Swift inheritance 携带约束

Question

In my swift code below I am attempting to use inheritance. When I go to class middle the constraints on the initial view controller are still being applied. Even though in middle class I attempt to attach new constraints to right button they are not being applied. You can see what is going wrong in the photo below.

import UIKit

class ViewController: UIViewController {
    
    var right = UIButton()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        [right].forEach{
            $0.translatesAutoresizingMaskIntoConstraints = false
            view.addSubview($0)
            $0.backgroundColor = UIColor(
                red: .random(in: 0.0...1),
                green: .random(in: 0.9...1),
                blue: .random(in: 0.7...1),
                alpha: 1
            )
        }
        
        NSLayoutConstraint.activate([

            right.bottomAnchor.constraint(equalTo: view.bottomAnchor),
            right.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            right.heightAnchor.constraint(equalTo: view.heightAnchor,multiplier: 0.1),
            right.widthAnchor.constraint(equalTo: view.widthAnchor,multiplier: 1),
            
            
        ])
        right.setTitle(">", for: .normal)
        right.addTarget(self, action: #selector(nexte), for: .touchDown)
    }
    
    
    @objc func nexte(){
        
        let vc = middle()
        vc.modalPresentationStyle = .overCurrentContext // actually .fullScreen would be better
        self.present(vc, animated: true)
        
    }
    
}


class middle : ViewController{
    
    var leftbtn = UIButton()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        [leftbtn].forEach{
            $0.translatesAutoresizingMaskIntoConstraints = false
            view.addSubview($0)
            $0.backgroundColor = UIColor(
                red: .random(in: 0.0...1),
                green: .random(in: 0.9...1),
                blue: .random(in: 0.7...1),
                alpha: 1
            )
            
        }
        
        NSLayoutConstraint.activate([
            
            leftbtn.bottomAnchor.constraint(equalTo: view.bottomAnchor),
            leftbtn.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            leftbtn.heightAnchor.constraint(equalTo: view.heightAnchor,multiplier: 0.1),
            leftbtn.widthAnchor.constraint(equalTo: view.widthAnchor,multiplier: 0.5 ),
            
            right.bottomAnchor.constraint(equalTo: view.bottomAnchor),
            right.leadingAnchor.constraint(equalTo: leftbtn.trailingAnchor),
            right.heightAnchor.constraint(equalTo: view.heightAnchor,multiplier: 0.1),
            right.widthAnchor.constraint(equalTo: view.widthAnchor,multiplier: 0.5 ),
            
        ])
        
    }
}

Answer 1

You are saying super.viewDidLoad() in Middle. super is ViewController so ViewController's viewDidLoad is executed too. Thus "When I go to class middle the constraints on the initial view controller are still being applied".

You should rethink your whole architecture here.