mluton/SwipeSequenceGestureRecognizer

A custom gesture recognizer for a configurable sequence of swipes.

Introduction

This is a custom gesture recognizer for iOS that will recognize a sequence of swipes in the up, down, left, and right directions. This was born out of a need for a Konami Code-like gesture, but without the button presses and the ability to specify a custom sequence of swipes instead of the traditional Konami sequence (up, up, down, down, left, right, left, right).

Usage

To use this in your project copy SwipeSequenceGestureRecognizer.swift into your project. By default, the swipe sequence is the same as the Konami Code D-pad sequence: up, up, down, down, left, right, left, right. This can be changed by setting the requiredSequence property.

let swipeSequence = SwipeSequenceGestureRecognizer(target: self, action: #selector(self.handleSwipeSequence))
swipeSequence.requiredSequence = [.down, .down, .up, .left]
view.addGestureRecognizer(swipeSequence)

The directions are provided by a SwipeDirection enum.

enum SwipeDirection {
  case up
  case down
  case left
  case right
}

The handler will need to test for the .ended state specifically as it will be called while the gesture is being entered as the state changes and each swipe is being made.

@objc func handleSwipeSequence(sender: UITapGestureRecognizer) {
  if sender.state == .ended {
    print("swipe sequence entered" )
  }
}

Background

There are a couple of existing projects that implement the Konami Code for iOS.

• https://github.com/objectiveSee/DRKonamiCode
• https://github.com/Plopix/PlopixKonamiCodeGesture

After studying both projects, I pulled what I felt were the best ideas from each into this project. Eliminating the need to deal with the 'B' 'A' button presses also allowed for a simpler/shorter implementation. The end result is a custom gesture recognizer that recognizes a sequence of swipe gestures. This can be used to implement easter eggs or secret functionality in iOS apps.

Comments, Feedback, Suggestions: Michael Luton