Added basic implementation for NSString contentsOfURL:usedEncoding:

Foundation/NSString.swift

@@ -1298,7 +1298,33 @@ extension NSString {
     }
 
     public convenience init(contentsOf url: URL, usedEncoding enc: UnsafeMutablePointer<UInt>?) throws {
-        NSUnimplemented()    
+        let readResult = try NSData(contentsOf: url, options:[])
+
+        let bytePtr = readResult.bytes.bindMemory(to: UInt8.self, capacity:readResult.length)
+        if readResult.length >= 2 && bytePtr[0] == 254 && bytePtr[1] == 255 {
+          enc?.pointee = String.Encoding.utf16BigEndian.rawValue
+        }
+        else if readResult.length >= 2 && bytePtr[0] == 255 && bytePtr[1] == 254 {
+          enc?.pointee = String.Encoding.utf16LittleEndian.rawValue
+        }
+        else {
+          //Need to work on more conditions. This should be the default
+          enc?.pointee = String.Encoding.utf8.rawValue
+        }
+
+        guard let enc = enc, let cf = CFStringCreateWithBytes(kCFAllocatorDefault, bytePtr, readResult.length, CFStringConvertNSStringEncodingToEncoding(enc.pointee), true) else {
+            throw NSError(domain: NSCocoaErrorDomain, code: CocoaError.fileReadInapplicableStringEncoding.rawValue, userInfo: [
+                "NSDebugDescription" : "Unable to create a string using the specified encoding."
+                ])
+        }
+        var str: String?
+        if String._conditionallyBridgeFromObjectiveC(cf._nsObject, result: &str) {
+            self.init(str!)
+        } else {
+            throw NSError(domain: NSCocoaErrorDomain, code: CocoaError.fileReadInapplicableStringEncoding.rawValue, userInfo: [
+                "NSDebugDescription" : "Unable to bridge CFString to String."
+                ])
+        }    
     }
 
     public convenience init(contentsOfFile path: String, usedEncoding enc: UnsafeMutablePointer<UInt>?) throws {

TestFoundation/TestNSString.swift

@@ -66,6 +66,8 @@ class TestNSString : XCTestCase {
             ("test_rangeOfCharacterFromSet", test_rangeOfCharacterFromSet ),
             ("test_CFStringCreateMutableCopy", test_CFStringCreateMutableCopy),
             ("test_FromContentsOfURL",test_FromContentsOfURL),
+            ("test_FromContentsOfURLUsedEncodingUTF16BE", test_FromContentsOfURLUsedEncodingUTF16BE),
+            ("test_FromContentsOfURLUsedEncodingUTF16LE", test_FromContentsOfURLUsedEncodingUTF16LE),
             ("test_FromContentOfFile",test_FromContentOfFile),
             ("test_swiftStringUTF16", test_swiftStringUTF16),
             // This test takes forever on build servers; it has been seen up to 1852.084 seconds
@@ -300,6 +302,38 @@ class TestNSString : XCTestCase {
         }
     }
 
+    func test_FromContentsOfURLUsedEncodingUTF16BE() {
+      guard let testFileURL = testBundle().url(forResource: "NSString-UTF16-BE-data", withExtension: "txt") else {
+        XCTFail("URL for NSString-UTF16-BE-data.txt is nil")
+        return
+      }
+
+      do {
+          var encoding: UInt = 0
+          let string = try NSString(contentsOf: testFileURL, usedEncoding: &encoding)
+          XCTAssertEqual(string, "NSString fromURL usedEncoding test with UTF16 BE file", "Wrong result when reading UTF16BE file")
+          XCTAssertEqual(encoding, String.Encoding.utf16BigEndian.rawValue, "Wrong encoding detected from UTF16BE file")
+      } catch {
+          XCTFail("Unable to init NSString from contentsOf:usedEncoding:")
+      }
+    }
+
+    func test_FromContentsOfURLUsedEncodingUTF16LE() {
+      guard let testFileURL = testBundle().url(forResource: "NSString-UTF16-LE-data", withExtension: "txt") else {
+        XCTFail("URL for NSString-UTF16-LE-data.txt is nil")
+        return
+      }
+
+      do {
+          var encoding: UInt = 0
+          let string = try NSString(contentsOf: testFileURL, usedEncoding: &encoding)
+          XCTAssertEqual(string, "NSString fromURL usedEncoding test with UTF16 LE file", "Wrong result when reading UTF16LE file")
+          XCTAssertEqual(encoding, String.Encoding.utf16LittleEndian.rawValue, "Wrong encoding detected from UTF16LE file")
+      } catch {
+          XCTFail("Unable to init NSString from contentOf:usedEncoding:")
+      }
+    }
+
     func test_FromContentOfFile() {
         let testFilePath = testBundle().path(forResource: "NSStringTestData", ofType: "txt")
         XCTAssertNotNil(testFilePath)

build.py

@@ -460,6 +460,8 @@
     'TestFoundation/Resources/NSURLTestData.plist',
     'TestFoundation/Resources/Test.plist',
     'TestFoundation/Resources/NSStringTestData.txt',
+    'TestFoundation/Resources/NSString-UTF16-BE-data.txt',
+    'TestFoundation/Resources/NSString-UTF16-LE-data.txt',
     'TestFoundation/Resources/NSXMLDocumentTestData.xml',
     'TestFoundation/Resources/PropertyList-1.0.dtd',
     'TestFoundation/Resources/NSXMLDTDTestData.xml',