Adding a custom UIViewcontroller to subview programmically but getting an error message "Cannot convert value of type..."



I am trying to add a custom UIViewController class (UIPickerView) to my main ViewController programmatically in Swift (without using a storyboard) but I get the following error message...

"Cannot convert value of type 'HabitViewViewController' to expected argument type 'UIView'

Any ideas would be most welcomed ;-)

Custom UIPicker class:

    import UIKit

    class HabitViewController: UIViewController,UIPickerViewDataSource,UIPickerViewDelegate  {

        @IBOutlet weak var myPicker: UIPickerView!
        @IBOutlet weak var myLabel: UILabel!
        let pickerData = ["Mozzarella","Gorgonzola","Provolone","Brie","Maytag Blue","Sharp Cheddar","Monterrey Jack","Stilton","Gouda","Goat Cheese", "Asiago"]

        override func viewDidLoad() {
            myPicker.delegate = self
            myPicker.dataSource = self

        //MARK: - Delegates and data sources
        //MARK: Data Sources

        func numberOfComponents(in pickerView: UIPickerView) -> Int {
            return 1

        func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
            return pickerData.count

        //MARK: Delegates

        func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
            return pickerData[row]

        func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
            myLabel.text = pickerData[row]

        func pickerView(_ pickerView: UIPickerView, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString? {
            let titleData = pickerData[row]
            let myTitle = NSAttributedString(string: titleData, attributes: [NSFontAttributeName:UIFont(name: "Georgia", size: 26.0)!,])
            return myTitle

        func pickerView(_ pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusing view: UIView?) -> UIView {
            var pickerLabel = view as! UILabel!
            if view == nil {  //if no label there yet
                pickerLabel = UILabel()
                //color the label's background
                let hue = CGFloat(row)/CGFloat(pickerData.count)
                pickerLabel?.backgroundColor = UIColor(hue: hue, saturation: 1.0, brightness: 1.0, alpha: 1.0)
            let titleData = pickerData[row]
            let myTitle = NSAttributedString(string: titleData, attributes: [NSFontAttributeName:UIFont(name: "Georgia", size: 26.0)!,])
            pickerLabel!.attributedText = myTitle
            pickerLabel!.textAlignment = .center

            return pickerLabel!



Main UIView

    import UIKit

    // Activity Month view Class (Type BaseCell - cleaner)
    class PlantCell: BaseCell {

        // UIpicker for habit
        let habitPicker: HabitViewController = {

            let habit = HabitViewController()
            return habit

        // Overrided as it uses the baseCell superclass
        override func setupViews() {

            // Add subviews

            // Horizontal constraints
            addConstraintsWithFormat(format: "H:|-[v0]-|", views: habitPicker)

            // Vertical constraints
            addConstraintsWithFormat(format: "V:|-250-[v0(20)]", views: habitPicker)




    import UIKit

    // Superclass to initalise all base UICollectionView cells
    class BaseCell: UICollectionViewCell {
        override init(frame: CGRect) {
            // When dequeueReusableCell is called this init method is called if it needs a new cell
            super.init(frame: frame)

        func setupViews() {


        required init?(coder aDecoder: NSCoder) {
            fatalError("init(coder:) has not been implemented")

1 Answer: 


The expected argument is UIView, so you can simple fix it by addSubview(habitPicker.view). And remember to adjust habitPicker.view frame size suitable.