Use data from NSUserDefaults in UIPickerView - pickerView stays empty

问题

I tried to set up NSUserDefaults last night but an error keeps occurring:

ViewController3:

save data

  @IBAction func tappedAddButton(sender: AnyObject) {

    var userDefaults:NSUserDefaults = NSUserDefaults.standardUserDefaults()

    var exercisesList:NSMutableArray? = userDefaults.objectForKey("exercisesList") as? NSMutableArray

    var dataSet:NSMutableDictionary = NSMutableDictionary()
    dataSet.setObject(textField.text, forKey: "exercises")

    if ((exercisesList) != nil){
        var newMutableList:NSMutableArray = NSMutableArray();

        for dict:AnyObject in exercisesList!{
            newMutableList.addObject(dict as NSDictionary)
        }

        userDefaults.removeObjectForKey("exercisesList")
        newMutableList.addObject(dataSet)
        userDefaults.setObject(newMutableList, forKey: "exercisesList")

    }else{
        userDefaults.removeObjectForKey("exercisesList")
        exercisesList = NSMutableArray()
        exercisesList!.addObject(dataSet)
        userDefaults.setObject(exercisesList, forKey: "exercisesList")
    }

    userDefaults.synchronize()

    self.view.endEditing(true)
    textField.text = ""

}

ViewController1:

load data

 var exercises:NSMutableArray = NSMutableArray();

...

    override func viewDidAppear(animated: Bool) {

    var userDefaults:NSUserDefaults = NSUserDefaults.standardUserDefaults()

    var exercisesListFromUserDefaults:NSMutableArray? = userDefaults.objectForKey("exercisesList") as? NSMutableArray

    if ((exercisesListFromUserDefaults) != nil){
        exercises = exercisesListFromUserDefaults!
    }

}

While adding some data to the variable "exercises", the pickerView stays empty.

回答1:

You are setting userDefaults with the key "exercisesList" but attempting to get the data back with a different key ("itemList")

来源：https://stackoverflow.com/questions/28169201/use-data-from-nsuserdefaults-in-uipickerview-pickerview-stays-empty