Massive CPU overuse whenever I push ViewController - Swift - Programmatically - swift

Question

I have a high CPU level whenever I push a new ViewController from the navigationController.
I used the Time Profiler tool and it turns out that the issue that is causing this CPU overuse is related to a ViewController I embedded in the rootViewController.
The ViewController I'm talking about is as follows:
class QuoteGeneratorController : UIViewController {
let interactiveShowTextView : UITextView = {
let textView = UITextView()
textView.font = UIFont(name: "avenir-black", size: 35)
textView.textColor = .white
textView.textAlignment = .left
textView.textContainer.maximumNumberOfLines = 3
textView.backgroundColor = .clear
textView.isEditable = false
textView.isSelectable = false
textView.isUserInteractionEnabled = false
return textView
}()
let progressBar : UIProgressView = {
let progressView = UIProgressView(progressViewStyle: .bar)
progressView.trackTintColor = UIColor.clear
progressView.tintColor = UIColor.white
return progressView
}()
let quotesArray = ["Hello", "Hello2", "Hello3"]
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
print("I'm called")
view.subviews.forEach { subview in
subview.layer.masksToBounds = true
subview.layer.cornerRadius = progressBar.frame.height / 2.0
}
}
override func viewDidAppear(_ animated: Bool) {
setUpAnimation()
}
override func viewDidLoad() {
setUpUI()
setUpAnimation()
}
fileprivate func setUpUI(){
view.addSubview(interactiveShowTextView)
view.addSubview(progressBar)
interactiveShowTextView.anchor(top: view.safeAreaLayoutGuide.topAnchor, leading: view.leadingAnchor, bottom: nil, trailing: view.trailingAnchor)
interactiveShowTextView.heightAnchor.constraint(equalToConstant: 150).isActive = true
progressBar.anchor(top: interactiveShowTextView.bottomAnchor, leading: interactiveShowTextView.leadingAnchor, bottom: nil, trailing: nil, padding: .init(top: 10, left: 0, bottom: 0, right: 0), size: .init(width: 70, height: 9))
}
var iterator : Int = 0
fileprivate func setUpAnimation(){
switch iterator {
case 0:
animateAndIterate()
case 1:
animateAndIterate()
case 2:
animateAndIterate()
default:
self.iterator = 0
self.setUpAnimation()
}
}
fileprivate func animateAndIterate(){
UIView.animate(withDuration: 0.0, animations: {
self.progressBar.layoutIfNeeded()
}, completion: { finished in
self.progressBar.progress = 1.0
self.interactiveShowTextView.text = self.quotesArray[self.iterator]
self.interactiveShowTextView.fadeIn()
UIView.animate(withDuration: 3, delay: 0.0, options: [.curveLinear], animations: {
self.progressBar.layoutIfNeeded()
self.perform(#selector(self.afterAnimation), with: nil, afterDelay: 2.5)
}, completion: { finished in
self.interactiveShowTextView.fadeOut()
self.progressBar.progress = 0
self.iterator = self.iterator + 1
self.setUpAnimation()
})
})
}
#objc func afterAnimation() {
self.interactiveShowTextView.fadeOut()
}
}
I actually don't know what could have caused the issue and since I'm new to time profiler I though that some of you have encountered the same process through development.
In Time Profiler I'm getting this indications:

Answer 1

When using completion blocks it's recommended to use weak references to the result. Otherwise the ARC will count every reference you used inside those block.
Use closures like this:
view.subviews.forEach { [weak self] subview in
subview.layer.masksToBounds = true
subview.layer.cornerRadius = progressBar.frame.height / 2.0
}
// (...)
fileprivate func animateAndIterate() {
UIView.animate(withDuration: 0.0,
animations: { [weak self] in
self?.progressBar.layoutIfNeeded()
}, completion: { [weak self] finished in
self?.progressBar.progress = 1.0
self?.interactiveShowTextView.text = self.quotesArray[self.iterator]
self?.interactiveShowTextView.fadeIn()
UIView.animate(withDuration: 3,
delay: 0.0,
options: [.curveLinear],
animations: { [weak self] in
self?.progressBar.layoutIfNeeded()
self?.perform(#selector(self.afterAnimation),
with: nil, afterDelay: 2.5)
}, completion: { finished in
self?.interactiveShowTextView.fadeOut()
self?.progressBar.progress = 0
self?.iterator = self.iterator + 1
self?.setUpAnimation()
})
})
}