How to create autocomplete text field in Swift

Question

What I want to be able to create is an auto complete text field in iOS.

I have a form for selecting a client, wherein the user must select a client once using a text fie

Answer 1

I did something like this in my app for looking up contacts. I will pseudo code this out for you to understand the concept:

1) Capture the characters entered into the textfield by the enduser

2) At some character count entered decide to query the server to return all entries that match - choose the character count you are comfortable with (I chose around 3-4 characters). Fewer returns more, more returns less obviously...up to you, perf and UX considerations.

3) Put the results of this server query into an array on the client. This will be your superset from which you will offer the suggestions to the user.

4) After each subsequent character entered into the text field you will now filter the array (array.filter()) by character string entered to this point. 5) tableView.reloadData() against the filtered array at each character entered.

6) I use a dataFlag variable to determine what datasource to show in the tableview depending on what the user is doing.

Note: You only query the server once to minimize perf impact

// this function is called automatically when the search control get user focus
func updateSearchResults(for searchController: UISearchController) {
  let searchBar = searchController.searchBar
  if searchBar.text?.range(of: "@") != nil {
    self.getUserByEmail(searchBar.text!)
  }
  if searchController.searchBar.text?.characters.count == 0 && dataFlag != "showParticipants" {
    dataFlag = "showInitSearchData"
    self.contacts.removeAll()
    self.participantTableView.reloadData()
  }
  if dataFlag == "showInitSearchData" && searchController.searchBar.text?.characters.count == 2 {
    self.loadInitialDataSet() {
      self.dataFlag = "showFilteredSearchData"
    }
  }
  if dataFlag == "showFilteredSearchData" {
    self.filterDataForSearchString()
  }

}

// filter results by textfield string
func filterDataForSearchString() {
  let searchString = searchController.searchBar.text
  self.filteredContacts =  self.contacts.filter({
    (contact) -> Bool in
    let contactText: NSString = "\(contact.givenName) \(contact.familyName)" as NSString

  return (contactText.range(of: searchString!, options: NSString.CompareOptions.caseInsensitive).location) != NSNotFound
  })

  DispatchQueue.main.async {
    self.participantTableView.reloadData()
  }  
}