Back button doesn't work when changing background color

Question

I have an app which displays a list of fruits. When you click on one of them, a view pops up with all the information and nutritional values within that fruit. If the fruit I click on contains more than 10 in sugar, the background should repeat between red and white. My problem is that I have a back button (Tilbake) which works on every view except for the ones that have the animated background color with over 10 in sugar. The ability to swipe the view down stops working too. It seems to be some kind of layer which is on top of the screen stopping me from actually touching the screen. How do I solve this?

import UIKit

class FruitDetailVC: UIViewController{
    var fruit: Fruit?
    
    var safeArea: UILayoutGuide!
    let nameLabel = UILabel()
    let genusLabel = UILabel()
    let familyLabel = UILabel()
    let orderLabel = UILabel()
    let idLabel = UILabel()
    let carbLabel = UILabel()
    let proteinLabel = UILabel()
    let fatLabel = UILabel()
    let caloriesLabel = UILabel()
    let sugarLabel = UILabel()
    let dividerLabel = UILabel()
    let sugarWarningLabel = UILabel()
    let dismissButton = UIButton()
    
    
    override func viewDidLoad() {
        super.viewDidLoad()
        setupdata()
        setupLabel()
        setupDismissButton()
        safeArea = view.layoutMarginsGuide
        view.backgroundColor = .white
        if (fruit?.nutritions.sugar)! > 10{
            sugarWarningLabel.text = "This contains over 10 of sugar!!!"
            animatedBackground()
        }
    }
    
    func animatedBackground(){
        UIView.animate(withDuration: 1.0, delay: 0.0, options:[.repeat, .autoreverse], animations: {
            self.view.backgroundColor = UIColor(red: 255/255, green: 0/255, blue: 0/255, alpha: 1.0)
        }, completion:{
            (completed : Bool) -> Void in
            UIView.animate(withDuration: 1.0, delay: 0.0, options:[.repeat, .autoreverse], animations: {
                self.view.backgroundColor = UIColor(red: 255/255, green: 255/255, blue: 255/255, alpha: 1.0)
               }, completion:nil)
        })
       
    }
    
    
    func setupLabel(){
        view.addSubview(nameLabel)
        view.addSubview(genusLabel)
        view.addSubview(familyLabel)
        view.addSubview(orderLabel)
        view.addSubview(idLabel)
        view.addSubview(carbLabel)
        view.addSubview(proteinLabel)
        view.addSubview(fatLabel)
        view.addSubview(caloriesLabel)
        view.addSubview(sugarLabel)
        view.addSubview(dividerLabel)
        view.addSubview(sugarWarningLabel)
        
        //General infromation about selected fruit
        nameLabel.translatesAutoresizingMaskIntoConstraints = false
        nameLabel.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        nameLabel.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        nameLabel.font = UIFont(name: "Verdana-Bold", size: 16)
        
        genusLabel.translatesAutoresizingMaskIntoConstraints = false
        genusLabel.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        genusLabel.topAnchor.constraint(equalTo: nameLabel.bottomAnchor).isActive = true
        genusLabel.font = UIFont(name: "Verdana", size: 14)
        
        familyLabel.translatesAutoresizingMaskIntoConstraints = false
        familyLabel.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        familyLabel.topAnchor.constraint(equalTo: genusLabel.bottomAnchor).isActive = true
        familyLabel.font = UIFont(name: "Verdana", size: 14)
        
        orderLabel.translatesAutoresizingMaskIntoConstraints = false
        orderLabel.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        orderLabel.topAnchor.constraint(equalTo: familyLabel.bottomAnchor).isActive = true
        orderLabel.font = UIFont(name: "Verdana", size: 14)
        
        idLabel.translatesAutoresizingMaskIntoConstraints = false
        idLabel.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        idLabel.topAnchor.constraint(equalTo: orderLabel.bottomAnchor).isActive = true
        idLabel.font = UIFont(name: "Verdana", size: 14)
        
        //Nutrition information divider
        dividerLabel.translatesAutoresizingMaskIntoConstraints = false
        dividerLabel.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        dividerLabel.topAnchor.constraint(equalTo: idLabel.bottomAnchor).isActive = true
        dividerLabel.font = UIFont(name: "Verdana-Bold", size: 16)
        
        //Nutrition information
        carbLabel.translatesAutoresizingMaskIntoConstraints = false
        carbLabel.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        carbLabel.topAnchor.constraint(equalTo: dividerLabel.bottomAnchor).isActive = true
        carbLabel.font = UIFont(name: "Verdana", size: 14)
        
        proteinLabel.translatesAutoresizingMaskIntoConstraints = false
        proteinLabel.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        proteinLabel.topAnchor.constraint(equalTo: carbLabel.bottomAnchor).isActive = true
        proteinLabel.font = UIFont(name: "Verdana", size: 14)
        
        fatLabel.translatesAutoresizingMaskIntoConstraints = false
        fatLabel.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        fatLabel.topAnchor.constraint(equalTo: proteinLabel.bottomAnchor).isActive = true
        fatLabel.font = UIFont(name: "Verdana", size: 14)
        
        sugarLabel.translatesAutoresizingMaskIntoConstraints = false
        sugarLabel.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        sugarLabel.topAnchor.constraint(equalTo: fatLabel.bottomAnchor).isActive = true
        sugarLabel.font = UIFont(name: "Verdana", size: 14)
        
        sugarWarningLabel.translatesAutoresizingMaskIntoConstraints = false
        sugarWarningLabel.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        sugarWarningLabel.topAnchor.constraint(equalTo: sugarLabel.bottomAnchor).isActive = true
        sugarWarningLabel.font = UIFont(name: "Verdana-Bold", size: 14)
    }
    
    func setupdata(){
        if let fruit = fruit{
            nameLabel.text = fruit.name
            genusLabel.text = "Genus : \(fruit.genus)"
            familyLabel.text = "Family : \(fruit.family)"
            orderLabel.text = "Order : \(fruit.order)"
            dividerLabel.text = "Nutritional value"
            
            let id = fruit.id
            let idString = String(id)
            idLabel.text = "ID : \(idString)"
            
            let carbs = fruit.nutritions.carbohydrates
            let carbString = String(carbs)
            carbLabel.text = "Carbohydrates : \(carbString)"
            
            let protein = fruit.nutritions.protein
            let proteinString = String(protein)
            proteinLabel.text = "Proteins : \(proteinString)"
            
            let fat = fruit.nutritions.fat
            let fatString = String(fat)
            fatLabel.text = "Fat : \(fatString)"
            
            let calories = fruit.nutritions.calories
            let calorieString = String(calories)
            caloriesLabel.text = "Carbohydrates : \(calorieString)"
            
            let sugar = fruit.nutritions.sugar
            let sugarString = String(sugar)
            sugarLabel.text = "Sugar : \(sugarString)"
        }
    }
    
    func setupDismissButton(){
        view.addSubview(dismissButton)
        
        dismissButton.translatesAutoresizingMaskIntoConstraints = false
        dismissButton.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -50).isActive = true
        dismissButton.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        
        dismissButton.setTitle("Tilbake",for: .normal)
        dismissButton.setTitleColor(UIColor.black, for: .normal)
        dismissButton.addTarget(self, action: #selector(dismissAction), for: .touchUpInside)
    }
    
    @objc func dismissAction(){
        self.dismiss(animated: true)
    }
}

Answer 1

The "presentation layer" of your animation is probably covering your dismiss button and preventing it from being tapped. Try adding a print statement to your dismissAction() and see if it gets called when you tap the button on a screen with the animating background.

That's a guess, but a pretty good guess.

To fix the problem, try adding a view to your view's content view, under all the other views (button, labels, etc.) Let's call that new view your colorView. Change your animation to animate the background color of the colorView instead of animating the color of the view controller's content view. I'm not certain that will fix it, but it's worth a try.