Made changes as per reviews

src/AudioUnit/AudioComponent.cs

@@ -52,21 +52,23 @@ public ResourceUsageInfo () : base () {}
 
 		public ResourceUsageInfo (NSDictionary dic) : base (dic) {}
 
-		public NSString[] IOKitUserClient { 
+		public string[] IOKitUserClient { 
 			get {
-				return GetArray<NSString> (userClientK);
+				var array = GetNativeValue<NSArray> (userClientK);
+				return NSArray.StringArrayFromHandle (array.ClassHandle);
 			} 
 			set {
-				SetArrayValue <NSString> (userClientK, value);
+				SetArrayValue (userClientK, value);
 			}
 		}
 
-		public NSString[] MachLookUpGlobalName { 
+		public string[] MachLookUpGlobalName { 
 			get {
-				return GetArray<NSString> (globalNameK);
+				var array = GetNativeValue<NSArray> (globalNameK);
+				return NSArray.StringArrayFromHandle (array.ClassHandle);
 			} 
 			set {
-				SetArrayValue <NSString> (globalNameK, value);
+				SetArrayValue (globalNameK, value);
 			}
 		}
 
@@ -392,7 +394,7 @@ public AudioComponentInfo[] ComponentList {
 					var cHandle = CopyComponentList (cfString.Handle);
 					if (cHandle == IntPtr.Zero)
 						return null;
-					using (var nsArray = Runtime.GetNSObject<NSArray> (cHandle)) {
+					using (var nsArray = Runtime.GetNSObject<NSArray> (cHandle, owns: true)) {
 						if (nsArray == null)
 							return null;
 						// make things easier for developers since we do not know how to have an implicit conversion from NSObject to AudioComponentInfo
@@ -421,7 +423,7 @@ public AudioComponentInfo[] ComponentList {
 						case AudioConverterError.None:
 							return;
 						default:
-							throw new InvalidOperationException ("ComponentList could not be set.");
+							throw new InvalidOperationException ($"ComponentList could not be set, error {result.ToString ()}");
 
 						}
 					}

src/AudioUnit/AudioUnit.cs

@@ -365,39 +365,39 @@ public enum AUParameterEventType : uint
 	[StructLayout (LayoutKind.Sequential)]
 	public struct AudioUnitParameterEvent
 	{
-		public uint scope;
-		public uint element;
-		public uint parameter;
-		public AUParameterEventType eventType;
+		public uint Scope;
+		public uint Element;
+		public uint Parameter;
+		public AUParameterEventType EventType;
 
 		[StructLayout (LayoutKind.Explicit)]
-		public struct EventValues
+		public struct EventValuesStruct
 		{
 			[StructLayout (LayoutKind.Sequential)]
-			public struct Ramp
+			public struct RampStruct
 			{
-				public int startBufferOffset;
-				public uint durationInFrames;
-				public float startValue;
-				public float endValue;
+				public int StartBufferOffset;
+				public uint DurationInFrames;
+				public float StartValue;
+				public float EndValue;
 			}
 
 
 			[FieldOffset (0)]
-			public Ramp ramp;
+			public RampStruct Ramp;
 
 			[StructLayout (LayoutKind.Sequential)]
-			public struct Immediate
+			public struct ImmediateStruct
 			{
-				public uint bufferOffset;
-				public float value;
+				public uint bBufferOffset;
+				public float Value;
 			}
 
 			[FieldOffset (0)]
-			public Immediate immediate;
+			public ImmediateStruct Immediate;
 		}
 
-		public EventValues eventValues;
+		public EventValuesStruct EventValues;
 	}
 
 	public class AudioUnit : IDisposable, XamCore.ObjCRuntime.INativeObject
@@ -1085,9 +1085,8 @@ static extern AudioUnitStatus AudioUnitGetPropertyInfo (IntPtr inUnit, AudioUnit
 		static extern AudioUnitStatus AudioUnitSetParameter (IntPtr inUnit, AudioUnitParameterType inID, AudioUnitScopeType inScope,
 			uint inElement, float inValue, uint inBufferOffsetInFrames);
 
-		[iOS (2,0)]
 		[DllImport (Constants.AudioUnitLibrary)]
-		static extern  AudioUnitStatus AudioUnitScheduleParameters (IntPtr inUnit, AudioUnitParameterEvent inParameterEvent, uint inNumParamEvents);
+		static extern AudioUnitStatus AudioUnitScheduleParameters (IntPtr inUnit, AudioUnitParameterEvent inParameterEvent, uint inNumParamEvents);
 
 #if MONOMAC
 		[DllImport (Constants.AudioUnitLibrary)]
@@ -2012,7 +2011,7 @@ public enum AUSpatializationAlgorithm : uint
 		SoundField = 3,
 		VectorBasedPanning = 4,
 		StereoPassThrough = 5,
-		HRTFHQ = 6,
+		HrtfHQ = 6,
 	}
 
 	public enum AU3DMixerAttenuationCurve : uint

src/audiounit.cs

@@ -8,6 +8,7 @@
 
 using System;
 using System.ComponentModel;
+using System.Runtime.InteropServices;
 
 using XamCore.AudioUnit;
 using XamCore.CoreFoundation;
@@ -40,7 +41,7 @@ internal delegate AudioUnitStatus AURenderPullInputBlock (ref AudioUnitRenderAct
 
 	delegate void AUScheduleParameterBlock (AUEventSampleTime eventSampleTime, uint rampDurationSampleFrames, ulong parameterAddress, float value);
 	[iOS (11, 0), Mac (10,13), TV (11,0), NoWatch]
-	delegate int AUMidiOutputEventBlock (long eventSampleTime, byte cable, nint length, ref byte midiBytes);
+	delegate int AUMidiOutputEventBlock (long eventSampleTime, byte cable, nint length, IntPtr midiBytes);
 	delegate void AUImplementorValueObserver (AUParameter param, float value);
 	delegate float AUImplementorValueProvider (AUParameter param);
 
@@ -263,11 +264,11 @@ interface AUAudioUnit_AUAudioInputOutputUnit {
 
 		[Mac (10,12), NoTV, NoiOS, NoWatch]
 		[Export ("deviceID")]
-		uint GetDeviceID ();
+		uint GetDeviceId ();
 
 		[Mac (10,12), NoTV, NoiOS, NoWatch]
 		[Export ("setDeviceID:error:")]
-		bool SetDeviceID (uint deviceID, out NSError outError);
+		bool SetDeviceId (uint deviceID, out NSError outError);
 
 		[Export ("canPerformInput")]
 		bool GetCanPerformInput ();

tests/monotouch-test/AudioToolbox/AudioComponentTest.cs

@@ -27,8 +27,7 @@ public class AudioComponentTest {
 		[Test]
 		public void GetSetComponentList ()
 		{
-			if (IntPtr.Size == 4)
-				Assert.Ignore ("API only available in 64 bits.");
+			TestRuntime.AssertXcodeVersion (9, 0);
 			var types = new List<AudioTypeOutput> { AudioTypeOutput.Generic, AudioTypeOutput.Remote, AudioTypeOutput.VoiceProcessingIO };
 			foreach (var t in types) {
 				var resources = new ResourceUsageInfo ();