id<GRXWriter> -> GRXWriter * in the runtime
diff --git a/src/objective-c/RxLibrary/GRXImmediateWriter.h b/src/objective-c/RxLibrary/GRXImmediateWriter.h
index f86d38d..0ba4ac4 100644
--- a/src/objective-c/RxLibrary/GRXImmediateWriter.h
+++ b/src/objective-c/RxLibrary/GRXImmediateWriter.h
@@ -44,11 +44,11 @@
// Returns a writer that pulls values from the passed NSEnumerator instance and pushes them to
// its writeable. The NSEnumerator is released when it finishes.
-+ (id<GRXWriter>)writerWithEnumerator:(NSEnumerator *)enumerator;
++ (GRXWriter *)writerWithEnumerator:(NSEnumerator *)enumerator;
// Returns a writer that pushes to its writeable the successive values returned by the passed
// block. When the block first returns nil, it is released.
-+ (id<GRXWriter>)writerWithValueSupplier:(id (^)())block;
++ (GRXWriter *)writerWithValueSupplier:(id (^)())block;
// Returns a writer that iterates over the values of the passed container and pushes them to
// its writeable. The container is released when the iteration is over.
@@ -56,18 +56,18 @@
// Note that the usual speed gain of NSFastEnumeration over NSEnumerator results from not having to
// call one method per element. Because GRXWriteable instances accept values one by one, that speed
// gain doesn't happen here.
-+ (id<GRXWriter>)writerWithContainer:(id<NSFastEnumeration>)container;
++ (GRXWriter *)writerWithContainer:(id<NSFastEnumeration>)container;
// Returns a writer that sends the passed value to its writeable and then finishes (releasing the
// value).
-+ (id<GRXWriter>)writerWithValue:(id)value;
++ (GRXWriter *)writerWithValue:(id)value;
// Returns a writer that, as part of its start method, sends the passed error to the writeable
// (then releasing the error).
-+ (id<GRXWriter>)writerWithError:(NSError *)error;
++ (GRXWriter *)writerWithError:(NSError *)error;
// Returns a writer that, as part of its start method, finishes immediately without sending any
// values to its writeable.
-+ (id<GRXWriter>)emptyWriter;
++ (GRXWriter *)emptyWriter;
@end