pickerView.swift

//: A UIKit based Playground for presenting user interface
  
import UIKit
import PlaygroundSupport

class MyViewController : UIViewController {
    var data = [
        "AB",
        "BC",
        "CD",
        "DE",
        "EF"
    ]
    override func loadView() {
        let view = UIView()
        view.backgroundColor = .white
        
        let label = UILabel()
        label.text = "Hello ~ PickerView"
        label.textColor = .black
        label.textAlignment = .center
        
        view.addSubview(label)
        label.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            label.topAnchor.constraint(equalTo: view.topAnchor, constant: 40),
            label.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            label.heightAnchor.constraint(equalToConstant: 30)
        ])
        
        let pv = UIPickerView(frame: CGRect(x: 0, y: 0, width: 80, height: 80))
        pv.delegate = self
        pv.dataSource = self
        pv.layer.borderWidth = 1
        pv.layer.borderColor = UIColor.black.cgColor
        
        view.addSubview(pv)
        pv.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            pv.topAnchor.constraint(equalTo: label.bottomAnchor, constant: 20),
            pv.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            pv.widthAnchor.constraint(equalToConstant: 80),
            pv.heightAnchor.constraint(equalToConstant: 80)
        ])
        
        self.view = view
        print("--")
        
        self.view = view
    }
}
extension MyViewController: UIPickerViewDataSource, UIPickerViewDelegate {
    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 1
    }
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        return self.data.count
    }
    func pickerView(_ pickerView: UIPickerView, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString? {
        return NSAttributedString(string: self.data[row], attributes: [.foregroundColor:UIColor.red])
    }
    
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()