Obj-C SDK for parsing and generating H264 ProfileLevelIds.

Expose this functionality in the Obj-C SDK to make it nicer to use for
Obj-C clients.

Bug: None
Change-Id: I5cb511af8799ac0fda15153d16f2550b848b93b2
Reviewed-on: https://webrtc-review.googlesource.com/80481
Reviewed-by: Peter Hanspers <peterhanspers@webrtc.org>
Commit-Queue: Anders Carlsson <andersc@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23488}

sdk/objc/Framework/Classes/PeerConnection/RTCH264ProfileLevelId.mm

@@ -0,0 +1,58 @@
+/*
+ *  Copyright 2018 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 "WebRTC/RTCVideoCodecH264.h"
+
+#include "media/base/h264_profile_level_id.h"
+
+@interface RTCH264ProfileLevelId ()
+
+@property(nonatomic, assign) RTCH264Profile profile;
+@property(nonatomic, assign) RTCH264Level level;
+@property(nonatomic, strong) NSString *hexString;
+
+@end
+
+@implementation RTCH264ProfileLevelId
+
+@synthesize profile = _profile;
+@synthesize level = _level;
+@synthesize hexString = _hexString;
+
+- (instancetype)initWithHexString:(NSString *)hexString {
+  if (self = [super init]) {
+    self.hexString = hexString;
+
+    rtc::Optional<webrtc::H264::ProfileLevelId> profile_level_id =
+        webrtc::H264::ParseProfileLevelId([hexString cStringUsingEncoding:NSUTF8StringEncoding]);
+    if (profile_level_id.has_value()) {
+      self.profile = static_cast<RTCH264Profile>(profile_level_id->profile);
+      self.level = static_cast<RTCH264Level>(profile_level_id->level);
+    }
+  }
+  return self;
+}
+
+- (instancetype)initWithProfile:(RTCH264Profile)profile level:(RTCH264Level)level {
+  if (self = [super init]) {
+    self.profile = profile;
+    self.level = level;
+
+    rtc::Optional<std::string> hex_string =
+        webrtc::H264::ProfileLevelIdToString(webrtc::H264::ProfileLevelId(
+            static_cast<webrtc::H264::Profile>(profile), static_cast<webrtc::H264::Level>(level)));
+    self.hexString =
+        [NSString stringWithCString:hex_string.value_or("").c_str() encoding:NSUTF8StringEncoding];
+  }
+  return self;
+}
+
+@end