如何从另一个View Controller中的变量获取值 ViewController.swift的片段 PrefsViewController的片段

问题描述

我试图从ViewController的PrefsViewController中的4个不同变量中获取值，但是当关闭PrefsViewController时，值会重置。

ViewController.swift的片段

class ViewController: NSViewController,NSWindowDelegate { 
    
    var triesEnabled = false
    var minNumber = 0
    var maxnumber = 20
    var maxTries = 3
    
    @objc func applyPrefs() {
        let mainSB = nsstoryboard(name: "Main",bundle: nil)
        let prefsVC: PrefsViewController = mainSB.instantiateController(withIdentifier: "prefsViewController") as! PrefsViewController
        minNumber = prefsVC.prefsMinNum
        maxnumber = prefsVC.prefsMaxnum
        triesEnabled = prefsVC.prefsTriesEnabled
        maxTries = prefsVC.prefsMaxTries
        print("\(minNumber) \(maxnumber) \(triesEnabled) \(maxTries)") // here I can see that it has been reset to the default values
        resetGame(minRange: minNumber,maxrange: maxnumber,isTriesEnabled: triesEnabled,triesLimit: maxTries)
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        NotificationCenter.default.addobserver(self,selector: #selector(applyPrefs),name: Notification.Name("notifyApplyPrefs"),object: nil )
        resetGame(minRange: minNumber,triesLimit: maxTries)
    }
}

PrefsViewController的片段

class PrefsViewController: NSViewController {
    
    var triesOn = false
    
    var prefsMinNum: Int = 0
    var prefsMaxnum: Int = 20
    var prefsTriesEnabled: Bool = false
    var prefsMaxTries: Int = 3
    
    @IBAction func closeButton(_ sender: Any) {
        if (!minNumTextField.stringValue.isInt || !maxnumTextField.stringValue.isInt || !triesTextField.stringValue.isInt) {
            let alert = NSAlert()
            alert.messageText = "Error"
            alert.informativeText = "You can only enter (whole) numbers in the text fields."
            alert.alertStyle = .warning
            alert.addButton(withTitle: "OK")
            alert.runModal()
            return
        }
        prefsMinNum = Int(minNumTextField.intValue)
        prefsMaxnum = Int(maxnumTextField.intValue)
        prefsTriesEnabled = triesOn
        prefsMaxTries = Int(minNumTextField.intValue)
        
        print("minNumTextField: \(prefsMinNum) maxnumTextField: \(prefsMaxnum) triesCheckBox: \(prefsTriesEnabled) triesTextField: \(prefsMaxTries)")
        NotificationCenter.default.post(name: Notification.Name("notifyApplyPrefs"),object: nil)
        self.dismiss(self)
    }
}

prefs视图显示为一张纸（我不知道这是否重要）

解决方法

使用instantiateController时，您将创建一个从未使用过的新控制器实例。如果要使用通知传输数据，请在调用self时将post作为对象发送，然后使用它来获取变量。

您还需要更改applyPrefs，使其带有Notification参数，以便您可以使用通知对象。