MotionMachine is a powerful yet elegant animation library for Swift. It offers sensible default functionality that abstracts most of the hard work away, allowing you to focus on your work. But MotionMachine also makes it easy to dive in and modify for your own needs, whether that be custom motion classes, supporting custom value types, or new easing equations.
MotionMachine provides a modular, generic platform for manipulating values. Its animation engine was built from the ground up to support not just UIKit values, but property values of any class you want to manipulate. MotionMachine does support most major UIKit types out of the box and provides syntactic sugar to easily manipulate them. For instance, individual values of UIView frames can be directly targeted with a keyPath, such as "frame.size.width". Individual UIColor properties can be animated by specifying a keyPath shorthand for them, such as "red", "hue", or "alpha".
- Motions can be grouped, sequenced, and nested in any arrangement.
- Includes both static and physics-based motion classes, and both support additive animation.
- Powerfully modular – most aspects can be customized or outright replaced to fit your specific needs.
- Provides status callback closures for many types of motion events.
This complex animation was created with the code sample below. These Motion classes animate the NSLayoutConstraints of the circle views (the constraints object in the target parameter is a dictionary of NSLayoutConstraint references) as well as one of their backgroundColor properties. A MotionGroup object is used to synchronize the four Motion objects and reverse their movements.
let group = MotionGroup()
.add(Motion(target: constraints["circleX"]!,
properties: [PropertyData("constant", 200.0)],
duration: 1.0,
easing: EasingQuartic.easeInOut()))
.add(Motion(target: constraints["circleY"]!,
properties: [PropertyData("constant", 250.0)],
duration: 1.4,
easing: EasingElastic.easeInOut()))
.add(Motion(target: circle,
properties: [PropertyData("backgroundColor.blue", 0.9)],
duration: 1.2,
easing: EasingQuartic.easeInOut()))
.add(Motion(target: constraints["circle2X"]!,
properties: [PropertyData("constant", 300.0)],
duration: 1.2,
easing: EasingQuadratic.easeInOut())
.reverses(withEasing: EasingQuartic.easeInOut()))
.start()The atom of MotionMachine is the PropertyData class. Each instance of this class provides movement data that is specific to one property or discrete object. This class is used by Motion to animate one or more property values of a single class object. The actual retrieval and updating of values is handled by ValueAssistant classes. MotionMachine has assistants for several standard Quartz and UIKit value types, but you can add your own value assistants to a Motion to increase the types it can use.
All of the included motion classes in MotionMachine adopt the Moveable protocol which enables them to work seamlessly together. By using the MotionGroup and MotionSequence collection classes to control multiple motion objects – even nesting multiple layers – you can create complex animations with little effort. If you want to use your own custom motion classes within the MotionMachine ecosystem, simply have them adopt the Moveable protocol. However, the base Motion class offers such modularity that in most cases you can just add to or replace the components you need with your own implementation.
Motion uses a keypath (i.e. "frame.origin.x") to target specific properties of an object and transform their values over a period of time via an easing equation.
[Motion] --------------------> |
MotionGroup is a MoveableCollection class that manages a group of Moveable objects, controlling their movements in parallel. It's handy for controlling and synchronizing multiple Moveable objects. MotionGroup can even control other MoveableCollection objects.
[Motion] --------------> |
[Motion] --------------------> |
[MotionSequence] ----------------> |
MotionSequence is a MoveableCollection class which moves a collection of Moveable objects in sequential order, even other MoveableCollection objects. MotionSequence provides a powerful and easy way of chaining together individual motions to create complex and fluid compound animations.
0.[Motion] -------> |, 1.[MotionGroup] -------> |, 2.[PhysicsMotion] -------> |
Get started with the Moveable Classes guide, which explains all of the basic motion classes in MotionMachine.
Also see the Examples project to see all the MotionMachine classes in action.
[•] MotionMachine uses Key-Value Coding (KVC) to introspect objects and retrieve and set their property values using keypaths. Because Swift currently offers no native ability in this regard, objects whose properties should be modified by MotionMachine must inherit from NSObject. If and when more dynamism is added to Swift (and the author of this library hopes that is the case), MotionMachine will hopefully be able to do away with this restriction.
[•] Because native Swift structs cannot inherit from NSObject, Swift structs unfortunately cannot be used with MotionMachine at this time.
[•] The KVC provided by NSObject is not able to evaluate Optional values. Properties you wish to modify with MotionMachine must not be Optionals.
[•] Swift on Linux is not currently supported due to the lack of Foundation and Core Graphics frameworks on that platform.
If you use CocoaPods:
use_frameworks!
pod "MotionMachine", "~> 1.0.0"Or add the Classes directory to your project.
MotionMachine currently requires:
- Swift 2.2
- Xcode 7.3
- iOS 8.0 or later, tvOS 9.0 or later
Animation is a term typically associated with the movement of visual elements on-screen. But MotionMachine was designed to animate any kind of values, whether that be view positions, sound properties, 3D model vertices, or most any values you can think of. So the word motion is used because this library controls the movement of any type of value from one position to another over a period of time.
MotionMachine was created by Brett Walker. It is based on the author's Objective-C library PMTween. The MotionMachine logo design is also by the author.
MotionMachine is licensed under the MIT License. See LICENSE for details.
I'd love to know if you use MotionMachine in your projects!