如何解决此错误？ - Class'ViewController'没有初始值设定项

Question

我已经UILabel在swift中以编程方式创建但它给了我以下错误:

类'ViewController'没有初始值设定项

代码:

class ViewController: UIViewController {

    let lbl_LastName: UILabel!

    override func viewDidLoad() {
        super.viewDidLoad()
        lbl_LastName.frame = CGRectMake(10, 230, 300, 21)
        self.view.addSubview(lbl_LastName)   
    }
}

Answer 1

改变let lbl_LastName: UILabel!以var lbl_LastName: UILabel!