小编man*_*ken的帖子

我在 Xcode 控制台中看到一条消息，它是Received memory pressure event 1 vm pressure 0. 我不确定是什么原因造成的，为什么但我知道当我在相机视图控制器中时会打印。我猜这没什么可担心的（还），但它是否指向我应该尽快修复的问题？

FirstViewController: UIViewController {

    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        let image = info[UIImagePickerController.InfoKey.editedImage] as! UIImage
        let croppedImage = cropToBounds(image: image, width: 10, height: 10)
        self.productImage.image = croppedImage
        print("size: \(croppedImage.size)")
        print("original size: \(image.size)")
        self.dismiss(animated: true, completion: nil)
    }

    func setupCameraPicker() {
        if UIImagePickerController.isSourceTypeAvailable(.camera) {
            let imagePicker = UIImagePickerController()
            imagePicker.delegate = self
            imagePicker.sourceType = .camera;
            imagePicker.allowsEditing = true
            self.present(imagePicker, animated: true, completion: nil)
        }
    } …

我正在通过构建一个具有“设置视图”的应用程序来测试 SwiftUI，我们将其称为 ViewB。该视图有一个列表，您可以在其中选择语言。第一个视图 ViewA 有 2 个按钮“打开”或“选择语言”。

我想做的是，从ViewA开始，打开ViewB，选择一种语言，然后自动回到ViewA。这就是我所做的：

视图A

var body: some View {
    NavigationView {
        VStack(alignment: .center) {
            Button(action: start) {
                Text("Open")
            }
            NavigationLink(destination: ViewB()) {
                Text("Change language")
            }
        }
        .sheet(isPresented: $presenting) {
            DemoView(code: self.langugage ?? "SE") { result in }
        }
    }
}

这就是我在 ViewB 上取得的进展：

var body: some View {
    List(langs) { item in
        HStack {
            NavigationLink(destination: ViewA(presentingSuccessScreen: self.$isPresentingSuccessScreen, language: item.code)) {
                Image(item.icon).resizable().frame(width: 40, height: 40)
                Text(item.market)
            }.frame(height: 64)
        }
        .navigationBarTitle(Text("Select Language"), displayMode: .inline)
        .navigationBarBackButtonHidden(true)
        .navigationBarItems(trailing:
            Button("Cancel") …