@IBOutlet weak var modelPicker: UIPickerView!
@IBOutlet weak var makePicker: UIPickerView!
@IBOutlet weak var yearPicker: UIPickerView!

var makeRow = 0
var modelRow = 0
var yearRow = 0

var listOfMakes: [String] = [String]()
var listOfModels: [String] = [String]()
var listOfYears: [String] = [String]()
var carlist: Dictionary <String, Dictionary<String,Dictionary<String,String>>> = Dictionary()

override func viewDidLoad() {
    super.viewDidLoad()

    modelPicker.delegate = self
    modelPicker.dataSource = self
    makePicker.delegate = self
    makePicker.dataSource = self
    yearPicker.delegate = self
    yearPicker.dataSource = self

    self.listOfMakes = Array(carDictionary.keys)
    let firstCar = listOfMakes[0]
    let modelsDictionary = carlist[firstCar]! as  Dictionary<String, Dictionary<String, String>>
    self.listOfModels = Array(modelsDictionary.keys).sorted()
    let firstModel = listOfModels[0]
    let yearsDictionary = modelsDictionary[firstModel]! as Dictionary<String, String>
    self.listOfYears = Array(yearsDictionary.keys).sorted()
}

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


func setModelsList(make: String) {
    let modelsDictionary = carlist[make]! as  Dictionary<String, Dictionary<String, String>>
    self.listOfModels = Array(modelsDictionary.keys).sorted()
}

func setYearsList(make: String, model: String) {
    let modelsDictionary = carlist[make]! as  Dictionary<String, Dictionary<String, String>>
    let modelsList = Array(modelsDictionary.keys)
    let yearsDictionary = modelsDictionary[model]! as Dictionary<String, String>
    self.listOfYears = Array(yearsDictionary.keys).sorted()
}


func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {

    if pickerView == makePicker {
        return listOfMakes.count
    }
    else if pickerView == modelPicker {
        return listOfModels.count
    }
    else {
        return listOfYears.count
    }
}

func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {

    if pickerView == makePicker {
        return listOfMakes[row]
    }
    else if pickerView == modelPicker {
        return listOfModels[row]
    }
    else {
        return listOfYears[row]
    }
}


func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    if pickerView == makePicker {
        makeRow = row
        setModelsList(make: listOfMakes[makeRow])
        setYearsList(make: listOfMakes[makeRow], model: listOfModels[0])
        modelPicker.selectRow(0, inComponent: 0, animated: true)
        yearPicker.selectRow(0, inComponent: 0, animated: true)
        self.modelPicker.reloadAllComponents()
        self.yearPicker.reloadAllComponents()
    }
    else if pickerView == modelPicker {
        modelRow = row
        setYearsList(make: listOfMakes[makeRow], model: listOfModels[modelRow])
        yearPicker.selectRow(0, inComponent: 0, animated: true)
        self.modelPicker.reloadAllComponents()
        self.yearPicker.reloadAllComponents()
    }
    else {
        //do anything you want once you have chosen a specific year.
    }
}