iOS SwiftUI：如何在视图中检测 UITapGesture 的位置？

Question

所以我正在使用 Mapbox。 map 结构符合 UIViewRepresentable 协议。在我的 makeUIView() 函数中，我创建了一个点击手势识别器并将其添加到地图视图中。

struct Map: UIViewRepresentable {

    private let mapView: MGLMapView = MGLMapView(frame: .zero, styleURL: MGLStyle.streetsStyleURL)

    func makeUIView(context: UIViewRepresentableContext<Map>) -> MGLMapView {
        mapView.delegate = context.coordinator
        let gestureRecognizer = UITapGestureRecognizer(target: context.coordinator, action: Selector("tappedMap"))
        mapView.addGestureRecognizer(gestureRecognizer)
        return mapView
    }

    func updateUIView(_ uiView: MGLMapView, context: UIViewRepresentableContext<Map>) {
        print("Just updated the mapView")
    }

    func makeCoordinator() -> Map.Coordinator {
        Coordinator(appState: appState, self)
    }

    // other functions that make the struct have functions required by Mapbox 

    func makeCoordinator() -> Map.Coordinator {
        Coordinator(self)
    }

    final class Coordinator: NSObject, MGLMapViewDelegate {
        var control: Map

        //a bunch of delegate functions

        @objc func tappedMap(sender: UITapGestureRecognizer) {
            let locationInMap = sender.location(in: control)
            let coordinateSet = sender.convert(locationInMap, toCoordinateFrom: control)
        }
    }
}

tappedMap 函数中的两行均未正确编译...此外，当我在 tappedMap 的参数中包含“sender: UITapGestureRecognizer”时，我在点击 mapView 时会导致应用程序崩溃--如果我删除参数，那么至少可以正确调用该函数而不会崩溃。请帮忙

Answer 1

好的，第一个问题是您在 tapGesture 声明中的选择器定义。改成这样：

let gestureRecognizer = UITapGestureRecognizer(target: context.coordinator, action: #selector(Coordinator.tappedMap(sender:)))

此外，您需要管理手势识别器的优先级，因为 MGLMapView 内部包含 UIGestureRecognizer 逻辑。我发现了here的讨论：

将自己的手势识别器添加到 MGLMapView 将阻止 MGLMapView 内置相应的手势识别器。避免 冲突，定义哪个手势优先。

您可以在您的项目中尝试此代码（几乎是从上面的链接页面复制的）编辑：我需要更改原始答案中的行顺序：

let gestureRecognizer = UITapGestureRecognizer(target: context.coordinator, action: Selector("tappedMap"))

// HERE'S THE NEW STUFF:
for recognizer in mapView.gestureRecognizers! where recognizer is UITapGestureRecognizer {
    gestureRecognizer.require(toFail: recognizer)
}

mapView.addGestureRecognizer(gestureRecognizer)

编辑：我能够对此进行测试。

我对 tappedMap 选择器中的逻辑有点困惑：也许你的意思是这样的？

@objc func tappedMap(sender: UITapGestureRecognizer) {
    let locationInMap = sender.location(in: control.mapView)
    let coordinateSet = sender.view?.convert(locationInMap, to: control.mapView)
}