Pass around the candidate removals events in IOS clients

webrtc/examples/objc/AppRTCDemo/RTCICECandidate+JSON.m

Index: webrtc/examples/objc/AppRTCDemo/RTCICECandidate+JSON.m
diff --git a/webrtc/examples/objc/AppRTCDemo/RTCICECandidate+JSON.m b/webrtc/examples/objc/AppRTCDemo/RTCICECandidate+JSON.m
index f20c490682a3410e8894ae07b8f6ef263faf8f00..b1be7fb7e3cb995353768041d15cca94e789cdf8 100644
--- a/webrtc/examples/objc/AppRTCDemo/RTCICECandidate+JSON.m
+++ b/webrtc/examples/objc/AppRTCDemo/RTCICECandidate+JSON.m
@@ -17,6 +17,8 @@ static NSString const *kRTCICECandidateTypeValue = @"candidate";
 static NSString const *kRTCICECandidateMidKey = @"id";
 static NSString const *kRTCICECandidateMLineIndexKey = @"label";
 static NSString const *kRTCICECandidateSdpKey = @"candidate";
+static NSString const *kRTCICECandidatesTypeKey = @"candidates";
+
 
 @implementation RTCIceCandidate (JSON)
 
@@ -30,6 +32,43 @@ static NSString const *kRTCICECandidateSdpKey = @"candidate";
                                        sdpMid:mid];
 }
 
++ (NSData *)JSONDataForIceCandidates:(NSArray<RTCIceCandidate *> *)candidates
+                            withType:(NSString *)typeValue {
+  NSMutableArray *jsonCandidates =
+      [NSMutableArray arrayWithCapacity:candidates.count];
+  for (RTCIceCandidate *candidate in candidates) {
+    NSDictionary *jsonCandidate = [candidate JSONDictionary];
+    [jsonCandidates addObject:jsonCandidate];
+  }
+  NSDictionary *json = @{
+    kRTCICECandidateTypeKey : typeValue,
+    kRTCICECandidatesTypeKey : jsonCandidates
+  };
+  NSError *error = nil;
+  NSData *data =
+      [NSJSONSerialization dataWithJSONObject:json
+                                      options:NSJSONWritingPrettyPrinted
+                                        error:&error];
+  if (error) {
+    RTCLogError(@"Error serializing JSON: %@", error);
+    return nil;
+  }
+  return data;
+}
+
++ (NSArray<RTCIceCandidate *> *)candidatesFromJSONDictionary:
+    (NSDictionary *)dictionary {
+  NSArray *jsonCandidates = dictionary[kRTCICECandidatesTypeKey];
+  NSMutableArray<RTCIceCandidate *> *candidates =
+      [NSMutableArray arrayWithCapacity:jsonCandidates.count];
+  for (NSDictionary *jsonCandidate in jsonCandidates) {
+    RTCIceCandidate *candidate =
+        [RTCIceCandidate candidateFromJSONDictionary:jsonCandidate];
+    [candidates addObject:candidate];
+  }
+  return candidates;
+}
+
 - (NSData *)JSONData {
   NSDictionary *json = @{
     kRTCICECandidateTypeKey : kRTCICECandidateTypeValue,
@@ -49,4 +88,13 @@ static NSString const *kRTCICECandidateSdpKey = @"candidate";
   return data;
 }
 
+- (NSDictionary *)JSONDictionary{
+  NSDictionary *json = @{
+    kRTCICECandidateMLineIndexKey : @(self.sdpMLineIndex),
+    kRTCICECandidateMidKey : self.sdpMid,
+    kRTCICECandidateSdpKey : self.sdp
+  };
+  return json;
+}
+
 @end