How can I get events to my (sub) UIView? - ios

Question

I'm new to Swift and have a hard time understand the event flow. The code below can be run directly in an xcode playground. I have a white UIView in the background. This view has a brown button and a red view as sub-views. Click on them and the events are logged in the controller, just as expected.
But the controller of this white view also adds another view, that has it's own controller class (SubviewController). SubviewController is green and has a blue subview with a black button. Question is... why don't I get any logs from the green, blue and black views/buttons?
import Foundation
import UIKit
import PlaygroundSupport
class TestViewController : UIViewController {
let playButton: UIButton = {
let playButton = UIButton(frame: CGRect(x: 155, y: 135, width: 160, height: 40))
playButton.setTitle("BROWN BUTTON", for: .normal)
playButton.backgroundColor = UIColor.brown
return playButton
}()
override func loadView() {
let viewWhite = UIView()
viewWhite.backgroundColor = UIColor.white
let viewRed = UIView()
viewRed.backgroundColor = UIColor.red
viewRed.frame = CGRect(x: 20, y: 20, width: 40, height: 10)
viewRed.clipsToBounds = true
let recognizer2 = UITapGestureRecognizer(target: self, action: #selector (self.handleTapRed(_:)))
viewRed.addGestureRecognizer(recognizer2)
let recognizer = UITapGestureRecognizer(target: self, action: #selector (self.handleTap(_:)))
viewWhite.addGestureRecognizer(recognizer)
playButton.addTarget(self, action: #selector (self.action) , for: .touchUpInside)
let catList = SubviewController()
viewWhite.addSubview(catList.view)
viewWhite.addSubview(playButton)
viewWhite.addSubview(viewRed)
self.view = viewWhite
}
func action() {
print("Brown button tapped")
}
func handleTap(_ sender:UITapGestureRecognizer){
print("WHITE VIEW (background view) TAPPED")
}
func handleTapRed(_ sender:UITapGestureRecognizer){
print("RED VIEW TAPPED")
}
}
class SubviewController: UIViewController {
let buttonBlack: UIButton = {
let button = UIButton(frame: CGRect(x: 40, y: 10, width: 170, height: 20))
button.backgroundColor = UIColor.black
button.setTitle("BLACK BUTTON", for: .normal)
return button
}()
let viewBlue: UIView = {
let v = UIView()
v.backgroundColor = UIColor.blue
v.frame = CGRect(x: 20, y: 40, width: 240, height: 60)
v.clipsToBounds = true
return v
}()
override func loadView() {
super.loadView()
self.view.backgroundColor = UIColor.green
buttonBlack.addTarget(self, action: #selector (self.blackKlick) , for: .touchUpInside)
self.view.addSubview(viewBlue)
self.view.frame = CGRect(x: 0, y: 40, width: 240, height: 60)
self.view.clipsToBounds = true
self.view.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector (self.handleTapGreen(_:))))
viewBlue.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector (self.handleTapBlue(_:))))
viewBlue.addSubview(buttonBlack)
}
func blackKlick() {
print("Black button tapped")
}
func handleTapBlue(_ sender:UITapGestureRecognizer){
print("BLUE VIEW TAPPED")
}
func handleTapGreen(_ sender:UITapGestureRecognizer){
print("GREEN VIEW TAPPED")
}
}
PlaygroundPage.current.liveView = TestViewController()
Thanks for any help!

Answer 1

This line in your current code:
let catList = SubviewController()
creates a local instance of SubvieController. As soon as you exit the loadView() func, that instance is gone.
So, you need a class-level variable to keep that instance around. Add this line:
class TestViewController : UIViewController {
var catList: SubviewController!
and then remove the let from the instantiation line in loadView():
catList = SubviewController()