mesqueeb / Debouncify

🔂 Swift actor to debounce anything & SwiftUI View modifier `onChange` with debounce

Debouncify 🔂

.package(url: "https://github.com/mesqueeb/Debouncify", from: "0.1.0")

• onChangeDebounced is a SwiftUI View modifier like onChange but makes it debounce on every call by a specified duration
• Debouncify is a Swift actor to easily wrap a function and make it debounce on every call by a specified duration

"Debouncing" is to execute a function after a short delay. If the function is called twice within this time, the function will only be executed once after the specified duration has passed after the last call.

SwiftUI onChangeDebounced View modifier

Suppose you have a function that you want to execute on every keystroke, but debounce it by 300ms to only execute it after the user has stopped typing for a certain amount of time.

Example:

@State private var query: String = ""

func search(_ query: String) async {
    print("searching!")
    // your search API call logic...
}

var body: some View {
    TextField("Search...", text: $query)
        .onChangeDebounced(of: query, after: .milliseconds(300)) { _oldValue, newValue in
            search(newValue)
        }
}

Canceling the debounced Task

If you need to cancel the debounced execution of your search function, eg. when the user hits ESC, you can pass a binding with a Task which you can then cancel.

Example:

@State private var query: String = ""

func search(_ query: String) async {
    print("searching!")
    // your search API call logic...
}

/// The search Task is added by `onChangeDebounced` below
@State private var searchTask: Task<Void, never>? = nil

var body: some View {
    TextField("Search...", text: $query)
    .onChangeDebounced(of: query, after: .milliseconds(300), task: $searchTask) { _oldValue, newValue in
        search(newValue)
    }
    .onKeyPress(.return) {
        searchTask?.cancel()
        search(query)
        return .handled
    }
    .onKeyPress(.escape) {
        searchTask?.cancel()
        return .handled
    }
}

Swift Debouncify Actor

Use Debouncify to wrap a function and it will automatically get debounced each subsequent call.

Example:

// Example debounced function
func search() async {
    print("searching!")
    // your search API call logic...
}

// Using Debouncify to wrap the function
let searchAfter300ms = Debouncify(call: search, after: .milliseconds(300))

// Usage
Task {
    Task { await searchAfter300ms() }
    try await Task.sleep(for: .milliseconds(100))
    Task { await searchAfter300ms() }
    try await Task.sleep(for: .milliseconds(100))
    Task { await searchAfter300ms() }
}
// it will only print "searching!" once after 300ms

Canceling the debounced Task

You can cancel the debounced task by calling the cancel method on the Debouncify instance.

Example:

// Example debounced function
func search() async {}

let searchAfter300ms = Debouncify(by: .milliseconds(300), search)
var task: Task<Any, Any>? = nil

Task { await searchAfter300ms() }
// if the search needs to be cancelled before the Task above finishes
Task { await searchAfter300ms.cancel() }

Documentation

See the documentation for more info.