Fix use of handle in AppCheck block (#1306)

* Fix use of handle in AppCheck block

* Update app_check_ios.mm

Author: a-maurice

app_check/src/ios/app_check_ios.mm

@@ -176,11 +176,9 @@ - (void)appCheckTokenDidChangeNotification:(NSNotification*)notification {
 }
 
 Future<AppCheckToken> AppCheckInternal::GetAppCheckToken(bool force_refresh) {
-  SafeFutureHandle<AppCheckToken> handle =
+  __block SafeFutureHandle<AppCheckToken> handle =
       future()->SafeAlloc<AppCheckToken>(kAppCheckFnGetAppCheckToken);
 
-  // __block allows handle to be referenced inside the objective C completion.
-  __block SafeFutureHandle<AppCheckToken>* handle_in_block = &handle;
   [impl()
       tokenForcingRefresh:force_refresh
                completion:^(FIRAppCheckToken* _Nullable token, NSError* _Nullable error) {
@@ -190,18 +188,18 @@ - (void)appCheckTokenDidChangeNotification:(NSNotification*)notification {
                    int error_code = firebase::app_check::internal::AppCheckErrorFromNSError(error);
                    std::string error_message = util::NSStringToString(error.localizedDescription);
 
-                   future()->CompleteWithResult(*handle_in_block, error_code, error_message.c_str(),
+                   future()->CompleteWithResult(handle, error_code, error_message.c_str(),
                                                 cpp_token);
                    return;
                  }
                  if (token == nil) {
                    NSLog(@"App Check token is nil.");
-                   future()->CompleteWithResult(*handle_in_block, kAppCheckErrorUnknown,
+                   future()->CompleteWithResult(handle, kAppCheckErrorUnknown,
                                                 "AppCheck GetToken returned an empty token.",
                                                 cpp_token);
                    return;
                  }
-                 future()->CompleteWithResult(*handle_in_block, kAppCheckErrorNone, cpp_token);
+                 future()->CompleteWithResult(handle, kAppCheckErrorNone, cpp_token);
                }];
   return MakeFuture(future(), handle);
 }