Swift - 更新/刷新显示时间的标签

Question

我有一个以 12 小时格式显示当前时间的标签。

但是，它不会在每次分钟/小时更改时更新/刷新时间。

我需要它在时间变化时自动将标签更改为当前时间。

Answer 1

Swift 3 解决方案

class ViewController {

    @IBOutlet weak var timeLabel: UILabel!
    var timer: Timer?

    let formatter: DateFormatter = {
        let tmpFormatter = DateFormatter()
        tmpFormatter.dateFormat = "hh:mm a"
        return tmpFormatter
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        timer = Timer.scheduledTimer(timeInterval: 60, target: self, selector: #selector(self.getTimeOfDate), userInfo: nil, repeats: true)
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        timer?.invalidate()
    }

    func getTimeOfDate() {
        var curDate = Date()

        timeLabel.text = formatter.string(from: curDate)
    }

}

Answer 2

用您的 ViewController 代码替换以下代码，然后将 IBOutlet 连接到 showTimeLbl

class ViewController: UIViewController {

    @IBOutlet weak var showTimeLbl: UILabel!
    var timeCount:Int = 0
    var timer:Timer!

    override func viewDidLoad() {
        super.viewDidLoad()

        if(timer != nil)
        {
            timer.invalidate()
        }
        timer = Timer(timeInterval: 1.0, target: self, selector: #selector(ViewController.timerDidFire), userInfo: nil, repeats: true)
        RunLoop.current.add(timer, forMode: RunLoopMode.commonModes)

    }

    func timerDidFire()
    {
        timeCount += 1

        showTimeLbl.text = NSString(format: "%02d:%02d:%02d", timeCount/3600,(timeCount/60)%60,timeCount%60) as String
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(true)
        timer?.invalidate()
        timer = nil
    }

}