How to add search tokens to a search field

Paul Hudson @twostraws March 14th 2023

Updated for Xcode 14.2

New in iOS 16

SwiftUI’s searchable() modifier lets us place a search bar directly into a NavigationStack, but along with just free-text search we can also allow the user to select search tokens – pre-filled chunks of text that represent a specific category or filter in your app.

This isn’t hard to do, but it does require several steps. You need:

A regular searchable() implementation that filters your results by the user’s search text.
A custom data type to represent one search token. You can’t just use strings or similar, because SwiftUI requires tokens to conform to Identifiable.
An array of all the tokens the user can select from. This might be a constant array, or it might be a published array of values that changes our time.
An array of all the tokens the user has entered. This is a subset of all the tokens, and should be factored into your filtering code.
Some code to decide how to render a single token in the list. This might be just a Text view, but it doesn’t need to be.

That might not sound too complex, but there’s an extra wrinkle: the iOS implementation of searchable() will replace your search results with your suggested tokens by default, which makes the default search functionality a lot less useful. So, I prefer to ask users to activate token filtering specifically by starting with a “#” sign, similar to Twitter and Mastodon.

Anyway, enough talk – here’s a sample implementation of searchable() with token support:

// Holds one uniquely identifiable movie.
struct Movie: Identifiable {
    var id = UUID()
    var name: String
    var genre: String
}

// Holds one token that we want the user to filter by. This *must* conform to Identifiable.
struct Token: Identifiable {
    var id: String { name }
    var name: String
}

struct ContentView: View {
    // Whatever text the user has typed so far.
    @State private var searchText = ""

    // All possible tokens we want to show to the user.
    let allTokens = [Token(name: "Action"), Token(name: "Comedy"), Token(name: "Drama"), Token(name: "Family"), Token(name: "Sci-Fi")]

    // The list of tokens the user currently has selected.
    @State private var currentTokens = [Token]()

    // The list of tokens we want to show to the user right now. Activates token selection only when searchText starts with #.
    var suggestedTokens: [Token] {
        if searchText.starts(with: "#") {
            return allTokens
        } else {
            return []
        }
    }

    // Some data to show and filter by.
    let movies = [
        Movie(name: "Avatar", genre: "Sci-Fi"),
        Movie(name: "Inception", genre: "Sci-Fi"),
        Movie(name: "Love Actually", genre: "Comedy"),
        Movie(name: "Paddington", genre: "Family")
    ]

    // The real work: filter all the movies based on search text or tokens.
    var searchResults: [Movie] {
        // trim whitespace
        let trimmedSearchText = searchText.trimmingCharacters(in: .whitespaces)

        return movies.filter { movie in
            if searchText.isEmpty == false {
                // If we have search text, make sure this item matches.
                if movie.name.localizedCaseInsensitiveContains(trimmedSearchText) == false {
                    return false
                }
            }

            if currentTokens.isEmpty == false {
                // If we have search tokens, loop through them all to make sure one of them matches our movie.
                for token in currentTokens {
                    if token.name.localizedCaseInsensitiveContains(movie.genre) {
                        return true
                    }
                }

                // This movie does *not* match any of our tokens, so it shouldn't be sent back.
                return false
            }

            // If we're still here then the movie should be included.
            return true
        }
    }

    var body: some View {
        NavigationStack {
            List(searchResults) { movie in
                Text(movie.name)
            }
            .navigationTitle("Movies+")
            .searchable(text: $searchText, tokens: $currentTokens, suggestedTokens: .constant(suggestedTokens), prompt: Text("Type to filter, or use # for tags")) { token in
                Text(token.name)
            }
        }
    }
}

Download this as an Xcode project

There are a few things that are worth pointing out in that code:

We figure out which tokens to suggest to the user inside a computed property, so we’re able to enable or disable token selection dynamically. SwiftUI expects a binding for the resulting array, so I’ve used .constant(suggestedTokens).
We don’t need to filter out the tokens the user has currently selected, because SwiftUI takes care of that automatically.
The searchable() prompt explicitly tells the user to type a “#” for tags.
The trailing closure for searchable() lets us tell SwiftUI to render each tag as some text showing its name.

In practice, I suspect you’re more likely to have multiple tags attached to each piece of data you’re working with, in which case I’d probably prefer Swift’s isSuperset(of:) set operation for comparing the user’s selected tags against those in your object. If you’re working with lots of tokens, I would also suggest you filter your list of suggested tokens based on what the user has typed so far.

One last thing: although the iOS implementation of searchable() replaces your search results with the suggested tokens, this does not happen on macOS. Instead, your search tokens appear as a popup below the search box, leaving your search results visible at the same time – it’s a much nicer experience.

Sponsor Hacking with Swift and reach the world's largest Swift community!

How to add search tokens to a search field

Similar solutions…