diff --git a/src/objective-c/GRPCClient/GRPCCall.h b/src/objective-c/GRPCClient/GRPCCall.h
index 214969af230..51a82263bff 100644
--- a/src/objective-c/GRPCClient/GRPCCall.h
+++ b/src/objective-c/GRPCClient/GRPCCall.h
@@ -282,6 +282,8 @@ NS_ASSUME_NONNULL_END
  */
 @interface GRPCCall : GRXWriter
 
+- (instancetype)init NS_UNAVAILABLE;
+
 /**
  * The container of the request headers of an RPC conforms to this protocol, which is a subset of
  * NSMutableDictionary's interface. It will become a NSMutableDictionary later on.
@@ -306,7 +308,7 @@ NS_ASSUME_NONNULL_END
  *
  * The property is initialized to an empty NSMutableDictionary.
  */
-@property(nullable, atomic, readonly) NSMutableDictionary *requestHeaders;
+@property(nonnull, atomic, readonly) NSMutableDictionary *requestHeaders;
 
 /**
  * This dictionary is populated with the HTTP headers received from the server. This happens before
@@ -339,9 +341,9 @@ NS_ASSUME_NONNULL_END
  * host parameter should not contain the scheme (http:// or https://), only the name or IP addr
  * and the port number, for example @"localhost:5050".
  */
-- (nullable instancetype)initWithHost:(nullable NSString *)host
-                                 path:(nullable NSString *)path
-                       requestsWriter:(nullable GRXWriter *)requestWriter;
+- (nullable instancetype)initWithHost:(nonnull NSString *)host
+                                 path:(nonnull NSString *)path
+                       requestsWriter:(nonnull GRXWriter *)requestWriter;
 
 /**
  * Finishes the request side of this call, notifies the server that the RPC should be cancelled, and
@@ -353,11 +355,11 @@ NS_ASSUME_NONNULL_END
  * The following methods are deprecated.
  */
 + (void)setCallSafety:(GRPCCallSafety)callSafety
-                 host:(nullable NSString *)host
-                 path:(nullable NSString *)path;
+                 host:(nonnull NSString *)host
+                 path:(nonnull NSString *)path;
 @property(nullable, atomic, copy, readwrite) NSString *serverName;
 @property NSTimeInterval timeout;
-- (void)setResponseDispatchQueue:(nullable dispatch_queue_t)queue;
+- (void)setResponseDispatchQueue:(nonnull dispatch_queue_t)queue;
 
 @end
 
@@ -368,11 +370,11 @@ DEPRECATED_MSG_ATTRIBUTE("Use NSDictionary or NSMutableDictionary instead.")
 @protocol GRPCRequestHeaders<NSObject>
 @property(nonatomic, readonly) NSUInteger count;
 
-- (nullable id)objectForKeyedSubscript:(nullable id)key;
-- (void)setObject:(nullable id)obj forKeyedSubscript:(nullable id)key;
+- (nullable id)objectForKeyedSubscript:(nonnull id)key;
+- (void)setObject:(nullable id)obj forKeyedSubscript:(nonnull id)key;
 
 - (void)removeAllObjects;
-- (void)removeObjectForKey:(nullable id)key;
+- (void)removeObjectForKey:(nonnull id)key;
 @end
 
 #pragma clang diagnostic push
diff --git a/src/objective-c/GRPCClient/GRPCCall.m b/src/objective-c/GRPCClient/GRPCCall.m
index dad8594a264..9b3bcd385e7 100644
--- a/src/objective-c/GRPCClient/GRPCCall.m
+++ b/src/objective-c/GRPCClient/GRPCCall.m
@@ -445,6 +445,9 @@ const char *kCFStreamVarName = "grpc_cfstream";
 }
 
 + (void)setCallSafety:(GRPCCallSafety)callSafety host:(NSString *)host path:(NSString *)path {
+  if (host.length == 0 || path.length == 0) {
+    return;
+  }
   NSString *hostAndPath = [NSString stringWithFormat:@"%@/%@", host, path];
   switch (callSafety) {
     case GRPCCallSafetyDefault:
@@ -466,10 +469,6 @@ const char *kCFStreamVarName = "grpc_cfstream";
   return [callFlags[hostAndPath] intValue];
 }
 
-- (instancetype)init {
-  return [self initWithHost:nil path:nil requestsWriter:nil];
-}
-
 // Designated initializer
 - (instancetype)initWithHost:(NSString *)host
                         path:(NSString *)path
diff --git a/src/objective-c/ProtoRPC/ProtoRPC.h b/src/objective-c/ProtoRPC/ProtoRPC.h
index 949f52d1b53..1819fa93796 100644
--- a/src/objective-c/ProtoRPC/ProtoRPC.h
+++ b/src/objective-c/ProtoRPC/ProtoRPC.h
@@ -142,11 +142,11 @@ __attribute__((deprecated("Please use GRPCProtoCall."))) @interface ProtoRPC
        * addr and the port number, for example @"localhost:5050".
        */
       -
-      (nullable instancetype)initWithHost : (nullable NSString *)host method
-    : (nullable GRPCProtoMethod *)method requestsWriter
-    : (nullable GRXWriter *)requestsWriter responseClass
-    : (nullable Class)responseClass responsesWriteable
-    : (nullable id<GRXWriteable>)responsesWriteable NS_DESIGNATED_INITIALIZER;
+      (nullable instancetype)initWithHost : (nonnull NSString *)host method
+    : (nonnull GRPCProtoMethod *)method requestsWriter
+    : (nonnull GRXWriter *)requestsWriter responseClass
+    : (nonnull Class)responseClass responsesWriteable
+    : (nonnull id<GRXWriteable>)responsesWriteable NS_DESIGNATED_INITIALIZER;
 
 - (void)start;
 @end
diff --git a/src/objective-c/examples/SwiftSample/ViewController.swift b/src/objective-c/examples/SwiftSample/ViewController.swift
index 0ba6e21f02a..4ed10266a4d 100644
--- a/src/objective-c/examples/SwiftSample/ViewController.swift
+++ b/src/objective-c/examples/SwiftSample/ViewController.swift
@@ -54,8 +54,8 @@ class ViewController: UIViewController {
       } else {
         NSLog("2. Finished with error: \(error!)")
       }
-      NSLog("2. Response headers: \(RPC.responseHeaders)")
-      NSLog("2. Response trailers: \(RPC.responseTrailers)")
+      NSLog("2. Response headers: \(String(describing: RPC.responseHeaders))")
+      NSLog("2. Response trailers: \(String(describing: RPC.responseTrailers))")
     }
 
     // TODO(jcanizales): Revert to using subscript syntax once XCode 8 is released.
@@ -68,7 +68,7 @@ class ViewController: UIViewController {
 
     let method = GRPCProtoMethod(package: "grpc.testing", service: "TestService", method: "UnaryCall")!
 
-    let requestsWriter = GRXWriter(value: request.data())
+    let requestsWriter = GRXWriter(value: request.data())!
 
     let call = GRPCCall(host: RemoteHost, path: method.httpPath, requestsWriter: requestsWriter)!
 
@@ -80,8 +80,8 @@ class ViewController: UIViewController {
       } else {
         NSLog("3. Finished with error: \(error!)")
       }
-      NSLog("3. Response headers: \(call.responseHeaders)")
-      NSLog("3. Response trailers: \(call.responseTrailers)")
+      NSLog("3. Response headers: \(String(describing: call.responseHeaders))")
+      NSLog("3. Response trailers: \(String(describing: call.responseTrailers))")
     })
   }
 }