建此子视图，则不会使用 @IBAction 限定符，而是将其标记为 @objc，然后手动添加 .touchUpInside 事件的目标：

  button.addTarget(self, action: #selector(didTapButton(_:)), for: .touchUpInside)
  

如果您让我们知道您是通过编程方式还是通过 NIB 实例化此自定义弹出/标注，我们可以更详细地概述这一点。 （下面我的示例是程序化实现。）

归根结底，在自定义标注中连接按钮很像在任何地方连接按钮。将@IBAction 用于IB 设计的视图，将@objc 和addTarget 用于以编程方式创建的按钮。

---

顺便说一句，一旦您解决了眼前的问题，值得注意的是，在让自定义标注正常工作方面存在一些微妙的问题。 Location Awareness Programming Guide: Creating Callouts 对此进行了概述，但不幸的是，这些示例是在 Objective-C 中的。无论如何，我们想要的行为是：

• 如果您点击地图上的其他位置（即取消选择注释视图），标注应该会消失；但是
• 如果您点击注释视图的自定义标注（而不是其按钮），您不希望取消选择注释。

为了实现这一点，它在很大程度上可以归结为两个不完全显而易见的小技巧：

1. 为包含命中测试的注释视图添加hitTest。自定义标注。这是为了确保在您点击标注时不会取消选择注释。

2. 在整个标注后面添加一个按钮，以便它消耗任何错过“60 分钟内接听”按钮但仍在标注中的触摸。

因此：

// let’s assume we have an annotation for our pickup location

class PickupLocationAnnotation: MKPointAnnotation {
    let hours: String

    init(hours: String) {
        self.hours = hours
        super.init()
    }
}

// let’s have a protocol for the callout to inform view controller that the “pickup” button was tapped

protocol CalloutViewDelegate: class {
    func calloutTapped(for annotation: MKAnnotation)
}

// Our callout view class

class CalloutView: UIView {
    weak var annotation: MKAnnotation?
    weak var delegate: CalloutViewDelegate?

    let button: UIButton = {
        let button = UIButton(type: .system)
        button.translatesAutoresizingMaskIntoConstraints = false
        button.setTitle("Tap here to pickup in 60 Mins", for: .normal)
        button.addTarget(self, action: #selector(didTapButton(_:)), for: .touchUpInside)
        return button
    }()

    lazy var label: UILabel = {
        let label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        label.numberOfLines = 0
        label.text = (annotation as? PickupLocationAnnotation)?.hours
        return label
    }()

    init(annotation: MKAnnotation?, delegate: CalloutViewDelegate) {
        self.annotation = annotation
        self.delegate = delegate
        super.init(frame: .zero)
        configure()
    }

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

    func configure() {
        addBackgroundButton(to: self)
        addSubview(button)
        addSubview(label)

        NSLayoutConstraint.activate([
            button.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 10),
            button.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -10),
            button.topAnchor.constraint(equalTo: topAnchor, constant: 10),
            button.bottomAnchor.constraint(equalTo: label.topAnchor, constant: -10),

            label.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 10),
            label.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -10),
            label.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -10)
        ])

        layer.cornerRadius = 10
        layer.borderColor = UIColor.blue.cgColor
        layer.borderWidth = 2
        backgroundColor = .white
    }

    @objc func didTapButton(_ sender: Any) {
        if let annotation = annotation {
            delegate?.calloutTapped(for: annotation)
        }
    }

    fileprivate func addBackgroundButton(to view: UIView) {
        let button = UIButton(type: .custom)
        button.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(button)
        NSLayoutConstraint.activate([
            button.topAnchor.constraint(equalTo: view.topAnchor),
            button.bottomAnchor.constraint(equalTo: view.bottomAnchor),
            button.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            button.trailingAnchor.constraint(equalTo: view.trailingAnchor)
        ])
    }
}

// our annotation view for our pickup annotations

class PickupLocationAnnotationView: MKPinAnnotationView {
    weak var calloutView: UIView?

    override func prepareForDisplay() {
        super.prepareForDisplay()
        canShowCallout = false
    }

    // make sure that hits in callout are recognized as not-deselecting the annotation view

    override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
        if let hitView = super.hitTest(point, with: event) { return hitView }

        if let calloutView = calloutView {
            let point = convert(point, to: calloutView)
            return calloutView.hitTest(point, with: event)
        }

        return nil
    }

    // lets move the add callout here, inside the annotation view class,
    // so the annotation view can keep track of its callout

    func addCallout(delegate: CalloutViewDelegate) {
        removeCallout()

        let view = CalloutView(annotation: annotation, delegate: delegate)
        view.translatesAutoresizingMaskIntoConstraints = false
        addSubview(view)
        calloutView = view

        NSLayoutConstraint.activate([
            view.centerXAnchor.constraint(equalTo: centerXAnchor),
            view.bottomAnchor.constraint(equalTo: topAnchor, constant: -10)
        ])
    }

    func removeCallout() {
        calloutView?.removeFromSuperview()
    }
}

// random view controller example that adds an annotation

class ViewController: UIViewController {
    @IBOutlet weak var mapView: MKMapView!

    override func viewDidLoad() {
        super.viewDidLoad()

        let coordinate = CLLocationCoordinate2D(latitude: 37.332693, longitude: -122.03071)
        mapView.camera = MKMapCamera(lookingAtCenter: coordinate, fromDistance: 1_000, pitch: 0, heading: 0)
        mapView.register(PickupLocationAnnotationView.self, forAnnotationViewWithReuseIdentifier: MKMapViewDefaultAnnotationViewReuseIdentifier)

        let hours = """
            Mon to Thu 10am-7pm
            Fri 12pm-9pm
            Sat 10am-11pm
            """
        let annotation = PickupLocationAnnotation(hours: hours)
        annotation.coordinate = coordinate
        mapView.addAnnotation(annotation)
    }
}

// the selecting and deselecting of annotation views

extension ViewController: MKMapViewDelegate {
    func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {
        if let view = view as? PickupLocationAnnotationView {
            view.addCallout(delegate: self)
        }
    }

    func mapView(_ mapView: MKMapView, didDeselect view: MKAnnotationView) {
        if let view = view as? PickupLocationAnnotationView {
            view.removeCallout()
        }
    }
}

// the delegate conformance so view controller can know when the callout button was tapped

extension ViewController: CalloutViewDelegate {
    func calloutTapped(for annotation: MKAnnotation) {
        print(#function)
    }
}