Removes creating intermediate objects in base64 decoding

Author: valeriyvan

Sources/Foundation/NSData.swift

@@ -206,8 +206,10 @@ open class NSData : NSObject, NSCopying, NSMutableCopying, NSSecureCoding {
 
     /// Initializes a data object with the given Base64 encoded string.
     public init?(base64Encoded base64String: String, options: Base64DecodingOptions = []) {
-        let encodedBytes = Array(base64String.utf8)
-        guard var decodedBytes = NSData.base64DecodeBytes(encodedBytes, options: options) else {
+        guard var decodedBytes = base64String.utf8CString.withUnsafeBytes( { buffer -> [UInt8]? in
+            let bufferDroppingTerminatingNul = UnsafeRawBufferPointer(rebasing: buffer.dropLast())
+            return NSData.base64DecodeBytes(bufferDroppingTerminatingNul, options: options)
+        }) else {
             return nil
         }
         super.init()
@@ -216,9 +218,8 @@ open class NSData : NSObject, NSCopying, NSMutableCopying, NSSecureCoding {
 
     /// Initializes a data object with the given Base64 encoded data.
     public init?(base64Encoded base64Data: Data, options: Base64DecodingOptions = []) {
-        var encodedBytes = [UInt8](repeating: 0, count: base64Data.count)
-        base64Data._nsObject.getBytes(&encodedBytes, length: encodedBytes.count)
-        guard var decodedBytes = NSData.base64DecodeBytes(encodedBytes, options: options) else {
+        guard var decodedBytes = base64Data
+            .withUnsafeBytes({ NSData.base64DecodeBytes($0, options: options) }) else {
             return nil
         }
         super.init()
@@ -670,7 +671,7 @@ open class NSData : NSObject, NSCopying, NSMutableCopying, NSSecureCoding {
      - parameter options:    Options for handling invalid input
      - returns:              The decoded bytes.
      */
-    private static func base64DecodeBytes(_ bytes: [UInt8], options: Base64DecodingOptions = []) -> [UInt8]? {
+    private static func base64DecodeBytes(_ bytes: UnsafeRawBufferPointer, options: Base64DecodingOptions = []) -> [UInt8]? {
         var decodedBytes = [UInt8]()
         decodedBytes.reserveCapacity((bytes.count/3)*2)