How do I filter data to startswith instead of contains

Question

I have a UITableView that has a Search Controller for filtering the data using the code below

func updateSearchResults(for searchController: UISearchController) {
     let searchString = searchController.searchBar.text
     filteredArray = data.filter({ (country) -> Bool in let countryText: NSString = country as NSString         
     return (countryText.range(of: searchString!, options: NSString.CompareOptions.caseInsensitive).location) != NSNotFound })
     suggestionview.reloadData()
}

How do I make it so that the search filters the table by looking at the start of the string instead of matching anywhere.

For example currently if I type Lon into the search input I get a list of anything that contains Lon (still a huge list before getting to London).

Answer 1

Why do you use NSString? Prefer String in Swift 3+:

filteredArray = data.filter({ (country) -> Bool in 
    let countryText: NSString = country as NSString         
    return (countryText.range(of: searchString!, options: NSString.CompareOptions.caseInsensitive).location) != NSNotFound })
    

=>

filteredArray = data.filter({ country -> Bool in 
    return country.range(of: searchString!, options: .caseInsensitive) != nil })

You used the .caseInsenstive option, but there is also the .anchored one that migh interest you:

Search is limited to start (or end, if NSBackwardsSearch) of source string.

filteredArray = data.filter({ country -> Bool in 
    return country.range(of: searchString!, options: [.caseInsensitive, .anchored]) != nil })