Removed as_ref and the core feature.

Author: SSheldon

src/array.rs

@@ -71,14 +71,14 @@ pub trait INSArray : INSObject {
     fn first_object(&self) -> Option<&Self::Item> {
         unsafe {
             let obj: *const Self::Item = msg_send![self, firstObject];
-            obj.as_ref()
+            if obj.is_null() { None } else { Some(&*obj) }
         }
     }
 
     fn last_object(&self) -> Option<&Self::Item> {
         unsafe {
             let obj: *const Self::Item = msg_send![self, lastObject];
-            obj.as_ref()
+            if obj.is_null() { None } else { Some(&*obj) }
         }
     }
 

src/dictionary.rs

@@ -25,7 +25,7 @@ pub trait INSDictionary : INSObject {
     fn object_for(&self, key: &Self::Key) -> Option<&Self::Value> {
         unsafe {
             let obj: *mut Self::Value = msg_send![self, objectForKey:key];
-            obj.as_ref()
+            if obj.is_null() { None } else { Some(&*obj) }
         }
     }
 

src/enumerator.rs

@@ -26,7 +26,7 @@ impl<'a, T> Iterator for NSEnumerator<'a, T> where T: INSObject {
     fn next(&mut self) -> Option<&'a T> {
         unsafe {
             let obj: *mut T = msg_send![self.id, nextObject];
-            obj.as_ref()
+            if obj.is_null() { None } else { Some(&*obj) }
         }
     }
 }

src/lib.rs

@@ -1,8 +1,6 @@
 #![crate_name = "objc_foundation"]
 #![crate_type = "lib"]
 
-#![feature(core)]
-
 extern crate libc;
 #[macro_use]
 extern crate objc;