iOS Swift difference between UITextField and UITextView

Either one can be used for getting user input but a general thumb rule to follow is

• For entering a single line of text use UITextField. 
• For displaying or entering one or more lines of text use UITextView.

import UIKit

class ViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.navigationItem.title = "Main View"
        
        addUIViews()
       
    }
    
    func addUIViews(){
        
        let myTextField = UITextField()
        myTextField.translatesAutoresizingMaskIntoConstraints = false
        self.view.addSubview(myTextField)
        
        let myTextView = UITextView()
        myTextView.translatesAutoresizingMaskIntoConstraints = false
        self.view.addSubview(myTextView)
        
        let views = [
            "view" : view,
            "textField" : myTextField,
            "textView" : myTextView
            ]
        
        var allConstraints: [NSLayoutConstraint] = []
        allConstraints += NSLayoutConstraint.constraints(withVisualFormat: "V:|-20-[textField(50)]-[textView]-|",
                            options: [], metrics: nil, views: views as [String : Any])
        allConstraints += NSLayoutConstraint.constraints(withVisualFormat: "H:|-[textField(200)]-|",
                            options: [], metrics: nil, views: views as [String : Any])
        allConstraints += NSLayoutConstraint.constraints(withVisualFormat: "H:|-[textView(200)]-|",
                            options: [], metrics: nil, views: views as [String : Any])
        NSLayoutConstraint.activate(allConstraints)
        
        myTextField.layer.borderWidth = 1.0
        myTextField.layer.cornerRadius = 5.0
        myTextField.font = .systemFont(ofSize: 24)
        
        myTextView.layer.borderWidth = 1.0
        myTextView.layer.cornerRadius = 5.0
        myTextView.font = .systemFont(ofSize: 24)
       
    }
    
    
}