Question

我有一个应用程序（使用Swift）来计算两个日期之间的差异。它在模拟器上工作正常，但是当我在iOS设备上运行它时，它会崩溃并给出以下错误消息：

在仅变换图层中更改属性masksToBounds将无效 致命错误：

在展开Optional值时意外发现nil （lldb）

在Debug Navigator中，我发现了以下两条错误消息：

如果有人能看到我做错了什么，我将非常感激。谢谢！

这是View Controller代码：

import UIKit

class ViewController: UIViewController {

@IBOutlet weak var startDateTextField: UITextField!
@IBOutlet weak var endDateTextField: UITextField!
@IBOutlet weak var resultNumberOfDays: UILabel!
@IBOutlet weak var resultWeeksAndDays: UILabel!

override func viewDidLoad() {
    super.viewDidLoad()

    self.view.backgroundColor = UIColor(red: 232/255, green: 232/255, blue: 232/255, alpha: 1.0)

    let toolBar = UIToolbar(frame: CGRectMake(0, self.view.frame.size.height/6, self.view.frame.size.width, 40.0))

    toolBar.layer.position = CGPoint(x: self.view.frame.size.width/2, y: self.view.frame.size.height-20.0)

    toolBar.barStyle = UIBarStyle.BlackTranslucent

    toolBar.tintColor = UIColor.whiteColor()

    UIToolbar.appearance().barTintColor = UIColor(red: 179/255, green: 179/255, blue: 179/255, alpha: 1.0)

    let todayBtn = UIBarButtonItem(title: "Today", style: UIBarButtonItemStyle.Plain, target: self, action: "tappedToolBarBtn:")

    let okBarBtn = UIBarButtonItem(title: "Done", style: UIBarButtonItemStyle.Plain, target: self, action: "donePressed:")

    let flexSpace = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.FlexibleSpace, target: self, action: nil)

    let label = UILabel(frame: CGRect(x: 0, y: 0, width: self.view.frame.size.width / 3, height: self.view.frame.size.height))

    label.font = UIFont(name: "Helvetica Neue", size: 13)

    label.backgroundColor = UIColor.clearColor()

    label.textColor = UIColor.whiteColor()

    label.text = "Select a Start Date"

    label.textAlignment = NSTextAlignment.Center

    let textBtn = UIBarButtonItem(customView: label)

    toolBar.setItems([todayBtn,flexSpace,textBtn,flexSpace,okBarBtn], animated: true)

    startDateTextField.inputAccessoryView = toolBar


    let toolBar2 = UIToolbar(frame: CGRectMake(0, self.view.frame.size.height/6, self.view.frame.size.width, 40.0))

    toolBar2.layer.position = CGPoint(x: self.view.frame.size.width/2, y: self.view.frame.size.height-20.0)

    toolBar2.barStyle = UIBarStyle.BlackTranslucent

    toolBar2.tintColor = UIColor.whiteColor()

    UIToolbar.appearance().barTintColor = UIColor(red: 107/255, green: 107/255, blue: 107/255, alpha: 1.0)

    let todayBtn2 = UIBarButtonItem(title: "Today", style: UIBarButtonItemStyle.Plain, target: self, action: "secondTappedToolBarBtn:")

    let okBarBtn2 = UIBarButtonItem(title: "Done", style: UIBarButtonItemStyle.Plain, target: self, action: "secondDonePressed:")

    let flexSpace2 = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.FlexibleSpace, target: self, action: nil)

    let label2 = UILabel(frame: CGRect(x: 0, y: 0, width: self.view.frame.size.width / 3, height: self.view.frame.size.height))

    label2.font = UIFont(name: "Helvetica Neue", size: 13)

    label2.backgroundColor = UIColor.clearColor()

    label2.textColor = UIColor.whiteColor()

    label2.text = "Select an End Date"

    label2.textAlignment = NSTextAlignment.Center

    let textBtn2 = UIBarButtonItem(customView: label2)

    toolBar2.setItems([todayBtn2,flexSpace2,textBtn2,flexSpace2,okBarBtn2], animated: true)

     endDateTextField.inputAccessoryView = toolBar2

    // Do any additional setup after loading the view, typically from a nib.
}

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

func donePressed(sender: UIBarButtonItem) {

    startDateTextField.resignFirstResponder()
}

func secondDonePressed(sender: UIBarButtonItem) {

    endDateTextField.resignFirstResponder()       
}

func tappedToolBarBtn(sender: UIBarButtonItem) {

    let dateformatter = NSDateFormatter()
    dateformatter.dateStyle = NSDateFormatterStyle.MediumStyle
    dateformatter.timeStyle = NSDateFormatterStyle.NoStyle
    startDateTextField.text = dateformatter.stringFromDate(NSDate())
    startDateTextField.resignFirstResponder()
}

func secondTappedToolBarBtn(sender: UIBarButtonItem) {

    let dateformatter = NSDateFormatter()
    dateformatter.dateStyle = NSDateFormatterStyle.MediumStyle
    dateformatter.timeStyle = NSDateFormatterStyle.NoStyle
    endDateTextField.text = dateformatter.stringFromDate(NSDate())
    endDateTextField.resignFirstResponder()
}

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    self.view.endEditing(true)
}

@IBAction func textFieldEditing(sender: UITextField) {
    let datePickerView: UIDatePicker = UIDatePicker()
    datePickerView.datePickerMode = UIDatePickerMode.Date
    sender.inputView = datePickerView
    datePickerView.addTarget(self, action: Selector("datePickerValueChanged:"), forControlEvents: UIControlEvents.ValueChanged)

}

@IBAction func secondTextFieldEditing(sender: UITextField) {
    let datePickerView: UIDatePicker = UIDatePicker()
    datePickerView.datePickerMode = UIDatePickerMode.Date
    sender.inputView = datePickerView
    datePickerView.addTarget(self, action: Selector("secondDatePickerValueChanged:"), forControlEvents: UIControlEvents.ValueChanged)

}

func datePickerValueChanged(sender: UIDatePicker) {
    let dateFormatter = NSDateFormatter()
    dateFormatter.dateStyle = NSDateFormatterStyle.MediumStyle
    dateFormatter.timeStyle = NSDateFormatterStyle.NoStyle
    startDateTextField.text = dateFormatter.stringFromDate(sender.date)

}

func secondDatePickerValueChanged(sender: UIDatePicker) {
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateStyle = NSDateFormatterStyle.MediumStyle
        dateFormatter.timeStyle = NSDateFormatterStyle.NoStyle
        endDateTextField.text = dateFormatter.stringFromDate(sender.date)

}

@IBAction func calculateDays(sender: UIButton) {

    if startDateTextField.text == "" || endDateTextField.text == "" {

        let alert2 = UIAlertController(title: "Oops!", message: "Please Select a Start Date" + "\n" + "and an End Date!", preferredStyle: UIAlertControllerStyle.Alert)
        alert2.addAction(UIAlertAction(title: "Close", style: UIAlertActionStyle.Default, handler: nil))
        self.presentViewController(alert2, animated: true, completion: nil)

    }
    else {

        let start = String(startDateTextField.text!)
        let end = String(endDateTextField.text!)
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = "MM-dd-yyyy"
        let startDate:NSDate = dateFormatter.dateFromString(start)!
        let endDate:NSDate = dateFormatter.dateFromString(end)!
        let calendar = NSCalendar.currentCalendar()
        let components = calendar.components([.Day], fromDate: startDate, toDate: endDate, options: [])
        let secondNewString = "\(components.day) days"
        resultNumberOfDays.text = secondNewString

    }
}


@IBAction func calculateWeeksAndDays(sender: UIButton) {

    if startDateTextField.text == "" || endDateTextField.text == "" {

        let alert2 = UIAlertController(title: "Oops!", message: "Please Select a Start Date" + "\n" + "and an End Date!", preferredStyle: UIAlertControllerStyle.Alert)
        alert2.addAction(UIAlertAction(title: "Close", style: UIAlertActionStyle.Default, handler: nil))
        self.presentViewController(alert2, animated: true, completion: nil)
    }
    else {

    let start = String(startDateTextField.text!)
    let end = String(endDateTextField.text!)
    let dateFormatter = NSDateFormatter()
    dateFormatter.dateFormat = "MM-dd-yyyy"
    let startDate:NSDate = dateFormatter.dateFromString(start)!
    let endDate:NSDate = dateFormatter.dateFromString(end)!
    let calendar = NSCalendar.currentCalendar()
    let components = calendar.components([.Day], fromDate: startDate, toDate: endDate, options: [])
    let days = components.day
    let weeks = components.day / 7
    let weeksanddays = days % 7
    let newString = "\(weeks) weeks + \(weeksanddays) days"
    resultWeeksAndDays.text = newString
}

}

@IBAction func resetLabels(sender: AnyObject) {

    resultNumberOfDays.text = ""
    resultWeeksAndDays.text = ""

}
}

app适用于模拟器，但不适用于ios设备

0 个答案: