added example of using two knobs

Author: analogcode

KnobView.swift

@@ -8,8 +8,14 @@
 
 import UIKit
 
+protocol KnobDelegate {
+    func updateKnobValue(_ value: Double, tag: Int)
+}
+
 @IBDesignable
 class KnobView: UIView {
+    
+    var delegate: KnobDelegate?
 
     var minimum = 0.0 {
         didSet {
@@ -85,6 +91,8 @@ class KnobView: UIView {
 
         lastX = touchPoint.x
         lastY = touchPoint.y
+        
+        delegate?.updateKnobValue(value, tag: self.tag)
     }
 
 }

SynthUISpike/Base.lproj/Main.storyboard

@@ -21,19 +21,33 @@
                         <rect key="frame" x="0.0" y="0.0" width="1024" height="337"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
-                            <view contentMode="center" fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="DJU-Fx-KsR" customClass="KnobView" customModule="SynthUISpike" customModuleProvider="target">
-                                <rect key="frame" x="175" y="103" width="130" height="130"/>
+                            <view tag="100" contentMode="center" fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="DJU-Fx-KsR" customClass="KnobView" customModule="SynthUISpike" customModuleProvider="target">
+                                <rect key="frame" x="155" y="103" width="130" height="130"/>
                                 <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
                                 <color key="backgroundColor" white="0.0" alpha="0.0" colorSpace="calibratedWhite"/>
                             </view>
+                            <view tag="101" contentMode="center" fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="7A7-28-Zh2" customClass="KnobView" customModule="SynthUISpike" customModuleProvider="target">
+                                <rect key="frame" x="354" y="113" width="110" height="110"/>
+                                <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
+                                <color key="backgroundColor" white="0.0" alpha="0.0" colorSpace="calibratedWhite"/>
+                            </view>
+                            <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" fixedFrame="YES" text="Knob Value: " textAlignment="center" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="iCj-20-bn8">
+                                <rect key="frame" x="231" y="38" width="179" height="21"/>
+                                <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
+                                <fontDescription key="fontDescription" name="Helvetica" family="Helvetica" pointSize="20"/>
+                                <color key="textColor" red="0.90196078431372551" green="0.53333333333333333" blue="0.0078431372549019607" alpha="1" colorSpace="custom" customColorSpace="displayP3"/>
+                                <nil key="highlightedColor"/>
+                            </label>
                         </subviews>
                         <color key="backgroundColor" red="0.21176470588235294" green="0.20784313725490194" blue="0.21568627450980393" alpha="1" colorSpace="custom" customColorSpace="displayP3"/>
                     </view>
                     <value key="contentSizeForViewInPopover" type="size" width="1024" height="337"/>
                     <freeformSimulatedSizeMetrics key="simulatedDestinationMetrics"/>
                     <size key="freeformSize" width="1024" height="337"/>
                     <connections>
-                        <outlet property="myKnob" destination="DJU-Fx-KsR" id="g8M-7f-yJE"/>
+                        <outlet property="displayLabel" destination="iCj-20-bn8" id="UtE-vd-65M"/>
+                        <outlet property="knobOne" destination="DJU-Fx-KsR" id="R5h-tc-9Hx"/>
+                        <outlet property="knobTwo" destination="7A7-28-Zh2" id="cJr-dX-jRB"/>
                     </connections>
                 </viewController>
                 <placeholder placeholderIdentifier="IBFirstResponder" id="dkx-z0-nzr" sceneMemberID="firstResponder"/>

SynthUISpike/ViewController.swift

@@ -10,22 +10,49 @@ import UIKit
 
 class ViewController: UIViewController {
 
-    @IBOutlet weak var myKnob: KnobView!
+    @IBOutlet weak var knobOne: KnobView!
+    @IBOutlet weak var knobTwo: KnobView!
+    @IBOutlet weak var displayLabel: UILabel!
+    
+    enum ControlTag: Int {
+        case control1 = 100
+        case control2 = 101
+    }
 
     override func viewDidLoad() {
         super.viewDidLoad()
         // Do any additional setup after loading the view, typically from a nib.
+        
+        knobOne.delegate = self
+        knobTwo.delegate = self
     }
 
-    override func didReceiveMemoryWarning() {
-        super.didReceiveMemoryWarning()
-        // Dispose of any resources that can be recreated.
-    }
+  
+}
 
-    @IBAction func mySlider(_ sender: UISlider) {
-        //myKnob.knobScale = CGFloat(sender.value) + 0.8
-        myKnob.value = Double(sender.value)
-    }
 
-}
+//*****************************************************************
+// MARK: - 🎛 Knob Delegate
+//*****************************************************************
 
+extension ViewController: KnobDelegate {
+    
+    func updateKnobValue(_ value: Double, tag: Int) {
+        
+        switch (tag) {
+            
+        // VCOs
+        case ControlTag.control1.rawValue:
+            let intValue = Int(floor(value * 10))
+            let message = "Knob One: \(intValue)"
+            displayLabel.text = message
+            
+        case ControlTag.control2.rawValue:
+            let message = "Knob Two: \(String(format: "%.02f", value))"
+            displayLabel.text = message
+            
+              default:
+            break
+        }
+    }
+}