How to make this UIButton's action operate correctly? - swift

Question

Every time I run this swift playground (on Xcode), I get an error on the last line saying:
'PlaygroundView' cannot be constructed because it has no accessible initialisers.
I also have another error on line 4 saying:
class 'PlaygroundView' has no initializers.
import UIKit
import PlaygroundSupport
class PlaygroundView:UIViewController {
var introImage:UIImageView
var introButton:UIButton
override func loadView() {
print("workspace started running.")
//Main Constant and Variable Declarations/General Setup
let mainView = UIView()
//Main View Modifications & styling
mainView.backgroundColor = UIColor.init(colorLiteralRed: 250, green: 250, blue: 250, alpha: 1)
func addItem(item: UIView) {
mainView.addSubview(item)
}
//Sub-Element Constant and Variable Declarations
introImage = UIImageView(frame: CGRect(x: 87.5, y: -300, width: 200, height: 200))
introImage.layer.borderColor = UIColor.black.cgColor
introImage.layer.borderWidth = 4
introImage.alpha = 0
introImage.transform = CGAffineTransform(rotationAngle: -90.0 * 3.14/180.0)
introImage.image = UIImage(named: "profile_pic.png")
introImage.image?.accessibilityFrame = introImage.frame
introImage.layer.cornerRadius = 100
addItem(item: introImage)
introButton = UIButton(frame: CGRect(x: 87.5, y: 900, width: 200, height: 30))
introButton.alpha = 0
introButton.setTitle("Tap to meet me", for: .normal)
introButton.titleLabel?.font = UIFont(name: "Avenir Book", size: 20)
introButton.backgroundColor = UIColor.black
introButton.layer.cornerRadius = 15
introButton.layer.borderWidth = 5
addItem(item: introButton)
introButton.addTarget(self, action: #selector(self.introButtonAction), for: .touchDown)
UIView.animate(withDuration: 1.5, delay: 1, options: .curveEaseInOut, animations: {
self.introImage.frame = CGRect(x: 87.5, y: 175, width: 200, height: 200)
self.introButton.frame = CGRect(x: 87.5, y: 400, width: 200, height: 30)
self.introImage.transform = CGAffineTransform(rotationAngle: 0.0 * 3.14/180.0)
self.introImage.alpha = 1
self.introButton.alpha = 1
}) { (mainAnimationComped) in
if mainAnimationComped == true {
print("introduction animation comped.")
}
}
}
//User Interface Actions
func introButtonAction() {
print("user interacted with user interface")
}
}
PlaygroundPage.current.liveView = PlaygroundView()
How would I fix this problem?

Answer 1

That's because in Swift, you need to initialize variables before use them in the code. On the other hand, since in this case you set them explicitly in your function, you might declare them as implicitly unwrapped optionals
var introImage:UIImageView!
var introButton:UIButton!
and this should work without changing anything else in your code

Answer 2

Add ? after introImage and introButton
var introImage:UIImageView?
var introButton:UIButton?