例子
import SwiftUI
import Combine
class MyDevice: ObservableObject {
//let objectWillChange = ObservableObjectPublisher()
var isShaken: Bool = false {
willSet {
self.objectWillChange.send()
}
}
}
struct ContentView: View {
@ObservedObject var model = MyDevice()
var body: some View {
VStack {
Text("\(model.isShaken.description)").onTapGesture {
self.model.isShaken.toggle()
}
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
取消注释
let objectWillChange = ObservableObjectPublisher()
它停止工作。
不要重新定义你自己的 ObservableObjectPublisher()
检查
import SwiftUI
import Combine
class MyDevice: ObservableObject {
//let objectWillChange = ObservableObjectPublisher()
var isShaken: Bool = false {
willSet {
self.objectWillChange.send()
}
}
}
struct ContentView: View {
@EnvironmentObject var model: MyDevice
var body: some View {
VStack {
Text("\(model.isShaken.description)").onTapGesture {
self.model.isShaken.toggle()
}
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView().environmentObject(MyDevice())
}
}
在 SceneDelegate.swift 中
func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
// Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
// If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
// This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
// Create the SwiftUI view that provides the window contents.
let contentView = ContentView().environmentObject(MyDevice())
//let contentView = ContentView()
// Use a UIHostingController as window root view controller.
if let windowScene = scene as? UIWindowScene {
let window = UIWindow(windowScene: windowScene)
window.rootViewController = UIHostingController(rootView: contentView)
self.window = window
window.makeKeyAndVisible()
}
}
它按预期工作。
好的，使用震动检测器，
myDevice?.isShaken = true
永远不会运行，因为 myDevice 是 nil
解决办法
使您的模型全局可用，因为在 SwiftUI 中我们没有工具如何使其可用于 ShakableViewController，或者将其用作其 init 的参数
SwiftDelegate.swift
import UIKit
import SwiftUI
let model = MyDevice()
class SceneDelegate: UIResponder, UIWindowSceneDelegate {
var window: UIWindow?
func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
// Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
// If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
// This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
// Create the SwiftUI view that provides the window contents.
let contentView = ContentView().environmentObject(model)
//let contentView = ContentView()
// Use a UIHostingController as window root view controller.
if let windowScene = scene as? UIWindowScene {
let window = UIWindow(windowScene: windowScene)
window.rootViewController = UIHostingController(rootView: contentView)
self.window = window
window.makeKeyAndVisible()
}
}
func sceneDidDisconnect(_ scene: UIScene) {
// Called as the scene is being released by the system.
// This occurs shortly after the scene enters the background, or when its session is discarded.
// Release any resources associated with this scene that can be re-created the next time the scene connects.
// The scene may re-connect later, as its session was not neccessarily discarded (see `application:didDiscardSceneSessions` instead).
}
func sceneDidBecomeActive(_ scene: UIScene) {
// Called when the scene has moved from an inactive state to an active state.
// Use this method to restart any tasks that were paused (or not yet started) when the scene was inactive.
}
func sceneWillResignActive(_ scene: UIScene) {
// Called when the scene will move from an active state to an inactive state.
// This may occur due to temporary interruptions (ex. an incoming phone call).
}
func sceneWillEnterForeground(_ scene: UIScene) {
// Called as the scene transitions from the background to the foreground.
// Use this method to undo the changes made on entering the background.
}
func sceneDidEnterBackground(_ scene: UIScene) {
// Called as the scene transitions from the foreground to the background.
// Use this method to save data, release shared resources, and store enough scene-specific state information
// to restore the scene back to its current state.
}
}
ContentView.swift
import SwiftUI
import Combine
struct ShakableViewRepresentable: UIViewControllerRepresentable {
class Coordinator: NSObject {
var parent: ShakableViewRepresentable
init(_ parent: ShakableViewRepresentable) {
self.parent = parent
}
}
func makeCoordinator() -> ShakableViewRepresentable.Coordinator {
Coordinator(self)
}
func makeUIViewController(context: Context) -> ShakableViewController {
ShakableViewController()
}
func updateUIViewController(_ uiViewController: ShakableViewController, context: Context) {}
}
class ShakableViewController: UIViewController {
override func motionBegan(_ motion: UIEvent.EventSubtype, with event: UIEvent?) {
guard motion == .motionShake else { return }
model.isShaken.toggle()
print(model.isShaken)
}
}
class MyDevice: ObservableObject {
//let objectWillChange = ObservableObjectPublisher()
var isShaken: Bool = false {
willSet {
self.objectWillChange.send()
}
}
}
struct ContentView: View {
@EnvironmentObject var model: MyDevice
var body: some View {
VStack {
ShakableViewRepresentable()
.allowsHitTesting(false)
Text(self.model.isShaken ? "The device has been shaken" : "No shaking has occurred").onTapGesture {
self.model.isShaken.toggle()
}
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView().environmentObject(MyDevice())
}
}
而且它可以工作，至少在我的设备上 :-)
没有声音，但会打印
true
false
true
false
true
每一次摇一摇的客串