在Swift的另一个班级中声明自己

Question

public class CustomSelectFields: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {
    let cities = ["city1", "city2"]
    let selectiveTextField = UITextField()
    let pickerView = UIPickerView()


    //normally it will get array of cities and frame position

    public func CreateCustomSelectField() -> UITextField {

        selectiveTextField.frame = CGRect(x: ScreenSize.width * 0.1, y: ScreenSize.height * 0.4, width: ScreenSize.width * 0.8, height: ScreenSize.height * 0.1)
        selectiveTextField.placeholder = "Placehoder"
        selectiveTextField.inputView = pickerView

        //should i declare delegates and datasoruce here?
        pickerView.delegate = self
        pickerView.dataSource = self

        return selectiveTextField
    }

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

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

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

    public func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        selectiveTextField.text = cities[row]
        selectiveTextField.resignFirstResponder()
    }

}

I'm trying to create a custom UIPickerView and i want it to use in another classes. When I declare it's delegate and datasource in the same class, data are not showing up.

Also I try to declare in the class which is i use for viewController Like this:

let textField = customElements.CreateCustomSelectField()
customElements.pickerView.delegate = ??
customElements.pickerView.dataSource = ??

self.view.addSubview(textField)

How can I accomplish this delegate & datasource issue?

Answer 1

Your design and your code are garbled. You've defined a class, CustomSelectFields , that looks like you want it to manage a text field and a picker view. Then you have a method, CreateCustomSelectField , that sounds like a convenience initializer for your CustomSelectFields class. However, it's actually an instance method that configures and returns a UITextField that belongs to the CustomSelectFields class.

Your CustomSelectFields class conforms to the UIPickerViewDelegate and UIPickerViewDataSource protocols, which suggests that you intend it to act as the delegate for the picker view. If that's the case, the CustomSelectFields class should have an initializer that creates the picker view and text field and configures them initially.

Something like this:

public class CustomSelectFields: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {

  let cities = ["city1", "city2"]
  let selectiveTextField: UITextField
  let pickerView: UIPickerView

  init() {
    selectiveTextField = UITextField()
    selectiveTextField.frame = CGRect(x: ScreenSize.width * 0.1, 
      y: ScreenSize.height * 0.4, 
      width: ScreenSize.width * 0.8, 
      height: ScreenSize.height * 0.1)
    selectiveTextField.placeholder = "Placehoder" //Hodor! HODOR!
    selectiveTextField.inputView = pickerView

    pickerView.delegate = self
    pickerView.dataSource = self

    pickerView = UIPickerView()
    pickerView.delegate = self
    pickerView.dataSource = self
  }
}

But even still, having a class that creates and configures view objects - but doesn't display or manage them - is kind of odd.