     }
 }
 
-extension ViewController: AudioEngineIFProtocol {
-    func audioEngine(_ engine: AudioEngineIF,
-        didTriggeredTracks tracks: [NSNumber],
-        step stepNo: Int32,
-        atTime absoluteTime: UInt64)
-    {
-        print("\(tracks)")
-        DispatchQueue.main.async {
-        }
-    }
-}

        var track3 = [Bool](repeating: false, count: _engine.numberOfSteps)

        for i in 0 ..< _engine.numberOfSteps {
            track0[i] = ((i % 4) == 0)
            track1[i] = ((i % 8) == 0)
            track2[i] = ((i % 2) == 0)
            track3[i] = ((i % 1) == 0)
        }
        _engine.setStepSequence(track0, ofTrack: 0)
        _engine.setStepSequence(track1, ofTrack: 1)


        bpmSliderUpdated(_bpmSlider)
        stepSliderUpdated(_stepSlider)

        _engine.onTriggerdCallback = {
            (tracks: [Int], stepNo: Int, absoluteTime: UInt64) in
            print("\(absoluteTime): <\(stepNo)> \(tracks)")
        }
    }

    override func didReceiveMemoryWarning() {
