Foundation overlay: add String.stringByApplyingTransform()

This API is new in OS X 10.11 and iOS 9.0.

rdar://20645458

Swift SVN r28257

stdlib/public/SDK/Foundation/NSStringAPI.swift

@@ -1468,5 +1468,13 @@ extension String {
     try self._ns.writeToURL(
       url, atomically: useAuxiliaryFile, encoding: enc)
   }
+
+  @availability(iOS, introduced=9.0)
+  @availability(OSX, introduced=10.11)
+  public func stringByApplyingTransform(
+    transform: String, reverse: Bool
+  ) -> String? {
+    return _ns.stringByApplyingTransform(transform, reverse: reverse)
+  }
 }
 

test/1_stdlib/NSStringAPI.swift

@@ -1583,6 +1583,32 @@ NSStringAPIs.test("writeToURL(_:atomically:encoding:error:)") {
   }
 }
 
+NSStringAPIs.test("stringByApplyingTransform(_:reverse:)") {
+  if #available(OSX 10.11, iOS 9.0, *) {
+    if true {
+      let source = "tre\u{300}s k\u{fc}hl"
+      expectEqual(
+        "tres kuhl",
+        source.stringByApplyingTransform(
+          NSStringTransformStripDiacritics, reverse: false))
+    }
+    if true {
+      let source = "hiragana"
+      expectEqual(
+        "ひらがな",
+        source.stringByApplyingTransform(
+          NSStringTransformLatinToHiragana, reverse: false))
+    }
+    if true {
+      let source = "ひらがな"
+      expectEqual(
+        "hiragana",
+        source.stringByApplyingTransform(
+          NSStringTransformLatinToHiragana, reverse: true))
+    }
+  }
+}
+
 struct ComparisonTest {
   let expectedUnicodeCollation: ExpectedComparisonResult
   let lhs: String