BLACK FRIDAY: Save 50% on all books and bundles! >>

How to make gesture recognizers work together using require(toFail:)

Swift version: 5.2

Paul Hudson    @twostraws   

It’s common to have multiple gesture recognizers attached to a single view, all doing different things depending on the user’s taps on your screen. By default, iOS lets them fight for control, but usually you want to execute them in some sort of particular order: one gesture should only be matched if another failed.

For example, here are two gesture recognizers that exist on the same view:

let swipe = UISwipeGestureRecognizer(target: self, action: #selector(executeSwipe))
let tap = UITapGestureRecognizer(target: self, action: #selector(executeTap))

view.addGestureRecognizer(swipe)
view.addGestureRecognizer(tap)

A swipe gesture is a tap followed by a linear movement, whereas a tap is just a tap – we need to make sure the swipe gesture has definitely not been recognizer before the tap gesture is checked.

iOS often does a fairly good job of this, but there’s no need to leave it up to chance: if you call require(toFail:) on the tap gesture recognizer, passing in the swipe recognizer, iOS will definitely make sure they don’t compete:

tap.require(toFail: swipe)

Save 50% in my Black Friday sale.

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

Available from iOS 3.2

Similar solutions…

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.

BUY OUR BOOKS
Buy Pro Swift Buy Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Coding Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift (Vapor Edition) Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Advanced iOS Volume Three Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with macOS Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Server-Side Swift (Kitura Edition) Buy Beyond Code

Was this page useful? Let us know!

Average rating: 4.1/5

Link copied to your pasteboard.