How to use Spring: iOS animations in Swift, step by step

What Spring does and who it suits

Spring gives you a set of ready-made animations for user interface views, so you do not have to write animation math by hand. It is aimed at iOS developers who want common UI motion quickly, and at developers who prefer setting animations in Storyboard with little code.

The README states it was updated for Swift 4.2 and requires Xcode 10 and Swift 4.2, so it fits best with older iOS projects of that era.

• Good fit: iOS projects built on Swift 4.2 and Xcode 10, quick prototypes, Storyboard-based interfaces.
• Poor fit: current Swift or Xcode versions, Android or web projects, and teams that need a documented, versioned API.

What you need before installing

The README lists Xcode 10 and Swift 4.2 as requirements. CocoaPods is optional and only needed if you use the pod install route. The project is iOS-only.

• Xcode 10
• Swift 4.2
• CocoaPods (optional)

Install Spring with the folder or CocoaPods

The simplest route is to clone the repository and drop the Spring folder into your Xcode project. When adding it, enable "Copy items if needed" and "Create groups".

If you use CocoaPods, add the Spring entry to your Podfile, including use_frameworks!, and then install as usual.

• Clone the repository and copy the Spring folder into your project.
• Enable "Copy items if needed" and "Create groups" when adding it.
• Or add the CocoaPods entry shown below to your Podfile.

Animate a view in Storyboard

In Storyboard, select the view, open the Identity Inspector and set its class to SpringView. Then set the animation properties in the Attribute Inspector. Autostart lets the animation run without code, and Autohide saves you from setting layer.alpha = 0 in viewDidLoad().

• Connect the UIView to the SpringView class in the Identity Inspector.
• Set the animation properties in the Attribute Inspector.
• Use Autostart if you do not want to start the animation in code.

Animate a view in code

To animate in code, set the animation name on the view's layer and call animate(). The README's example uses squeezeDown. You can also chain animations: set a starting position, then call animateToNext with a closure that sets the next animation and calls animateTo().

• Functions in the README: animate(), animateNext { ... }, animateTo(), animateToNext { ... }.
• Properties include force, duration, delay, damping, velocity, repeatCount, scale, x, y and rotate.
• Not all properties work together, so test combinations in the demo app.

Choose animations and curves

Spring includes named animations such as shake, pop, morph, wobble, swing, flipX, flipY, fall, squeeze variants, slide variants, fade variants, zoomIn, zoomOut and flash. Curves include spring, linear, easeIn, easeOut and easeInOut. The README links to a demo screen that shows the animations.

• Animation examples: shake, pop, fadeIn, slideUp, zoomIn, flash.
• Curve examples: spring, linear, easeIn, easeOut, easeInOut.

Known limits and where to get help

The README records one known issue: animations won't autostart when a view is reached via performSegueWithIdentifier. Tutorials are linked from Design+Code, and the project's changelog lives on its GitHub wiki. The README is short and no release is published, so check the repository's current state before relying on it.

• Known issue: Autostart does not work when the view is reached via performSegueWithIdentifier.
• Tutorials: Design+Code (designcode.io/swiftapp).
• Changelog: the CHANGELOG page on the GitHub wiki.