创建主入口 main.swift:

import UIKitUIApplicationMain(	Process.argc, Process.unsafeArgv,	NSStringFromClass(MainApp), NSStringFromClass(MainAppDelegate))

创建 app.swift, 对应 MainApp 和 MainAppDelegate 的实现:

import UIKitclass MainApp: UIApplication {	override func sendEvent(event: UIEvent) {		super.sendEvent(event)	}}class MainAppDelegate: UIResponder, UIApplicationDelegate {	var window: UIWindow?	func application(app: UIApplication, didFinishLaunchingWithOptions opt: [NSObject: AnyObject]?) -> Bool {		self.window = UIWindow(frame: UIScreen.mainScreen().bounds)		self.window!.rootViewController = UIViewController()		self.window!.backgroundColor = UIColor.whiteColor()		self.window!.makeKeyAndVisible()		self.window!.AddSubview {			let label = UILabel(frame: self.window!.frame)			label.textAlignment = .Center			label.text = "你好, UIKit!"			return label		}		return true	}}extension UIView {	func AddSubview(subview: ()->UIView) {		self.addSubview(subview())	}}

运行效果: