Changes signature of private func base64DecodeBytes to accept collection of bytes which significantly simplifies callers

Author: valeriyvan

Sources/Foundation/NSData.swift

@@ -206,10 +206,7 @@ open class NSData : NSObject, NSCopying, NSMutableCopying, NSSecureCoding {
 
     /// Initializes a data object with the given Base64 encoded string.
     public init?(base64Encoded base64String: String, options: Base64DecodingOptions = []) {
-        guard var decodedBytes = base64String.utf8CString.withUnsafeBytes( { buffer -> [UInt8]? in
-            let bufferDroppingTerminatingNul = UnsafeRawBufferPointer(rebasing: buffer.dropLast())
-            return NSData.base64DecodeBytes(bufferDroppingTerminatingNul, options: options)
-        }) else {
+        guard var decodedBytes = NSData.base64DecodeBytes(base64String.utf8, options: options) else {
             return nil
         }
         super.init()
@@ -218,8 +215,7 @@ open class NSData : NSObject, NSCopying, NSMutableCopying, NSSecureCoding {
 
     /// Initializes a data object with the given Base64 encoded data.
     public init?(base64Encoded base64Data: Data, options: Base64DecodingOptions = []) {
-        guard var decodedBytes = base64Data
-            .withUnsafeBytes({ NSData.base64DecodeBytes($0, options: options) }) else {
+        guard var decodedBytes = NSData.base64DecodeBytes(base64Data, options: options) else {
             return nil
         }
         super.init()
@@ -671,7 +667,7 @@ open class NSData : NSObject, NSCopying, NSMutableCopying, NSSecureCoding {
      - parameter options:    Options for handling invalid input
      - returns:              The decoded bytes.
      */
-    private static func base64DecodeBytes(_ bytes: UnsafeRawBufferPointer, options: Base64DecodingOptions = []) -> [UInt8]? {
+    private static func base64DecodeBytes<T: Collection>(_ bytes: T, options: Base64DecodingOptions = []) -> [UInt8]? where T.Element == UInt8 {
         var decodedBytes = [UInt8]()
         decodedBytes.reserveCapacity((bytes.count/3)*2)