swift playground UITextField spawns keyboard that is too big

Question

Swift in playground on Mac OS. When the user clicks in a UItextfield, a keyboard spawns but it is very large compared to the view and only the first few keys are available.

minimal example:

import UIKit
import PlaygroundSupport

class TesterViewController : UIViewController {
var testTextField : UITextField!
override func loadView() {
    let view = UIView()
    view.backgroundColor = .white

    testTextField = UITextField()
    testTextField.borderStyle = .roundedRect
    testTextField.text = ""
    view.addSubview(testTextField)
    testTextField.translatesAutoresizingMaskIntoConstraints = false

    NSLayoutConstraint.activate([
        testTextField.topAnchor.constraint(equalTo: view.topAnchor, constant: 20),
        testTextField.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20),
        ])

    self.view = view
    }
}
PlaygroundPage.current.liveView = TesterViewController()

screenshot

Answer 1

System keyboard is presented according to the key window size and in the case of a playground simulator the size is 768x1024. It looks like it is a bug.

A solution which works:

Instead of passing a view controller one should pass a window with a custom size.

let window = UIWindow(frame: CGRect(x: 0,
                                    y: 0,
                                    width: 768,
                                    height: 1024))
let viewController = MyViewController()
window.rootViewController = viewController
window.makeKeyAndVisible()

PlaygroundPage.current.liveView = window

Works in Xcode 11 and above (latest tested version Xcode 12.2)

Edited

I have checked the answer which suggests to use "vc.preferredContentSize" but it doesn't work for me. Tested in Xcode 12.2

let vc = TextFieldViewController()
vc.preferredContentSize = CGSize(width: 768,height: 1024)
PlaygroundPage.current.liveView = vc

Answer 2

I face the same issue. It seems as if Playground has a hard-coded screen size of 768x1024 (run UIScreen.main.bounds in the Playground) and shows the keyboard according to this size, independently of the live view's actual size.

The best workaround I came up with is to increase the size of the view controller so that it matches the keyboard:

let vc = TesterViewController()
vc.preferredContentSize = vc.view.frame.size // or a custom CGSize
PlaygroundPage.current.liveView = vc

Of course this makes the view larger than you might want it to be, so I only use this workaround when I really have to access the on-screen keyboard for testing.