NEW! Check out my latest book, Testing Swift! >>

How to measure touch strength using 3D Touch

Paul Hudson       @twostraws

You can read a user's 3D Touch strength using the force property of a UITouch, which is best used when compared against the touch.maximumPossibleForce. For example, you can divide one into the other to see how much relative strength is applied, or do a straight comparison to check to see whether the user is pressing as hard as possible.

Before you try to make use of 3D Touch, make sure it's available by checking the forceTouchCapability of your current trait collection. Here's an example touchesMoved() implementation that checks whether 3D Touch is available and the user is pressing hard:

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    super.touchesMoved(touches, with: event)

    if let touch = touches.first {
        if view.traitCollection.forceTouchCapability == .available {
            if touch.force == touch.maximumPossibleForce {
                // user pressed hard – do something!
            }
        }
    }
}

Available from iOS 7.0 – see Hacking with Swift tutorial 37

Did this solution work for you? Please pass it on!

Other people are reading…

About the Swift Knowledge Base

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

Hacking with watchOS

Transfer your Swift skills to watchOS the easy way, and learn to build real-world apps in the process!

MASTER SWIFT NOW
Buy Testing Swift Buy Practical iOS 12 Buy Pro Swift Buy Swift Design Patterns Buy Swift Coding Challenges Buy Server-Side Swift (Vapor Edition) Buy Server-Side Swift (Kitura Edition) Buy Hacking with macOS Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with Swift Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let me know!

Click here to visit the Hacking with Swift store >>