gallons The gallons unit of volume. Declaration@NSCopying class var gallons: UnitVolume { get } See AlsoAccessing Predefined UnitsmegaliterskiloliterslitersdeciliterscentilitersmilliliterscubicKilometerscubicMeterscubicDecimeterscubicCentimeterscubicMillimeterscubicInchescubicFeetcubicYardscubicMiles