diff --git a/src/ObjectiveC/ObjCProxyCallback.class.st b/src/ObjectiveC/ObjCProxyCallback.class.st
index 6cac34f..28236ca 100644
--- a/src/ObjectiveC/ObjCProxyCallback.class.st
+++ b/src/ObjectiveC/ObjCProxyCallback.class.st
@@ -1,3 +1,7 @@
+"
+I'm a special callback, meant to implement proxy methods.
+ObjC will call Pharo using this callbacks.
+"
 Class {
 	#name : #ObjCProxyCallback,
 	#superclass : #FFICallback,
@@ -12,12 +16,25 @@ ObjCProxyCallback >> parseSignature: signature [
 	^ self newParser parseSignature: signature
 ]
 
+{ #category : #initialization }
+ObjCProxyCallback >> signature: signature block: aBlock [
+
+	super signature: signature block: aBlock.
+	functionSpec arguments: { 
+		ObjCProxyCallbackArgument new. "receiver"
+		ObjCProxyCallbackArgument new. "selector"
+	 }, 
+	functionSpec arguments.
+
+]
+
 { #category : #evaluation }
 ObjCProxyCallback >> valueWithArguments: args [
 
-	^ [ 
-			"skip self, SEL and keep just the arguments"
-			block value: (args allButFirst: 2) ]
+	^ [ block 
+			value: args first 
+			value: args second
+			value: (args allButFirst: 2) ]
 		on: Error 
 		fork: [ :e | e debug ]
 		return: [ self returnOnError ]
diff --git a/src/ObjectiveC/ObjCProxyCallbackArgument.class.st b/src/ObjectiveC/ObjCProxyCallbackArgument.class.st
new file mode 100644
index 0000000..ce3a48a
--- /dev/null
+++ b/src/ObjectiveC/ObjCProxyCallbackArgument.class.st
@@ -0,0 +1,52 @@
+"
+I'm a function argument type to be used on the declaration of proxy methods. 
+I am needed because in ObjC every method implementation has the same structure: 
+
+id (*IMP)(receiver, selector, ...)
+
+https://developer.apple.com/documentation/objectivec/objective-c_runtime/imp
+
+being the first two arguments the receiver and the selector.
+this is internally converted to a send of the form 
+
+receiver selector: arg 
+
+(a call with the arguments).
+
+To match a regular send, we need to add this arguments to the callback, but they are hidden to the user.
+
+
+"
+Class {
+	#name : #ObjCProxyCallbackArgument,
+	#superclass : #FFIFunctionArgument,
+	#traits : 'TObjCLibrary',
+	#classTraits : 'TObjCLibrary classTrait',
+	#category : #'ObjectiveC-Proxy'
+}
+
+{ #category : #resolution }
+ObjCProxyCallbackArgument >> asOldArraySpec [
+
+	^ #()
+]
+
+{ #category : #initialization }
+ObjCProxyCallbackArgument >> initialize [
+
+	super initialize.
+	type := ObjCTypeDeclaration newType: (FFIVoid new 
+		pointerArity: 1;
+		yourself)
+]
+
+{ #category : #resolution }
+ObjCProxyCallbackArgument >> resolveUsing: aResolver [
+	"Do nothing"
+]
+
+{ #category : #initialization }
+ObjCProxyCallbackArgument >> resolvedType [
+
+	^ type resolvedType
+]
diff --git a/src/ObjectiveC/ObjCProxyClass.class.st b/src/ObjectiveC/ObjCProxyClass.class.st
index cb97f8f..b33218b 100644
--- a/src/ObjectiveC/ObjCProxyClass.class.st
+++ b/src/ObjectiveC/ObjCProxyClass.class.st
@@ -1,3 +1,6 @@
+"
+I define a class that will be installed in ObjC and will work as a proxy between ObjC and Pharo
+"
 Class {
 	#name : #ObjCProxyClass,
 	#superclass : #Object,
@@ -95,7 +98,7 @@ ObjCProxyClass >> class_addMethodClass: cls selector: name implementation: imp s
 { #category : #private }
 ObjCProxyClass >> createCallbackFor: aSelector signature: aString [
 
-	^ ObjCProxyCallback 
+	^ ObjCProxyCallback
 		signature: aString
 		block: [ :receiver :ignoredSelector :args | 
 			self 
diff --git a/src/ObjectiveC/ObjCProxyObject.class.st b/src/ObjectiveC/ObjCProxyObject.class.st
index fbdc28e..0e657c7 100644
--- a/src/ObjectiveC/ObjCProxyObject.class.st
+++ b/src/ObjectiveC/ObjCProxyObject.class.st
@@ -9,9 +9,6 @@ Class {
 	#superclass : #Object,
 	#traits : 'TObjCProxyClass',
 	#classTraits : 'TObjCProxyClass classTrait',
-	#instVars : [
-		'proxy'
-	],
 	#category : #'ObjectiveC-Proxy'
 }
 
@@ -32,13 +29,3 @@ ObjCProxyObject >> initialize [
 ObjCProxyObject >> initializeProxy [
 	
 ]
-
-{ #category : #accessing }
-ObjCProxyObject >> proxy [
-	^ proxy
-]
-
-{ #category : #accessing }
-ObjCProxyObject >> proxy: anObject [
-	proxy := anObject.
-]
diff --git a/src/ObjectiveC/ObjCTypeDeclaration.class.st b/src/ObjectiveC/ObjCTypeDeclaration.class.st
index f6e1ccb..79b0b69 100644
--- a/src/ObjectiveC/ObjCTypeDeclaration.class.st
+++ b/src/ObjectiveC/ObjCTypeDeclaration.class.st
@@ -1,3 +1,7 @@
+"
+I'm a type declaration for ObjC functions. 
+I'm needed because when matching ObjC functions I already have all needed data, so I can skip the resolution of type.
+"
 Class {
 	#name : #ObjCTypeDeclaration,
 	#superclass : #FFITypeDeclaration,