Question

是什么导致这种情况发生？这个错误的两个实例位于我的视图控制器的最底部，其中的行以“userDefaults”开头。这是我的代码

import UIKit

class SecondViewController : UIViewController,UITextFieldDelegate {

@IBOutlet weak var dateLabel: UILabel!
@IBOutlet weak var datePicker: UIDatePicker!

var aRandomDate = NSDate()


override func viewDidLoad() {
    super.viewDidLoad()

    datePicker.addTarget(self, action: Selector("datePickerChanged:"), forControlEvents: UIControlEvents.ValueChanged)
}

func datePickerChanged(datePicker:UIDatePicker) {
    var dateFormatter = NSDateFormatter()

    dateFormatter.dateStyle = NSDateFormatterStyle.LongStyle

    var strDate = dateFormatter.stringFromDate(datePicker.date)
    dateLabel.text = strDate
}

func textFieldShouldReturn(textField: UITextField) -> Bool {
    textField.resignFirstResponder()

    return true;
}

@IBAction func Save(sender: UIButton) {
    var t = EventSaver(pEventName: "Drinking Coffee", pEventDate: aRandomDate )

    let encodedEventName = NSKeyedArchiver.archivedDataWithRootObject(t.EventName)
    let encodedEventDate = NSKeyedArchiver.archivedDataWithRootObject(t.EventDate)

    var encodedArray: [NSData] = [encodedEventName,]


    userDefaults.setObject(encodedArray, forKey: "Event")
    userDefaults.synchronize()


    println("saved")
}
}

Answer 1

似乎你还没有声明常量userDefaults。在userDefaults中设置encodedArray对象之前添加以下行：

let userDefaults = NSUserDefaults.standardUserDefaults()

Answer 2

像这样：

@IBAction func Save(sender: UIButton) {
var t = EventSaver(pEventName: "Drinking Coffee", pEventDate: aRandomDate )

var userDefaults = NSUserDefaults.standardUserDefaults() 

let encodedEventName = NSKeyedArchiver.archivedDataWithRootObject(t.EventName)
let encodedEventDate = NSKeyedArchiver.archivedDataWithRootObject(t.EventDate)

var encodedArray: [NSData] = [encodedEventName,]


userDefaults.setObject(encodedArray, forKey: "Event")
userDefaults.synchronize()


println("saved")


}

使用未解析的标识符userDefaults

2 个答案: