MusicTheory

A music theory library with

Key

Pitch

Interval

Scale

Chord

Requirements

• Swift 4.0+
• iOS 8.0+
• macOS 10.9+
• tvOS 9.0+
• watchOS 2.0+

Install

CocoaPods

pod 'MusicTheorySwift'

Swift Package Manager

let package = Package(
  name: ...
  dependencies: [
    .package(url: "https://github.com/cemolcay/MusicTheory.git")
  ],
  targets: ...
)

Usage

MusicTheory

Pitch

Key

Scale

Chord

All data types conforms

Codable

CustomStringConvertable

Pitch

Accident

RawPresentable

Int

ExpressibleByIntegerLiteral

Int

Pitch

and

Key

• All keys can be defined with

  Key

  struct.
• It has a

  KeyType

  where you can set the base key like C, D, A, G, and an

  Accidental

  where it can be

  .natural

  ,

  .flat

  ,

  sharp

  or more specific like

  .sharps(amount: 3)

  .
• You can create

  Pitch

  es with a

  Key

  and octave.
• Also, you can create

  Pitch

  es with MIDI note number.

  rawValue

  of a pitch is its MIDI note number.

• Pitch

  ,

  Key

  ,

  Accidental

  structs are equatable,

  +

  and

  -

  custom operators defined for making calculations easier.
• Also, there are other helper functions or properties like frequency of a note.
• You can define them with directly string representations as well.

let dFlat = Key(type: d, accidental: .flat)
let c4 = Pitch(key: Key(type: .c), octave: 4)
let aSharp: Key = "a#" // Key(type: .a, accidental: .sharp)
let gFlat3: Pitch = "gb3" // or "g♭3" or "Gb3" is Pitch(key: (type: .g, accidental: .flat), octave: 3)

Interval

• Intervals are halfsteps between pitches.
• They are

  IntegerLiteral

  and you can make add/substract them between themselves, notes or note types.
• You can build up a custom interval with its quality, degree and semitone properties.
• You can build scales or chords from intervals.
• Minor, major, perfect, augmented and diminished intervals up to 2 octaves are predefined.

ScaleType

and

Scale

• ScaleType

  enum defines a lot of readymade scales.
• Also, you can create a custom scale type by

  ScaleType.custom(intervals: [Interval], description: String)

• Scale

  defines a scale with a scale type and root key.
• You can generate notes of scale in an octave range.
• Also you can generate

  HarmonicField

  of a scale.
• Harmonic field is all possible triad, tetrad or extended chords in a scale.

let c = Key(type: .c)
let maj: ScaleType = .major
let cMaj = Scale(type: maj, key: c)

ChordType

and

Chord

• ChordType

  is a struct with

  ChordPart

  s which are building blocks of chords.
• You can define any chord existing with

  ChordType

  .
• Thirds, fifths, sixths, sevenths and extensions are parts of the

  ChordType

  .
• Each of them also structs which conforms

  ChordPart

  protocol.

• Chord

  defines chords with type and a root key.
• You can generate notes of chord in any octave range.
• You can generate inversions of any chord.

let m13 = ChordType(
  third: .minor,
  seventh: .dominant,
  extensions: [
    ChordExtensionType(type: .thirteenth)
  ])
let cm13 = Chord(type: m13, key: Key(type: .c))

• You can generate chord progressions with

  ChordProgression

  enum.
• For any scale, in any harmonic field, for any inversion.

let progression = ChordProgression.i_ii_vi_iv
let cSharpHarmonicMinorTriadsProgression = progression.chords(
  for: cSharpHarmonicMinor,
  harmonicField: .triad,
  inversion: 0)

Tempo

and

TimeSignature

• Tempo is a helper struct to define timings in your music app.
• TimeSignature is number of beats in per measure and

  NoteValue

  of each beat.
• You can calculate notes duration in any tempo by ther

  NoteValue

  .
• Note value defines the note's duration in a beat. It could be whole note, half note, quarter note, 8th, 16th or 32nd note.

HarmonicFunctions

• Harmonic functions is a utility for finding related notes or chords in a scale when composing.
• You can create recommendation engines or chord generators with that.

Playgrounds

• You can experiment with the library right away in the Xcode Playgrounds!
• After cloning the project, build it for the Mac target,
• Go to playground page in the project,
• Make sure the macOS platform is selected,
• And make sure the "Build Active Scheme" option is selected in the playground settings.
• There are some recipes ready in the playground page, you can just run them right away.

Documentation

Full documentation is here

Unit Tests

You can find unit tests in

MusicTheoryTests

⌘+U

AppStore

This library battle tested in my apps for iOS, macOS, watchOS and tvOS, check them out!
KeyBud (iOS, watchOS, tvOS, macOS)
FretBud (iOS, watchOS, tvOS)
ChordBud (iOS)
ArpBud (iOS)
ScaleBud (iOS, AUv3)
StepBud (iOS, AUv3)
RhythmBud (iOS, AUv3)
ArpBud 2 (iOS, AUv3)
ChordBud 2 (iOS, AUv3)