Swift 从不同的控制器调用视图控制器或从不同的控制器调用警报

Question

我想知道是否可以在 swift 中调用警报或控制器或从单独的控制器中简化功能。我想从 viewcontroller1 访问我的警报到应用程序委托，我想在应用程序委托中触发它而不是创建另一个警报，我有一个目的为什么我想在应用程序委托中触发它。这可能吗？谢谢你。我可以在应用程序委托的视图控制器 1 中调用我的警报吗？而且我想在应用程序委托中从视图控制器 1 调用我的 collection 视图，这可能吗？

collection 查看代码

 func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        // handle tap events
//        print("You selected cell #\(indexPath.item)!")
//        print("emong gepili:" , titleArray[indexPath.row])


        if indexPath.row == 0 {
            var a = loggedInUsername
            if ((a?.range(of: "mother")) != nil) {
                  performSegue(withIdentifier: "goToSegue", sender: nil)
                print("yolo")
            }else {
                print("do nothing")
                var alert = UIAlertController(title: "No Access", message: "You Can't Add A Chore", preferredStyle: UIAlertControllerStyle.alert)
                alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.default, handler: nil))
                self.present(alert, animated: true, completion: nil)
            }

        } else {


            print("You selected cell #\(indexPath.item)!")

            if let getTempDetails: [String : Any] = getAllDetail[indexPath.row],
                let name = getTempDetails["name"] as? String,
                let id = getTempDetails["id"] as? Int,
                let description = getTempDetails["desc"] as? String,
                let chorereward = getTempDetails["reward"] as? String,
                let choreschedule = getTempDetails["sched"] as? String

                //                let chorescheds = getTempDetails["sched"] as? String

//                let parent = getTempDetails["parent"] as? String,
//                let child = getTempDetails["child"] as? String,
//                let occurrence = getTempDetails["occurrence"] as? String,
//                let status = getTempDetails["date_created"] as? String,
//                let datec = getTempDetails["status"] as? String,
//                let datemod = getTempDetails["date_modified"] as? String {
            {
                let stat = getTempDetails["status"] as! NSDictionary
                let statname = stat["name"]
                let str = getTempDetails["occurrence"] as! NSDictionary
                let strname = str["name"]

警报代码

let alert = UIAlertController(title: "Chore Name: \(getTempDetails["name"] as! String)", message: "", preferredStyle:
                    UIAlertControllerStyle.alert)


                alert.addTextField { (choreField) in
                    choreField.text = getTempDetails["name"] as! String
                }



                alert.addTextField { (rewardField) in
                    //                    rewardField.text =  getTempDetails["reward"] as! String
                    let rewardData = getTempDetails["reward"]
                    let reward = (rewardData as! NSString).integerValue
                    rewardField.placeholder = "Chore Reward"
                    rewardField.text = String(reward)
                }

                alert.addTextField { (idField) in
                    idField.placeholder = "Email"
                    var a =  "\(getTempDetails["id"] as? Int ?? 0)!"
                    a.removeLast()
                    idField.text = a
                }
                ........

Answer 1

创建一个新的 NSObject class 并将全局函数作为其 class 函数，如下例所示

  class wrapperClass: NSObject
    {
       class func alert(_ title : String, message : String, view:UIViewController)
        {
            let alert = UIAlertController(title:title, message:  message, preferredStyle: UIAlertControllerStyle.alert)
            alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil))
            view.present(alert, animated: true, completion: nil)
        }
    }

用法

wrapperClass.alert("Service Remainder", message: "Enter Username", view: self)

注意 - AppDelgate 不是视图控制器，因此您不能在 AppDelegate 中调用此函数您可以在第一个显示的控制器中做一件事

Answer 2

因此，根据我的理解，您正试图在 AppDelegate 期间显示警报。

但是不可能在那里显示，基本上会发生的是 AppDelegate 将在应用程序启动时被调用，之后将调用堆栈中第一个的视图控制器。

如果您在 AppDelegate 中设置了任何条件，并且在这种情况下想要在那里显示警报，

可以使用

func showAlertAppDelegate(title : String,message : String,buttonTitle : String,window: UIWindow){ 
let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert) 
alert.addAction(UIAlertAction(title: buttonTitle, style: UIAlertActionStyle.default, handler: nil)) 
window.rootViewController?.present(alert, animated: true, completion: nil) 
}

并像这样使用它：

showAlertAppDelegate(title: "Alert!", message: "Message", buttonTitle: "Ok", window: self.window!)

注意：-此警报将在调用 App 委托后加载的第一个 VC 上显示。

Answer 3

使用此扩展程序在应用程序中的任何位置显示警报或 ViewController：

extension UIApplication {
class func topViewController(controller: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {
    if let navigationController = controller as? UINavigationController {
        return topViewController(controller: navigationController.visibleViewController)
    }
    if let tabController = controller as? UITabBarController {
        if let selected = tabController.selectedViewController {
            return topViewController(controller: selected)
        }
    }
    if let presented = controller?.presentedViewController {
        return topViewController(controller: presented)
    }
    return controller
}

}

如何使用？

UIApplication.topViewController()?.present(yourAlertVC, animated: true, completion: nil)

Now What I've understood from your problem,

Clearly calling collection view's delegate methods from AppDelegate is a wrong approach as iOS Geek said it is Singleton. But what you can do you can create a observer for that Like the below one.

NotificationCenter.default.addObserver(self, selector: #selector(theMethodWhichYouWanaHit(params:)), name: Notification.Name("Notification_Name"), object: nil)

方法如下：

func theMethodWhichYouWanaHit(_ params : Notification){
    collectionView.delegate = self
    collectionView.dataSource = self
    let yourObject = params.object
    // use the object it has all the data in it (aka objectToBePassed )
}

大功告成！

现在，只需 post 观察者就像一个函数调用一样，它会完成剩下的工作。:

NotificationCenter.default.post(name: NSNotification.Name("Notification_Name"), object: objectToPassed, userInfo:nil)

为了移除观察者:

NotificationCenter.default.removeObserver(self, name: NSNotification.Name("Notification_Name"), object: nil)

Swift 从不同的控制器调用视图控制器或从不同的控制器调用警报

Swift calling a view controller from a different controller or calling an alert from different controller

alert

ios

swift