swift - 实例化 View Controller 时出错

Question

当我尝试使用下面的代码(在 viewDidLoad 部分)实例化我的 ViewController 时，在 self.present 行上运行应用程序时，我得到一个 Thread 1: EXC_BAD_ACCESS 。 (我是编码初学者)

编辑:所以我在这里提供了完整的代码，看看哪里出了问题。我现在将代码转移到第二个 View Controller 的 viewDidLoad 中。现在应用程序启动了，但是当我按下“enter”按钮时，我收到“Thread 1: Fatal error: Unexpectedlyfound nil while unwrapping anOptional value”错误..

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var progressBarView: ProgressBarView!
    
    @IBOutlet weak var progressBarView1: ProgressBarView1!
    
    
    override func viewDidLoad() {
        super.viewDidLoad()
// updaten van de progressbar
        progressBarView.progress = CGFloat(percProgress())
        progressBarView1.progress = CGFloat(0.5)

// een constante maken die de daystogocalc Int van de berekening verderop in een String cast
        let daysToGoCalcString = String(daysToGoCalc())

// updaten van het label daysToGo
        daysToGo.text = "Still \(daysToGoCalcString) days to go"

// updaten van het label textPercentage
        let textPercentage = NSString(format: "%.0f", (percProgress() * 100))
        percentageDays.text = String(textPercentage) + "%"
    
    }
    

        

    
        
    @IBOutlet weak var daysToGo: UILabel!
    
    @IBOutlet weak var percentageDays: UILabel!
    
    @IBOutlet weak var firstGoalLabel: UILabel!
    
    
    @IBAction func unwindToGoals(unwindSegue: UIStoryboardSegue) {
        
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    // Automatische datumberekening
    let today = Date()
    let calendar = Calendar.current
    // Dagnummer van het jaar
    var todayNumber: Int {
        get {
            return calendar.ordinality(of: .day, in: .year, for: today)!
        }
    }
    // FLOAT MAKER: onderstaande maakt een Float van het dagnummer (nodig voor de Progress Bar uiteindelijk)
    var todayFloat: Float {
        get {
            return Float(todayNumber)
        }
    }
    // KWARTAAL PROGRESSIE: deze functie checkt eerst in welk kwartaal je zit, en vervolgens de voortgang in dat kwartaal in een float
    func percProgress() -> Float {
        
        if todayNumber < 91 {
            return todayFloat / 90
        }
        else if todayNumber < 182 {
            return (todayFloat - 90) / 91
        }
        else if todayNumber < 274 {
            return (todayFloat - 181) / 92
        }
        else {
            return (todayFloat - 273) / 92
        }
    }
    
    // Bereken aantal dagen te gaan in kwartaal
    func daysToGoCalc() -> Int {
        
        if todayNumber < 91 {
            return 90 - todayNumber
        }
        else if todayNumber < 182 {
            return 181 - todayNumber
        }
        else if todayNumber < 274 {
            return 273 - todayNumber
        }
        else {
            return 365 - todayNumber
        }
    }
    

}




// SECOND VIEW CONTROLLER

class SecondViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
    
        firstGoaltext.delegate = self
        firstGoalStart.delegate = self
        firstGoalEnd.delegate = self
        
        secondGoaltext.delegate = self
        secondGoalStart.delegate = self
        secondGoalEnd.delegate = self
        
        thirdGoaltext.delegate = self
        thirdGoalStart.delegate = self
        thirdGoalEnd.delegate = self
        
        fourthGoaltext.delegate = self
        fourthGoalStart.delegate = self
        fourthGoalEnd.delegate = self
        
        fifthGoaltext.delegate = self
        fifthGoalStart.delegate = self
        fifthGoalEnd.delegate = self
    
        // INSTANTIATE VIEWCONTROLLER
        let storyboard1 = UIStoryboard(name: "Main", bundle: nil)
        var firstController: UIViewController {
            get {
                return storyboard1.instantiateViewController(withIdentifier: "myViewControllerIdentifier")
            }
        }
        
        self.present(firstController, animated: true, completion: nil)
        
    }



    @IBOutlet weak var firstGoaltext: UITextField!
    @IBOutlet weak var firstGoalStart: UITextField!
    @IBOutlet weak var firstGoalEnd: UITextField!
    
    @IBOutlet weak var secondGoaltext: UITextField!
    @IBOutlet weak var secondGoalStart: UITextField!
    @IBOutlet weak var secondGoalEnd: UITextField!
    
    @IBOutlet weak var thirdGoaltext: UITextField!
    @IBOutlet weak var thirdGoalStart: UITextField!
    @IBOutlet weak var thirdGoalEnd: UITextField!
    
    @IBOutlet weak var fourthGoaltext: UITextField!
    @IBOutlet weak var fourthGoalStart: UITextField!
    @IBOutlet weak var fourthGoalEnd: UITextField!
    
    @IBOutlet weak var fifthGoaltext: UITextField!
    @IBOutlet weak var fifthGoalStart: UITextField!
    @IBOutlet weak var fifthGoalEnd: UITextField!
    
    @IBAction func enter(_ sender: Any!) {
        
        let vc1 = ViewController()
        vc1.firstGoalLabel.text = firstGoaltext.text
    }
    
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        firstGoalStart.resignFirstResponder()
    }
    
}



extension SecondViewController : UITextFieldDelegate {
    
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        textField.resignFirstResponder()
        return true
    }
    
}

我在这里做错了什么？

Answer 1

尝试在“viewDidAppear”而不是“viewDidLoad”中运行代码片段