var delay: AKVariableDelay!
var delayMixer: AKDryWetMixer!
var reverb: AKCostelloReverb!
var reverbMixer: AKDryWetMixer!
var booster: AKBooster!
var tracker : AKAmplitudeTracker!
'AKVariableDelay' is unavailable: cannot find Swift declaration for this class
AKDryWetMixer' is unavailable: cannot find Swift declaration for this class
'AKCostelloReverb' is unavailable: cannot find Swift declaration for this class
'AKDryWetMixer' is unavailable: cannot find Swift declaration for this class
'AKBooster' is unavailable: cannot find Swift declaration for this class
'AKAmplitudeTracker' is unavailable: cannot find Swift declaration for this class
I receive these errors but I am able to build and to run the project, i think that something is wrong with my project settings and I don't know how to solve it.