Unwanted UITableView reload animation when navigating from iOS 11 search controller - ios

Question

I have a view controller with a tableview containing a list of chats, a search controller enbeded in the navigation item (iOS 11 feature)
let searchController = UISearchController(searchResultsController: nil)
searchController.dimsBackgroundDuringPresentation = false
navigationItem.searchController = searchController
definesPresentationContext = true
When the user taps a chat in the table view the app pushes a new view controller with another table view containing messages for that chat. That works like it is supposed to:
The problem is that when the user activates the search controller, find some chat and taps it, the pushed view controller containing table view with the chat messages does some really strange animation with the table view that should not happen:
I load the data before the actual navigation and bind it to the table view in viewDidLoad using just reload() on the table view. The problematic table view uses auto layout and custom cells.
The problem is very similar to UITableView has unwanted animation when reloadData is called but for me it only happens when the iOS 11 search controller is active.
Edit: If I remove tableView.rowHeight = UITableViewAutomaticDimension and use a fixed height using func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat the problem is still there

Answer 1

If you just hide the searchBar before pushing a new viewController then it may fix your problem.
You need to create a global variable for searchBarCancelButton and find the cancel button from its subviews when you search something
let buttons = searchController.searchBar.subviews.first?.subviews.filter { (view) -> Bool in
return NSStringFromClass(view.classForCoder) == "UINavigationButton"
} as? [UIButton]
searchBarCancelButton = buttons?.first
then you can manually cancel it.
self.searchBarCancelButton?.sendActions(for: .touchUpInside)

Answer 2

Personally, I would simply hide the searchView controller before presenting the new view controller.
( Using UIView.animates with a completion handler for example )
I would not try to investigate further because since iOS11, there is an esoteric problem in the safe area management. A bug ? :)
Even the launch screens layouts are not correctly handled.
So many majors logos miss their middle part at launch !

Answer 3

You can try to call cell.layoutIfNeeded() right after dequeuing and setting a content of the cell

Answer 4

iOS 11 completely revamped the safe area API, including scroll view inset adjustment behaviors, which can cause unwanted animation when ignored. Therefore, disable automatic content inset adjustment for the scroll view with the unwanted animation:
if #available(iOS 11.0, *) {
tableView.contentInsetAdjustmentBehavior = .never
} else {
// < iOS 11 logic
}

Answer 5

Do not invoke reloadData() method in your viewDidLoad or viewWillAppear. Instead of this reload your tableView with empty data in viewDidLoad so your tableView will show nothing and then in your viewDidAppear invoke reloadData() method to load all of your chats. This will restrict your tableView from loading with unwanted animation.
var shouldShowEmpty = true
func viewDidLoad() {
super.viewDidLoad()
tableView.reloadData()
}
func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
shouldShowEmpty = false
tableView.reloadData()
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if shouldShowEmpty {
return 0
}
return yourArray.count
}

Answer 6

As per attachment, It looks like due to auto layout, cell's element's height was zero (UILabel or UIImageView) and then suddenly when table view reloads it gets the data inside the cell which increase its height(automatic dimension or whatever) which cause this animation.
Try to push it without animation or try to set fix cell's element's height and width and check is it still showing this animation.
Did you check without invoking UISearchBar, If you select on any cell same animation is happening ?? or did you try to remove UISearchbar and select on the cell and check the animation part ?
Please share your code so we can see more clearly.

Answer 7

I have had a similar problem, and I believe that solution is the same. The keyboard is causing the problem, to be more correct, keyboardWillHideNotification trigger. You have text field at the bottom, that probably listens to notifications for keyboard show/hide, where layoutIfNeeded() is triggered if you animate bottom constraint so that your keyboard doesn't overlap your text field. So when you finish your search in the search text field, keyboardWillHideNotification gets triggered at an unwanted time. I solved my issue by calling:
resignFirstResponder()
for the text field that causes this event. In my case, that was after pressing the button, in your, I believe it's in didSelect tableView cell in the search table view.
If you are still active at this issue, please let me know if you manage to solve it. I broke my head trying to solve this issue, which apparently is so simple and straightforward.

Answer 8

In VC2 Try a delay function before reloading table
DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
tableView.reloadData
}
or else
In VC1 in didSelect resign first responder of search controller before pushing to VC2
or
In VC1 in didSelect resign first responder of search controller and set a delay before pushing to VC2.