diff --git a/sdk/objc/api/peerconnection/RTCPeerConnection.h b/sdk/objc/api/peerconnection/RTCPeerConnection.h
index 77a8dccac1..d0cd99ce74 100644
--- a/sdk/objc/api/peerconnection/RTCPeerConnection.h
+++ b/sdk/objc/api/peerconnection/RTCPeerConnection.h
@@ -81,6 +81,12 @@ typedef NS_ENUM(NSInteger, RTCStatsOutputLevel) {
   RTCStatsOutputLevelDebug,
 };
 
+typedef void (^RTCCreateSessionDescriptionCompletionHandler)(RTC_OBJC_TYPE(RTCSessionDescription) *
+                                                                 _Nullable sdp,
+                                                             NSError *_Nullable error);
+
+typedef void (^RTCSetSessionDescriptionCompletionHandler)(NSError *_Nullable error);
+
 @class RTC_OBJC_TYPE(RTCPeerConnection);
 
 RTC_OBJC_EXPORT
@@ -293,27 +299,24 @@ RTC_OBJC_EXPORT
 
 /** Generate an SDP offer. */
 - (void)offerForConstraints:(RTC_OBJC_TYPE(RTCMediaConstraints) *)constraints
-          completionHandler:(nullable void (^)(RTC_OBJC_TYPE(RTCSessionDescription) * _Nullable sdp,
-                                               NSError *_Nullable error))completionHandler;
+          completionHandler:(RTCCreateSessionDescriptionCompletionHandler)completionHandler;
 
 /** Generate an SDP answer. */
 - (void)answerForConstraints:(RTC_OBJC_TYPE(RTCMediaConstraints) *)constraints
-           completionHandler:
-               (nullable void (^)(RTC_OBJC_TYPE(RTCSessionDescription) * _Nullable sdp,
-                                  NSError *_Nullable error))completionHandler;
+           completionHandler:(RTCCreateSessionDescriptionCompletionHandler)completionHandler;
 
 /** Apply the supplied RTCSessionDescription as the local description. */
 - (void)setLocalDescription:(RTC_OBJC_TYPE(RTCSessionDescription) *)sdp
-          completionHandler:(nullable void (^)(NSError *_Nullable error))completionHandler;
+          completionHandler:(RTCSetSessionDescriptionCompletionHandler)completionHandler;
 
 /** Creates an offer or answer (depending on current signaling state) and sets
  * it as the local session description. */
 - (void)setLocalDescriptionWithCompletionHandler:
-    (nullable void (^)(NSError *_Nullable error))completionHandler;
+    (RTCSetSessionDescriptionCompletionHandler)completionHandler;
 
 /** Apply the supplied RTCSessionDescription as the remote description. */
 - (void)setRemoteDescription:(RTC_OBJC_TYPE(RTCSessionDescription) *)sdp
-           completionHandler:(nullable void (^)(NSError *_Nullable error))completionHandler;
+           completionHandler:(RTCSetSessionDescriptionCompletionHandler)completionHandler;
 
 /** Limits the bandwidth allocated for all RTP streams sent by this
  *  PeerConnection. Nil parameters will be unchanged. Setting
diff --git a/sdk/objc/api/peerconnection/RTCPeerConnection.mm b/sdk/objc/api/peerconnection/RTCPeerConnection.mm
index e3ab65ae30..3cc714b238 100644
--- a/sdk/objc/api/peerconnection/RTCPeerConnection.mm
+++ b/sdk/objc/api/peerconnection/RTCPeerConnection.mm
@@ -37,33 +37,26 @@
 NSString *const kRTCPeerConnectionErrorDomain = @"org.webrtc.RTC_OBJC_TYPE(RTCPeerConnection)";
 int const kRTCPeerConnnectionSessionDescriptionError = -1;
 
-typedef void (^RTCSetSessionDescriptionCompletionHandler)(NSError *_Nullable error);
-
 namespace {
 
 class SetSessionDescriptionObserver : public webrtc::SetLocalDescriptionObserverInterface,
                                       public webrtc::SetRemoteDescriptionObserverInterface {
  public:
-  SetSessionDescriptionObserver(
-      RTCSetSessionDescriptionCompletionHandler _Nullable completionHandler) {
+  SetSessionDescriptionObserver(RTCSetSessionDescriptionCompletionHandler completionHandler) {
     completion_handler_ = completionHandler;
   }
 
   virtual void OnSetLocalDescriptionComplete(webrtc::RTCError error) override {
-    if (completion_handler_ != nil) {
-      OnCompelete(error);
-    }
+    OnCompelete(error);
   }
 
   virtual void OnSetRemoteDescriptionComplete(webrtc::RTCError error) override {
-    if (completion_handler_ != nil) {
-      OnCompelete(error);
-    }
+    OnCompelete(error);
   }
 
  private:
   void OnCompelete(webrtc::RTCError error) {
-    RTC_DCHECK(completion_handler_);
+    RTC_DCHECK(completion_handler_ != nil);
     if (error.ok()) {
       completion_handler_(nil);
     } else {
@@ -542,8 +535,8 @@ void PeerConnectionDelegateAdapter::OnRemoveTrack(
 }
 
 - (void)offerForConstraints:(RTC_OBJC_TYPE(RTCMediaConstraints) *)constraints
-          completionHandler:(void (^)(RTC_OBJC_TYPE(RTCSessionDescription) * sessionDescription,
-                                      NSError *error))completionHandler {
+          completionHandler:(RTCCreateSessionDescriptionCompletionHandler)completionHandler {
+  RTC_DCHECK(completionHandler != nil);
   rtc::scoped_refptr<webrtc::CreateSessionDescriptionObserverAdapter>
       observer(new rtc::RefCountedObject
           <webrtc::CreateSessionDescriptionObserverAdapter>(completionHandler));
@@ -554,8 +547,8 @@ void PeerConnectionDelegateAdapter::OnRemoveTrack(
 }
 
 - (void)answerForConstraints:(RTC_OBJC_TYPE(RTCMediaConstraints) *)constraints
-           completionHandler:(void (^)(RTC_OBJC_TYPE(RTCSessionDescription) * sessionDescription,
-                                       NSError *error))completionHandler {
+           completionHandler:(RTCCreateSessionDescriptionCompletionHandler)completionHandler {
+  RTC_DCHECK(completionHandler != nil);
   rtc::scoped_refptr<webrtc::CreateSessionDescriptionObserverAdapter>
       observer(new rtc::RefCountedObject
           <webrtc::CreateSessionDescriptionObserverAdapter>(completionHandler));
@@ -566,21 +559,24 @@ void PeerConnectionDelegateAdapter::OnRemoveTrack(
 }
 
 - (void)setLocalDescription:(RTC_OBJC_TYPE(RTCSessionDescription) *)sdp
-          completionHandler:(nullable void (^)(NSError *error))completionHandler {
+          completionHandler:(RTCSetSessionDescriptionCompletionHandler)completionHandler {
+  RTC_DCHECK(completionHandler != nil);
   rtc::scoped_refptr<webrtc::SetLocalDescriptionObserverInterface> observer(
       new rtc::RefCountedObject<::SetSessionDescriptionObserver>(completionHandler));
   _peerConnection->SetLocalDescription(sdp.nativeDescription->Clone(), observer);
 }
 
 - (void)setLocalDescriptionWithCompletionHandler:
-    (nullable void (^)(NSError *error))completionHandler {
+    (RTCSetSessionDescriptionCompletionHandler)completionHandler {
+  RTC_DCHECK(completionHandler != nil);
   rtc::scoped_refptr<webrtc::SetLocalDescriptionObserverInterface> observer(
       new rtc::RefCountedObject<::SetSessionDescriptionObserver>(completionHandler));
   _peerConnection->SetLocalDescription(observer);
 }
 
 - (void)setRemoteDescription:(RTC_OBJC_TYPE(RTCSessionDescription) *)sdp
-           completionHandler:(nullable void (^)(NSError *error))completionHandler {
+           completionHandler:(RTCSetSessionDescriptionCompletionHandler)completionHandler {
+  RTC_DCHECK(completionHandler != nil);
   rtc::scoped_refptr<webrtc::SetRemoteDescriptionObserverInterface> observer(
       new rtc::RefCountedObject<::SetSessionDescriptionObserver>(completionHandler));
   _peerConnection->SetRemoteDescription(sdp.nativeDescription->Clone(), observer);