Initialization of property with closure

Question

I studied ARC and strong reference loops and came across this code:

class TestClass: UIView {
  let button: UIButton = {
    let view = UIButton()
    view.frame = CGRect(x: 50, y: 50, width: 200, height: 200)
    view.backgroundColor = .blue
    view.translatesAutoresizingMaskIntoConstraints = false
    view.setTitle("Button", for: .normal)
    view.addTarget(self, action: #selector(buttonClicked), for: .touchUpInside)
    return view
  }()

  @objc private func buttonClicked() {
    print("Clicked")
  }

  override init(frame: CGRect) {
    super.init(frame: frame)
    print("Object of TestClass initialized")
  }

  required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }

  deinit {
    print("Object of TestClass deinitialized")
  }
}

The reference selfto the addTargetmethod inside the shutter does not seem to create a strong reference loop.

Can someone explain why?

Also, I noticed that if I remove inheritance from UIViewthe compiler starts to complain Use of unresolved identifier 'self'.

Can someone explain this also, why is this happening in this case and not in the first?

Answer 1

This is not a conservation cycle, because self- this is not what you think:

, self :

(TestClass) -> () -> TestClass

, , static -like, , . .

addTarget Any? , , , NSObject.

- . , , - : , - :