如何在viewDidLoad（）Swift2中初始化变量

Question

I am trying to create a stopWatch app as a part of learning swift. Coming from Java I am having a hard time figuring out how to initialize a variable. Relevant code of viewcontroller:

var timerRunning = false

var timer: NSTimer = NSTimer() //first initialization I want to remove this initialization and leave it as nil


override func viewDidLoad() {
    super.viewDidLoad()
// second initialization
    timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: #selector(ViewController.timeChanged), userInfo: nil, repeats: true)
}

func timeChanged(){
    print("1 second")
}

The problem I am facing is double initialization of the timer variable which I think is redundant and cannot set to nil. My goal is to use timer variable in a couple of functions and initialize it on a button pressed event. The above approach works but I am looking for some cleaner/correct implementations. Thank You

Answer 1

将您的计时器变量声明为可选变量，以使其最初具有nil值，之后您可以在按钮事件中实例化它。