所以目前在 XCode 13 中，当我第一次创建项目时，xcode 会为 iOS 14.0+ 生成项目结构。
我是 iOS 新手，我想创建一个针对 iOS 13.0+ 的项目。如何告诉 XCode 为 iOS 13.0+ 生成项目模板？
【问题讨论】：
将此添加到.swift 文件中
import UIKit
import SwiftUI
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
return true
}
// MARK: UISceneSession Lifecycle
func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
// Called when a new scene session is being created.
// Use this method to select a configuration to create the new scene with.
return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
}
func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
// Called when the user discards a scene session.
// If any sessions were discarded while the application was not running, this will be called shortly after application:didFinishLaunchingWithOptions.
// Use this method to release any resources that were specific to the discarded scenes, as they will not return.
}
}
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()
// 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.
}
}
然后更改Info.plist中的Application Scene Manifest条目
确保您删除/注释掉 @main 并且应用以 ContentView 开头
【讨论】：
我已经通过以下方法创建了一个兼容 iOS 13 的 SwiftUI 项目。这对于 iOS 13 有一个块，对于 iOS 14+ 有另一个块
第 0 步：使用 XCode 创建 SwiftUI 项目
这将有一个主 swift 文件和一个 ContentView.swift。
// ContentView.swift
import SwiftUI
struct ContentView: View {
var body: some View {
Text("Hello")
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
第1步：更新Info.plist如下。
第 2 步：使用以下代码更新主 swift 文件。
import UIKit
import SwiftUI
@main
struct MainApp {
static func main() {
if #available(iOS 14.0, *) {
MyView.main()
} else {
UIApplicationMain(
CommandLine.argc,
CommandLine.unsafeArgv,
nil,
NSStringFromClass(AppDelegate.self))
}
}
}
@available(iOS 14.0, *)
struct MyView: App {
var body: some Scene {
WindowGroup {
ContentView() // Add another view with content Text("From iOS 14+") to test both block runs
}
}
}
class AppDelegate: UIResponder, UIApplicationDelegate {
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
return true
}
func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
}
func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
}
}
class SceneDelegate: UIResponder, UIWindowSceneDelegate {
var window: UIWindow?
func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
let contentView = ContentView() // Add another view with content Text("From iOS 13") to test both block runs
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) {
//
}
func sceneDidBecomeActive(_ scene: UIScene) {
//
}
func sceneWillResignActive(_ scene: UIScene) {
//
}
func sceneWillEnterForeground(_ scene: UIScene) {
//
}
func sceneDidEnterBackground(_ scene: UIScene) {
//
}
}
第 3 步：测试
XCode -> Preferences -> Components安装iOS 13模拟器
if #available(iOS 14, *) {} 条件，对类或其他对象使用@available(iOS 15, *)。【讨论】：