Memory won't be released until APP enters background - ios

Question

I'm working on a app with a side menu, using two ViewController in a ContainController.
And when after close the side menu ViewController(the deinit method is called), the memory just would not be released(it's about 23 MiB), until the app entered background.
The "Leaks" tool build in Xcode 9 says there's no memory leak at all...
Anyone could tell me what's wrong?
Thanks a lot in advance!
import UIKit
import CoreData
enum MenuState {
case Collapsed
case Expanding
case Expanded
}
class ContainerViewController: UIViewController {
weak var managedObjectContext: NSManagedObjectContext!
weak var mainViewController: MasterViewController!
weak var menuViewController: MenuViewController?
var currentState = MenuState.Collapsed {
didSet {
let shouldShowShadow = currentState != .Collapsed
showShadowForMainViewController(shouldShowShadow: shouldShowShadow)
}
}
override func viewDidLoad() {
super.viewDidLoad()
mainViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "mainView") as! MasterViewController
view.addSubview(mainViewController.view)
DispatchQueue.global(qos: .userInteractive).async {
self.mainViewController.managedObjectContext = self.managedObjectContext
self.addChildViewController(self.mainViewController)
self.mainViewController.didMove(toParentViewController: self)
}
let panGestureRecognizer = UIPanGestureRecognizer(target: self, action:#selector(self.handlePanGesture(_:)))
self.mainViewController.view.addGestureRecognizer(panGestureRecognizer)
let tapGestureRecognizer = UITapGestureRecognizer(target: self, action:#selector(self.handleTapGesture))
self.mainViewController.view.addGestureRecognizer(tapGestureRecognizer)
}
#objc func handlePanGesture(_ recognizer: UIPanGestureRecognizer) {
switch(recognizer.state) {
case .began:
let dragFromLeftToRight = (recognizer.velocity(in: view).x > 0)
if (currentState == .Collapsed && dragFromLeftToRight) {
currentState = .Expanding
addMenuViewController()
}
case .changed:
let positionX = recognizer.view!.frame.origin.x + recognizer.translation(in: view).x
recognizer.view!.frame.origin.x = positionX < 0 ? 0 : positionX
let boundX = mainViewController.view.frame.width - menuViewExpandedOffset
if positionX > 0 {
recognizer.view!.frame.origin.x = positionX > boundX ? boundX : positionX
}
recognizer.setTranslation(.zero, in: view)
case .ended:
let boundX = mainViewController.view.frame.width - menuViewExpandedOffset
let hasMovedhanHalfway = (recognizer.view!.frame.origin.x > boundX * 0.3)
animateMainView(shouldExpand: hasMovedhanHalfway)
default:
break
}
}
#objc func handleTapGesture() {
if currentState == .Expanded {
animateMainView(shouldExpand: false)
}
}
//ADD MENUVC
func addMenuViewController() {
if (menuViewController == nil) {
menuViewController = UIStoryboard(name: "Main", bundle: nil)
.instantiateViewController(withIdentifier: "menuView")
as? MenuViewController
view.insertSubview(menuViewController!.view, at: 0)
addChildViewController(menuViewController!)
menuViewController!.didMove(toParentViewController: self)
}
}
let menuViewExpandedOffset: CGFloat = 480
func animateMainView(shouldExpand: Bool) {
if (shouldExpand) {
currentState = .Expanded
animateMainViewXPosition(targetPosition: mainViewController.view.frame.width -
menuViewExpandedOffset)
}
else {
animateMainViewXPosition(targetPosition: 0) { finished in
self.currentState = .Collapsed
self.menuViewController?.view.removeFromSuperview()
self.menuViewController?.removeFromParentViewController()
self.menuViewController = nil
}
}
}
func animateMainViewXPosition(targetPosition: CGFloat,
completion: ((Bool) -> Void)! = nil) {
UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 1.0,
initialSpringVelocity: 0, options: .curveEaseOut, animations: {
self.mainViewController.view.frame.origin.x = targetPosition
}, completion: completion)
}
func showShadowForMainViewController(shouldShowShadow: Bool) {
if (shouldShowShadow) {
mainViewController.cameraBGimage.layer.shadowOpacity = 0.6
mainViewController.cameraBGimage.layer.shadowOffset = CGSize(width: 0, height: 1)
} else {
mainViewController.cameraBGimage.layer.shadowOpacity = 0.0
}
}
}

Answer 1

Provably there is nothing wrong with your app. The iOS system will manage the memory the way it thinks it is best.
If your objects are deallocated when they should be, then you are fine. If you want to get a better understanding of when your views are deallocated you can always use de Allocations tool of the Instruments and filter it by your app's name.