Question

我尝试使用Timer #selector从AppDelegate中的MainViewController访问一个方法。但它给了我一个错误：＆＃34;无法识别的选择器被发送到实例＆＃34;

在我的AppDelegate中，我有一个计时器;

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

        MainViewController().test() //this line prints successful!

        _ = Timer.scheduledTimer(timeInterval: 5.0, target: self, selector: #selector(MainViewController.test), userInfo: nil, repeats: true)

}

在我的MainViewController中;

func test() {
   print("successful!")
}

当我将该功能移至AppDelegate时，它的作用为#selector(self.test)

难道难以置信，还是我错过了什么？

Answer 1

试试这个，将MainViewController添加为AppDelegate中的var，然后您可以将其用作scheduledTimer的目标，而#selector则必须通过test var controller = MainViewController() func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool { // Override point for customization after application launch. _ = Timer.scheduledTimer(timeInterval: 5.0, target: controller, selector: #selector(ViewController.test), userInfo: nil, repeats: true) return true } 1}}

npm i dexie@next  --save

我希望这可以帮到你，它有效

Answer 2

这可能是实现目标的便捷方式：

class AppDelegate : UIApplicationDelegate {
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

    let view = MainViewController()
    view.setupTimer()
}

class MainViewController: UIViewController {
var timer: Timer!
func test(sender: NSTimer!) {
    /* code */
}

func setupTimer() {
    timer = Timer.scheduledTimerWithTimeInterval(timeInterval: 5.0, target: controller, selector: #selector(test), userInfo: nil, repeats: true)
}

Answer 3

目标是必须拥有方法本身的目标，在这种情况下，app委托没有方法test并且会崩溃。通过以下方式做一些事情可以正常工作：

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

        let mainVC = MainViewController()

        _ = Timer.scheduledTimer(timeInterval: 5.0, target: mainVC, selector: #selector(MainViewController.test), userInfo: nil, repeats: true)

}

这样做，你告诉计时器它必须调用的选择器是在MainViewController的特定实例中

Swift - Timer #selector不能与其他控制器方法一起使用

3 个答案: