This Swift extension allows to use more timing functions than the default ones provided by `CAMediaTimingFunction`. It's based on the work of Christian Giordano: https://gist.github.com/nuthinking/7415509

CAMediaTimingFunctionExtension.swift

import QuartzCore

enum BezierType {
    case Default
    case Linear

    case EaseIn
    case EaseOut
    case EaseInOut

    case SineIn
    case SineOut
    case SineInOut

    case QuadIn
    case QuadOut
    case QuadInOut

    case CubicIn
    case CubicOut
    case CubicInOut

    case QuartIn
    case QuartOut
    case QuartInOut

    case QuintIn
    case QuintOut
    case QuintInOut

    case ExpoIn
    case ExpoOut
    case ExpoInOut

    case CircIn
    case CircOut
    case CircInOut

    case BackIn
    case BackOut
    case BackInOut
}

extension CAMediaTimingFunction {
    convenience init(type: BezierType) {
        switch type {
            case .Default: self.init(name: kCAMediaTimingFunctionDefault)
            case .Linear: self.init(name: kCAMediaTimingFunctionLinear)

            case .EaseIn: self.init(name: kCAMediaTimingFunctionEaseIn)
            case .EaseOut: self.init(name: kCAMediaTimingFunctionEaseOut)
            case .EaseInOut: self.init(name: kCAMediaTimingFunctionEaseInEaseOut)

            case .SineIn: self.init(controlPoints: 0.45, 0, 1, 1)
            case .SineOut: self.init(controlPoints: 0, 0, 0.55, 1)
            case .SineInOut: self.init(controlPoints: 0.45, 0, 0.55, 1)

            case .QuadIn: self.init(controlPoints: 0.43, 0, 0.82, 0.60)
            case .QuadOut: self.init(controlPoints: 0.18, 0.4, 0.57, 1)
            case .QuadInOut: self.init(controlPoints: 0.43, 0, 0.57, 1)

            case .CubicIn: self.init(controlPoints: 0.67, 0, 0.84, 0.54)
            case .CubicOut: self.init(controlPoints: 0.16, 0.46, 0.33, 1)
            case .CubicInOut: self.init(controlPoints: 0.65, 0, 0.35, 1)

            case .QuartIn: self.init(controlPoints: 0.81, 0, 0.77, 0.34)
            case .QuartOut: self.init(controlPoints: 0.23, 0.66, 0.19, 1)
            case .QuartInOut: self.init(controlPoints: 0.81, 0, 0.19, 1)

            case .QuintIn: self.init(controlPoints: 0.89, 0, 0.81, 0.27)
            case .QuintOut: self.init(controlPoints: 0.19, 0.73, 0.11, 1)
            case .QuintInOut: self.init(controlPoints: 0.9, 0, 0.1, 1)

            case .ExpoIn: self.init(controlPoints: 1.04, 0, 0.88, 0.49)
            case .ExpoOut: self.init(controlPoints: 0.12, 0.51, -0.4, 1)
            case .ExpoInOut: self.init(controlPoints: 0.95, 0, 0.05, 1)

            case .CircIn: self.init(controlPoints: 0.6, 0, 1, 0.45)
            case .CircOut: self.init(controlPoints: 1, 0.55, 0.4, 1)
            case .CircInOut: self.init(controlPoints: 0.82, 0, 0.18, 1)

            case .BackIn: self.init(controlPoints: 0.77, -0.63, 1, 1)
            case .BackOut: self.init(controlPoints: 0, 0, 0.23, 1.37)
            case .BackInOut: self.init(controlPoints: 0.77, -0.63, 0.23, 1.37)
        }
    }
}

Example.swift

let animateOpacity = CABasicAnimation(keyPath: "opacity")
animateOpacity.duration = 0.3
animateOpacity.timingFunction = CAMediaTimingFunction(type: .ExpoOut)

layer.opacity = 1.0
layer.removeAllAnimations()
layer.addAnimation(animateOpacity, forKey: "opacity")