Fix typos.

objective-c.html.markdown

@@ -288,7 +288,7 @@ int main (int argc, const char * argv[])
 // @property type name; <= property declarations.
 // -/+ (type) Method declarations; <= Method declarations. 
 // @end
-@interface MyClass : NSObject <MyProtocol> // NSObject is Objective-C base object class.
+@interface MyClass : NSObject <MyProtocol> // NSObject is Objective-C's base object class.
 {
     // Instance variable declarations (can exist in either interface or implementation file).
     int count; // Protected access by default. 
@@ -334,7 +334,7 @@ NSLog(@"%i", myClass.count); // prints => 45
     long distance; // Private access instance variable.
 }
 
-// To access public variable from the interface file, use '_' followed by variable name:
+// To access a public variable from the interface file, use '_' followed by variable name:
 _count = 5; // References "int count" from MyClass interface. 
 // Access variables defined in implementation file:
 distance = 18; // References "long distance" from MyClass implementation.