init_example.swift

// Option without self
class Foo1 {
    private let controller: UIViewController = {
        return UIStoryboard(name: "Main", bundle: nil).instantiateInitialViewController()!
    }()
    
    private lazy var window: UIWindow = {
        let window = UIWindow(frame: UIScreen.mainScreen().bounds)
        window.backgroundColor = UIColor.whiteColor()
        window.makeKeyAndVisible()
        return window
    }()

    init() {
        
    }
}

// First option using self
class Foo2 {
    private let controller: UIViewController = {
        return UIStoryboard(name: "Main", bundle: nil).instantiateInitialViewController()!
    }()
    
    private lazy var window: UIWindow = { [unowned self] in
        let window = UIWindow(frame: UIScreen.mainScreen().bounds)
        window.backgroundColor = UIColor.whiteColor()
        window.makeKeyAndVisible()
        window.rootViewController = self.controller
        return window
    }()

    init() {
        _ = window
    }
}

// Second option using self
class Foo3 {
    private let controller: UIViewController = {
        return UIStoryboard(name: "Main", bundle: nil).instantiateInitialViewController()!
    }()
    
    private let window: UIWindow = {
        let window = UIWindow(frame: UIScreen.mainScreen().bounds)
        window.backgroundColor = UIColor.whiteColor()
        window.makeKeyAndVisible()
        return window
    }()

    init() {
        setup()
    }
    
    func setup() {
        self.window.rootViewController = self.controller
    }
}