Added missing ivar access functions.

ivar.c

@@ -108,3 +108,36 @@ PRIVATE void objc_compute_ivar_offsets(Class class)
 		abort();
 	}
 }
+
+////////////////////////////////////////////////////////////////////////////////
+// Public API functions
+////////////////////////////////////////////////////////////////////////////////
+
+void object_setIvar(id object, Ivar ivar, id value)
+{
+	char *addr = (char*)&object;
+	addr += ivar_getOffset(ivar);
+	*(id*)addr = value;
+}
+
+Ivar object_setInstanceVariable(id obj, const char *name, void *value)
+{
+	Ivar ivar = class_getInstanceVariable(object_getClass(obj), name);
+	object_setIvar(obj, ivar, value);
+	return ivar;
+}
+
+id object_getIvar(id object, Ivar ivar)
+{
+	return *(id*)(((char*)&object) + ivar_getOffset(ivar));
+}
+
+Ivar object_getInstanceVariable(id obj, const char *name, void **outValue)
+{
+	Ivar ivar = class_getInstanceVariable(object_getClass(obj), name);
+	if (NULL != outValue)
+	{
+		*outValue = object_getIvar(obj, ivar);
+	}
+	return ivar;
+}

objc/runtime.h

@@ -266,6 +266,30 @@ size_t class_getInstanceSize(Class cls);
  */
 Ivar class_getInstanceVariable(Class cls, const char* name);
 
+/**
+ * Sets the object value of a specified instance variable.
+ */
+void object_setIvar(id object, Ivar ivar, id value);
+/**
+ * Sets a named instance variable to the value specified by *value.  Note that
+ * the instance variable must be a pointer-sized quantity.
+ */
+Ivar object_setInstanceVariable(id obj, const char *name, void *value);
+
+/**
+ * Returns the value of the named instance variable.  This should not be used
+ * with instance variables that are not pointers.
+ */
+id object_getIvar(id object, Ivar ivar);
+
+/**
+ * Returns a named instance variable via the final parameter.  Note that
+ * calling object_getIvar() on the value returned from this function is faster.
+ *
+ * Note that the instance variable must be a pointer-sized quantity.
+ */
+Ivar object_getInstanceVariable(id obj, const char *name, void **outValue);
+
 /**
  * Returns a pointer to the function used to handle the specified message.  If
  * the receiver does not have a method corresponding to this message then this