Class 没有初始值设定项?

Class has no initializers?

我已经为此工作了大约一个小时。我在这个视线中查看了其他问题,但出现了完全相同的错误,并尝试了解决方案。我仍然收到错误。这是我的代码:

class Links: UIViewController {

let firstLinkButton: UIButton?

let secondLinkButton: UIButton?


@IBAction func firstLinkButton(sender: AnyObject) {

    UIApplication.sharedApplication().openURL(NSURL(string: "http://www.google.com")!)

}

@IBAction func secondLinkButton(sender: AnyObject) {

    UIApplication.sharedApplication().openURL(NSURL(string: "http://www.bing.com")!)



}


override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

}

这可能是今天视线中最简单的问题,但非常感谢任何意见或建议。提前致谢。

P.S.: R.I.P.我的声誉。

制作按钮var

var firstLinkButton: UIButton?

var secondLinkButton: UIButton?

let 常量必须立即初始化。