ios - 尝试在 60 秒后触发警报框。这是行不通的

Question

我正在尝试让此警报在过去两个小时内正常工作。我不知道为什么不会。我是否有可能让它在那里工作？

class TimerHolder : ObservableObject {
@State var showResults = false
var timer : Timer!
@Published var count = 0
func start() {
    self.timer?.invalidate()
    self.count = 0
    self.timer = Timer.scheduledTimer(withTimeInterval: 1, repeats: true) {
        _ in
       // self.count += 1
       // print(self.count)

        if self.count < 60 {
            self.count += 1
            print(self.count)

        }else{


            _ = Alert(title: Text("Warning"), message: Text("The timer will start as soon as you press OK. "), primaryButton: .default(Text("OK"), action: {})
                , secondaryButton: .cancel(Text("Not yet.")))
        }
            }
        }
    }





struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

Answer 1

看来您要左转三圈才能右转。 ObservableObject 应该只是数据的持有者。

我认为最好在 ObservableObject 之外执行此操作，并且将计时器保存在 View 或 ViewController 中。

类 StartViewController: UIViewController {

var displayTimer:定时器!

override func viewDidLoad() {
    super.viewDidLoad()

    //setup the Timer
    displayTimer = Timer.scheduledTimer(timeInterval: 60.0,
                         target: self,
                         selector: #selector(self.displayTimerFired(_:)),
                         userInfo: nil,
                         repeats: false)

}

@objc func displayTimerFired(_ timer: Timer) {

    let alertController = UIAlertController(title: "60 Seconds...", message: "60 Seconds have elapsed.", preferredStyle: .alert)
    alertController.addAction(UIAlertAction(title: "OK",  style: .default, handler: nil))
    self.present(alertController, animated: true, completion: nil)

    //clean up timer
    displayTimer.invalidate()


}

}

编辑

抱歉，刚刚意识到您正在使用 SwiftUI

结构TimerView: View {

let timer = Timer.publish(every: 60, on: .main, in: .common).autoconnect()

var body: some View {
        .onReceive(timer) { _ in
             _ = Alert(title: Text("Warning"), message: Text("The timer will start as soon as you press OK. "), primaryButton: .default(Text("OK"), action: {})
            , secondaryButton: .cancel(Text("Not yet.")))

        }
}

}