Make a friendlier RTCVideoCodecInfo initializer.

webrtc/sdk/objc/Framework/Classes/PeerConnection/RTCVideoCodec.mm

 /*
  *  Copyright 2017 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/RTCVideoCodec.h"
 
 #import "NSString+StdString.h"
 #import "RTCVideoCodec+Private.h"
 #import "WebRTC/RTCVideoCodecFactory.h"
 
 @implementation RTCVideoCodecInfo
 
 @synthesize payload = _payload;
 @synthesize name = _name;
 @synthesize parameters = _parameters;
 
-- (instancetype)initWithPayload:(NSInteger)payload
-                           name:(NSString *)name
-                     parameters:(NSDictionary<NSString *, NSString *> *)parameters {
+- (instancetype)initWithName:(NSString *)name
+                  parameters:(nullable NSDictionary<NSString *, NSString *> *)parameters {
   if (self = [super init]) {
-    _payload = payload;
+    _payload = 0;
     _name = name;
-    _parameters = parameters;
+    _parameters = (parameters ? parameters : @{});
   }
 
   return self;
 }
 
 - (instancetype)initWithNativeVideoCodec:(cricket::VideoCodec)videoCodec {
   NSMutableDictionary *params = [NSMutableDictionary dictionary];
   for (auto it = videoCodec.params.begin(); it != videoCodec.params.end(); ++it) {
     [params setObject:[NSString stringForStdString:it->second]
                forKey:[NSString stringForStdString:it->first]];
   }
   return [self initWithPayload:videoCodec.id
                           name:[NSString stringForStdString:videoCodec.name]
                     parameters:params];
 }
 
+- (instancetype)initWithPayload:(NSInteger)payload
+                           name:(NSString *)name
+                     parameters:(NSDictionary<NSString *, NSString *> *)parameters {
+  if (self = [self initWithName:name parameters:parameters]) {
+    _payload = payload;
+  }
+
+  return self;
+}
+
 - (cricket::VideoCodec)nativeVideoCodec {
   cricket::VideoCodec codec([NSString stdStringForString:_name]);
   for (NSString *paramKey in _parameters.allKeys) {
     codec.SetParam([NSString stdStringForString:paramKey],
                    [NSString stdStringForString:_parameters[paramKey]]);
   }
 
   return codec;
 }
 
 @end
 
 @implementation RTCVideoEncoderQpThresholds
 
 @synthesize low = _low;
 @synthesize high = _high;
 
 - (instancetype)initWithThresholdsLow:(NSInteger)low high:(NSInteger)high {
   if (self = [super init]) {
     _low = low;
     _high = high;
   }
   return self;
 }
 
 @end