Add len_utf16 methods

Author: madsmtm

objc2/CHANGELOG_FOUNDATION.md

@@ -15,6 +15,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 * Added `NSNotFound`.
 * Added `NSBundle`.
 * Added `NSTimeInterval`.
+* Added `NSString::len_utf16` and `NSAttributedString::len_utf16`.
 
 
 ## objc2 0.3.0-beta.2 - 2022-08-28

objc2/src/foundation/attributed_string.rs

@@ -85,9 +85,7 @@ extern_methods!(
         /// Alias for `self.string().len_utf16()`.
         #[doc(alias = "length")]
         #[sel(length)]
-        #[allow(unused)]
-        // TODO: Finish this
-        fn len_utf16(&self) -> usize;
+        pub fn len_utf16(&self) -> usize;
 
         // /// TODO
         // ///

objc2/src/foundation/string.rs

@@ -63,13 +63,12 @@ extern_methods!(
             unsafe { msg_send![self, lengthOfBytesUsingEncoding: UTF8_ENCODING] }
         }
 
-        /// The number of UTF-16 code units in `self`.
+        /// The number of UTF-16 code units in the string.
         ///
         /// See also [`NSString::len`].
         #[doc(alias = "length")]
-        // TODO: Finish this
         #[sel(length)]
-        fn len_utf16(&self) -> usize;
+        pub fn len_utf16(&self) -> usize;
 
         pub fn is_empty(&self) -> bool {
             // TODO: lengthOfBytesUsingEncoding: might sometimes return 0 for