[stdlib] Add missing nullability to reflected NSString API

getBytes still lacks the ability to take an optional buffer, but Ali
agrees that we can leave that off for this release in light of the fact
that we have lengthOfBytesUsingEncoding.

Swift SVN r31223

stdlib/public/SDK/Foundation/NSStringAPI.swift

@@ -590,22 +590,49 @@ extension String {
   //     range:(NSRange)range
   //     remainingRange:(NSRangePointer)leftover
 
-  /// Gets a given range of characters as bytes in a specified encoding.
+  /// Writes the given `range` of characters into `buffer` in a given
+  /// `encoding`, without any allocations.  Does not NULL-terminate.
+  ///
+  /// - Parameter buffer: A buffer into which to store the bytes from
+  ///   the receiver. The returned bytes are not NUL-terminated.
+  ///
+  /// - Parameter maxBufferCount: The maximum number of bytes to write
+  ///   to buffer.
+  ///
+  /// - Parameter usedBufferCount: The number of bytes used from
+  ///   buffer. Pass `nil` if you do not need this value.
+  ///
+  /// - Parameter encoding: The encoding to use for the returned bytes.
+  ///
+  /// - Parameter options: A mask to specify options to use for
+  ///   converting the receiver’s contents to `encoding` (if conversion
+  ///   is necessary).
+  ///
+  /// - Parameter range: The range of characters in the receiver to get.
+  ///
+  /// - Parameter leftover: The remaining range. Pass `nil` If you do
+  ///   not need this value.
+  ///
+  /// - Returns: `true` iff some characters were converted.
+  ///
+  /// - Note: Conversion stops when the buffer fills or when the
+  ///   conversion isn't possible due to the chosen encoding.
+  ///
   /// - Note: will get a maximum of `min(buffer.count, maxLength)` bytes.
   public func getBytes(
     inout buffer: [UInt8],
-    maxLength: Int,
-    usedLength: UnsafeMutablePointer<Int>,
+    maxLength maxBufferCount: Int,
+    usedLength usedBufferCount: UnsafeMutablePointer<Int>,
     encoding: NSStringEncoding,
     options: NSStringEncodingConversionOptions,
     range: Range<Index>,
-    remainingRange: UnsafeMutablePointer<Range<Index>>
+    remainingRange leftover: UnsafeMutablePointer<Range<Index>>
   ) -> Bool {
-    return _withOptionalOutParameter(remainingRange) {
+    return _withOptionalOutParameter(leftover) {
       self._ns.getBytes(
         &buffer,
-        maxLength: min(buffer.count, maxLength),
-        usedLength: usedLength,
+        maxLength: min(buffer.count, maxBufferCount),
+        usedLength: usedBufferCount,
         encoding: encoding,
         options: options,
         range: _toNSRange(range),
@@ -1058,7 +1085,7 @@ extension String {
   /// converted to lowercase, taking into account the specified
   /// locale.
   @warn_unused_result
-  public func lowercaseStringWithLocale(locale: NSLocale) -> String {
+  public func lowercaseStringWithLocale(locale: NSLocale?) -> String {
     return _ns.lowercaseStringWithLocale(locale)
   }
 
@@ -1395,7 +1422,7 @@ extension String {
   /// applied.
   @warn_unused_result
   public func stringByFoldingWithOptions(
-    options: NSStringCompareOptions, locale: NSLocale
+    options: NSStringCompareOptions, locale: NSLocale?
   ) -> String {
     return _ns.stringByFoldingWithOptions(options, locale: locale)
   }
@@ -1558,7 +1585,7 @@ extension String {
   /// converted to uppercase, taking into account the specified
   /// locale.
   @warn_unused_result
-  public func uppercaseStringWithLocale(locale: NSLocale) -> String {
+  public func uppercaseStringWithLocale(locale: NSLocale?) -> String {
     return _ns.uppercaseStringWithLocale(locale)
   }