Add base85 extension to NSData

PiperOrigin-RevId: 731381576

internal/platform/implementation/apple/Mediums/BLEv2/NSData+GNCBase85.h

@@ -0,0 +1,35 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface NSData (GNCBase85)
+
+/** Creates a Base85 encoded string from the data using websafe characters and no padding. */
+- (NSString *)base85EncodedString;
+
+/**
+ * Initializes a data object with the given Base85 encoded string.
+ *
+ * @param base85String A Base85 encoded string.
+ * @return A data object built by Base85 decoding the provided string. Returns @c nil if the data
+ *         object could not be decoded.
+ */
+- (nullable instancetype)initWithBase85EncodedString:(NSString *)base85String;
+
+@end
+
+NS_ASSUME_NONNULL_END

internal/platform/implementation/apple/Mediums/BLEv2/NSData+GNCBase85.mm

@@ -0,0 +1,49 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#import "internal/platform/implementation/apple/Mediums/BLEv2/NSData+GNCBase85.h"
+
+#import <Foundation/Foundation.h>
+
+#include <optional>
+#include <string>
+
+#include "internal/encoding/base85.h"
+
+#import "GoogleToolboxForMac/GTMLogger.h"
+
+@implementation NSData (GNCBase85)
+
+- (NSString *)base85EncodedString {
+  const char *data = static_cast<const char *>(self.bytes);
+  NSUInteger length = self.length;
+  std::optional<std::string> base85String =
+      nearby::encoding::Base85Encode(std::string(data, length));
+  if (!base85String.has_value()) {
+    return @"";
+  }
+
+  return @(base85String->c_str());
+}
+
+- (nullable instancetype)initWithBase85EncodedString:(NSString *)base85String {
+  std::optional<std::string> decodedData =
+      nearby::encoding::Base85Decode(std::string(base85String.UTF8String));
+  if (!decodedData.has_value()) {
+    return nil;
+  }
+  return [NSData dataWithBytes:decodedData->data() length:decodedData->size()];
+}
+
+@end

internal/platform/implementation/apple/Mediums/BUILD

@@ -29,6 +29,7 @@ objc_library(
         "BLEv2/GNCCentralManager.m",
         "BLEv2/GNCPeripheral.m",
         "BLEv2/GNCPeripheralManager.m",
+        "BLEv2/NSData+GNCBase85.mm",
         "BLEv2/NSData+GNCWebSafeBase64.m",
         "Ble/GNCMBleConnection.m",
         "Ble/GNCMBleUtils.mm",
@@ -51,6 +52,7 @@ objc_library(
         "BLEv2/GNCCentralManager.h",
         "BLEv2/GNCPeripheral.h",
         "BLEv2/GNCPeripheralManager.h",
+        "BLEv2/NSData+GNCBase85.h",
         "BLEv2/NSData+GNCWebSafeBase64.h",
         "Ble/GNCMBleConnection.h",
         "Ble/GNCMBleUtils.h",
@@ -62,6 +64,7 @@ objc_library(
         "WiFiCommon/GNCNWFrameworkSocket.h",
     ],
     deps = [
+        "//internal/encoding:base85",
         "//internal/platform/implementation/apple:Shared",
         "//internal/platform/implementation/apple/Mediums/Ble/Sockets:Shared",
         "//proto/mediums:ble_frames_cc_proto",

internal/platform/implementation/apple/Tests/BUILD

@@ -44,6 +44,7 @@ objc_library(
         "GNCScheduledExecutorTest.mm",
         "GNCSingleThreadExecutorTest.mm",
         "GNCUtilsTest.mm",
+        "NSData+GNCBase85Test.m",
         "NSData+GNCWebSafeBase64Test.m",
     ],
     deps = [

internal/platform/implementation/apple/Tests/NSData+GNCBase85Test.m

@@ -0,0 +1,60 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#import "internal/platform/implementation/apple/Mediums/BLEv2/NSData+GNCBase85.h"
+
+#import <Foundation/Foundation.h>
+#import <XCTest/XCTest.h>
+
+@interface NSData_GNCBase85Test : XCTestCase
+@end
+
+@implementation NSData_GNCBase85Test
+
+- (void)testEncoding {
+  NSString *expected = @"@:E^";
+  NSData *data = [@"abc" dataUsingEncoding:NSUTF8StringEncoding];
+  NSString *actual = [data base85EncodedString];
+  XCTAssertEqualObjects(expected, actual);
+}
+
+- (void)testEncodingDataWithZero {
+  NSString *expected = @"z";
+  NSData *data = [@"\0\0" dataUsingEncoding:NSUTF8StringEncoding];
+  NSString *actual = [data base85EncodedString];
+  XCTAssertEqualObjects(expected, actual);
+}
+
+- (void)testDecoding {
+  NSData *data = [@"abc" dataUsingEncoding:NSUTF8StringEncoding];
+  NSString *actual = [data base85EncodedString];
+  NSData *decodedData = [[NSData alloc] initWithBase85EncodedString:actual];
+  XCTAssertEqualObjects(decodedData, data);
+}
+
+- (void)testEncodingEmptyData {
+  XCTAssertEqualObjects([[@"" dataUsingEncoding:NSUTF8StringEncoding] base85EncodedString], @"");
+}
+
+- (void)testDecodingEmptyData {
+  XCTAssertEqualObjects([[NSData alloc] initWithBase85EncodedString:@""],
+                        [@"" dataUsingEncoding:NSUTF8StringEncoding]);
+}
+
+- (void)testDecodingInvalidString {
+  NSString *invalidString = @"invalid";
+  XCTAssertNil([[NSData alloc] initWithBase85EncodedString:invalidString]);
+}
+
+@end