Swift 暂停我的 AR 会话并清除变量和锚点的功能

要做到这一点，一种方法是将UIKit从SwiftUI中分离出来，并拥有一个共同的真理来源，在那里这两个框架可以相互通信.

struct InitiateARView: View {
    @StateObject var vm = ARPreparationViewModel()
    
    var body: some View {
        VStack {
            if vm.isLoading {
                Button("Start", action: {
                    vm.prepareAR()
                })
                
            } else {
                ZStack {
                    ARExperience_UI(vm: vm) //Your experiece would change to include the shared VM
                        .edgesIgnoringSafeArea(.all)
                    VStack {
                        HStack {
                            Spacer()
                            Button("Stop AR", action: {
                                //Make SwiftUI changes
                                vm.clearAR() // Then you can access UIKit via the VM
                            })
                        }
                        Spacer()
                    }
                }
            }
        }
    }
}

共享的真相来源应该是这样的.

//Works with both SwiftUI and UIKit
class ARPreparationViewModel: ObservableObject{
    //reference to UIKit, will be nil until set by ViewController init.
    @Published var vc: ARExperienceVC?
    @Published var isLoading: Bool = false
    
    deinit {
        vc = nil
    }
    
    func prepareAR() {
        guard let vc = vc else {
            print("Missing View Controller")
            return
        }
        vc.prepareAR()
    }
    func clearAR() {
        guard let vc = vc else {
            print("Missing View Controller")
            return
        }
        //Make any source of truth changes
        vc.clearAR()
    }
}

然后，UIViewControllerRepresentable代码将被简化为只创建新的UIViewController，这只是一个桥梁.

// SwiftUI
struct ARExperience_UI: UIViewControllerRepresentable { //Change to a UIViewControllerRepresentable
    let vm: ARPreparationViewModel
    
    func makeUIViewController(context: Context) -> some UIViewController {
        ARExperienceVC(vm: vm) // Create the new ViewController with all the UIKit Code
    }
    func updateUIViewController(_ uiViewController: UIViewControllerType, context: Context) {
        
    }
}

UIKit代码执行繁重的任务.

// Keep UIKit code here
class ARExperienceVC: UIViewController {
    let vm: ARPreparationViewModel

    lazy var arView: ARView = {
        let arView = ARView(frame: .zero)
        arView.session.delegate = self
        
        return arView
    }()
    
    init(vm: ARPreparationViewModel) {
        self.vm = vm
        super.init(nibName: nil, bundle: nil)
        self.vm.vc = self //Without this the source of truth won't have access to the ViewController
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    deinit {
        self.vm.vc = nil
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        view.addSubview(arView)
        arView.pinToSuperview(self.view) // This lest SwiftUI control the size because the view will be attached to the bordering anchors.
    }
    
    func prepareAR() {
        print("\(type(of: self)) :: \(#function)")
    }
    func clearAR() {
        print("\(type(of: self)) :: \(#function)")
        //Make UIKit changes.
    }
}

extension ARExperienceVC: ARSessionDelegate {
    func session(_ session: ARSession, didAdd anchors: [ARAnchor]) {
        
    }

    func session(_ session: ARSession, didUpdate anchors: [ARAnchor]) {

    }
}

extension UIView{
    func pinToSuperview(_ superView: UIView){
        self.translatesAutoresizingMaskIntoConstraints = false
        self.topAnchor.constraint(equalTo: superView.topAnchor).isActive = true
        self.bottomAnchor.constraint(equalTo: superView.bottomAnchor).isActive = true
        self.leadingAnchor.constraint(equalTo: superView.leadingAnchor).isActive = true
        self.trailingAnchor.constraint(equalTo: superView.trailingAnchor).isActive = true
    }
}