Compile rtc_api_objc on Mac.

webrtc/api/objc/RTCIceServer.mm

 /*
  *  Copyright 2015 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #import "RTCIceServer.h"
 
 #import "webrtc/api/objc/RTCIceServer+Private.h"
 #import "webrtc/base/objc/NSString+StdString.h"
 
 @implementation RTCIceServer
+// TODO(hjon): Update nullability types. See http://crbug/webrtc/5592
 
 @synthesize urlStrings = _urlStrings;
 @synthesize username = _username;
 @synthesize credential = _credential;
 
-- (instancetype)initWithURLStrings:(NSArray<NSString *> *)urlStrings {
+- (instancetype)initWithURLStrings:(NSArray *)urlStrings {
+// - (instancetype)initWithURLStrings:(NSArray<NSString *> *)urlStrings {
   NSParameterAssert(urlStrings.count);
   return [self initWithURLStrings:urlStrings
                          username:nil
                        credential:nil];
 }
 
-- (instancetype)initWithURLStrings:(NSArray<NSString *> *)urlStrings
+- (instancetype)initWithURLStrings:(NSArray *)urlStrings
+// - (instancetype)initWithURLStrings:(NSArray<NSString *> *)urlStrings
                           username:(NSString *)username
                         credential:(NSString *)credential {
   NSParameterAssert(urlStrings.count);
   if (self = [super init]) {
     _urlStrings = [[NSArray alloc] initWithArray:urlStrings copyItems:YES];
     _username = [username copy];
     _credential = [credential copy];
   }
   return self;
 }
@@ skipping 30 matching lines @@
   }
   NSString *username = [NSString stringForStdString:nativeServer.username];
   NSString *credential = [NSString stringForStdString:nativeServer.password];
   self = [self initWithURLStrings:urls
                          username:username
                        credential:credential];
   return self;
 }
 
 @end