如何在Swift中模仿Safari的搜索栏UI /动画？

Question

I am attempting to mimic the search bar behavior below in iOS Safari on my current app:

I mainly want the navigation bar to scroll up to a very small version when the user scrolls on the content and comes back when they scroll back up.

I've tried using scrollViewDidScroll but I cannot seem to get it to mimic that behavior. I'm unsure if I am adding the search bar correctly to the navigation bar.

let searchBar: UISearchBar = {
    let sb = UISearchBar()
    sb.autocapitalizationType = .none
    sb.autocorrectionType = .no
    sb.keyboardAppearance = UIKeyboardAppearance.default
    sb.placeholder = "Search"
    return sb
}()

fileprivate func setupNav() {
    //Basic Setup
    navigationController?.navigationBar.isTranslucent = true
    navigationController?.navigationBar.setBackgroundImage(UIImage(), for: .default)

    //Search Bar
    searchBar.sizeToFit()
    navigationItem.titleView = searchBar
}

func scrollViewDidScroll(_ scrollView: UIScrollView) {
    //Implement
}

Answer 1

let searchController                                  = UISearchController(searchResultsController: nil)
searchController.dimsBackgroundDuringPresentation     = false
searchController.searchBar.placeholder                = "Search"
searchController.searchResultsUpdater                 = self
navigationItem.searchController                       = searchController
definesPresentationContext                            = true 

Put your SearchController in the Navigation Item instead. This will add collapsable SearchBar . Additionally you can try with Navigation Item Prompt for very small title on top.