An interpolation framework for Cocoa and Cocoa Touch.


The framework defines a protocol, LNInterpolable (Interpolable in Swift), defining a common API for interpolating between two values.

The protocol defines two methods.

Objective C

- (instancetype)interpolateToValue:(id)toValue progress:(double)progress;
- (instancetype)interpolateToValue:(id)toValue progress:(double)progress behavior:(LNInterpolationBehavior)behavior;


public func interpolate(to toValue: Any, progress: Double) -> Self
public func interpolate(to toValue: Any, progress: Double, behavior: InterpolationBehavior) -> Self

The first variant returns an interpolated value between the original and toValue according to progress, using the default behavior.
The second is similar, but receives a behavior modifier. Each implementation can use this to choose how to implement the interpolation between the values. A default value of LNInterpolationBehaviorUseDefault (.useDefault in Swift) is always available.

Provided Implementations

The framework provides implementation for the most common cases where interpolation may be needed.

NSValue and NSNumber

An implementation is provided for NSValue, which provides support for the following values:

  • Numbers (NSNumber)
    • Decimal numbers (NSDecimalNumber)
  • Core Graphics: CGPoint, CGSize, CGVector, CGRect, CGAffineTransform (NSValue)
  • UIKit: UIOffset, UIEdgeInsets (NSValue)
  • AppKit: NSEdgeInsets (NSValue)



UIColor and NSColor

An implementation is provided for colors (both for iOS and macOS). By default, color interpolation is performed in Lab colorspace for best possible interpolation quality. If performance is an issue, you may use LNInterpolationBehaviorUseRGBColorSpace (.useRGBColorSpace in Swift) to specify a behavior where RGB colorspace is used.


Demo Playground

A demo playground is provided. Open LNInterpolationExample/LNInterpolationExample.xcworkspace and build the framework for macOS. Open the playground and explore the available pages.

Adding to Your Project


Add the following to your Cartfile:

github "LeoNatan/LNInterpolation"


Drag the LNInterpolation.xcodeproj project to your project, and add LNInterpolation.framework to Embedded Binaries in your project target's General tab. Xcode should sort everything else on its own.