创建 UIKit 项目教程

一、打开 XCode，选择 iOS 下的 App，然后点 Next

二、Interface 选择 Storyboard，然后点 Next

三、删掉 Main.storyboard

四、删掉 SceneDelegate.swift

五、AppDelegate.swift 只保留第一个函数

六、在 AppDelegate.swift 文件里的 application 函数改成这样

Swift 复制代码

class AppDelegate: UIResponder, UIApplicationDelegate {
	var window: UIWindow?
	
	func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
		window = UIWindow(frame: UIScreen.main.bounds)
		window?.rootViewController = ViewController()
		window?.makeKeyAndVisible()
		return true
	}
}

七、删掉在 Info.plist 的 Application Scene Manifest

八、在 building settings 里搜 storyboard，然后把 UIKit Main Storyboard File Base Name 的 "Main" 置空

九、验证

把这段代码复制进 ViewController.swift 中

Swift 复制代码

import UIKit

class ViewController: UIViewController {
	var label = UILabel()
	
	override func viewDidLoad() {
		super.viewDidLoad()
		view.backgroundColor = .white
		view.addSubview(label)
		
		configLabel()
		layoutLabel()
	}

	func configLabel() {
		label.text = "Hello UIKit"
		label.textColor = .black
		label.font = .systemFont(ofSize: 18)
		label.textAlignment = .center
	}
	
	func layoutLabel() {
		label.translatesAutoresizingMaskIntoConstraints = false
		
		NSLayoutConstraint.activate([
			label.centerXAnchor.constraint(equalTo: view.centerXAnchor),
			label.centerYAnchor.constraint(equalTo: view.centerYAnchor),
			label.leadingAnchor.constraint(greaterThanOrEqualTo: view.leadingAnchor, constant: 20),
			label.trailingAnchor.constraint(lessThanOrEqualTo: view.trailingAnchor, constant: -20)
		])
		
	}
}

会看到如下结果：