You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: GTMSessionFetcher.m
    path of file: ./repos/SwiftUIAuthenticationCompleted/Pods/GTMSessionFetcher/Source
    
    the code of the file until where you have to start completion: /* Copyright 2014 Google Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#if !defined(__has_feature) || !__has_feature(objc_arc)
#error "This file requires ARC support."
#endif

#import "GTMSessionFetcher.h"
#if TARGET_OS_OSX && GTMSESSION_RECONNECT_BACKGROUND_SESSIONS_ON_LAUNCH
// To reconnect background sessions on Mac outside +load requires importing and linking
// AppKit to access the NSApplicationDidFinishLaunching symbol.
#import <AppKit/AppKit.h>
#endif

#import <sys/utsname.h>

#ifndef STRIP_GTM_FETCH_LOGGI
    
function concurrently with any other function that uses
  // the same trust management object, or to re-enter this function for the same trust
  // management object."
  //
  // SecTrustEvaluateAsync both does sync execution of Evaluate and calls back on the
  // queue passed to it, according to at sources in
  // http://www.opensource.apple.com/source/libsecurity_keychain/libsecurity_keychain-55050.9/lib/SecTrust.cpp
  // It would require a global serial queue to ensure the evaluate happens only on a
  // single thread at a time, so we'll stick with using SecTrustEvaluate on a background
  // thread.
  dispatch_queue_t evaluateBackgroundQueue =
    dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
  dispatch_async(evaluateBackgroundQueue, ^{
    // It looks like the implementation of SecTrustEvaluate() on Mac grabs a global lock,
    // so it may be redundant for us to also lock, but it's easy to synchronize here
    // anyway.
    BOOL shouldAllow;
#if GTM_SDK_REQUIRES_SECTRUSTEVALUATEWITHERROR
    CFErrorRef errorRef = NULL;
    @synchronized ([GTMSessionFetcher class]) {
      GTMSessionMonitorSynchronized([GTMSessionFetcher class]);

      // SecTrustEvaluateWithError handles both the "proceed" and "unspecified" cases,
      // so it is not necessary to check the trust result the evaluation returns true.
      shouldAllow = SecTrustEvaluateWithError(serverTrust, &errorRef);
    }

    if (errorRef) {
      GTMSESSION_LOG_DEBUG(@"Error %d evaluating trust for %@",
                           (int)CFErrorGetCode(errorRef), request);
      CFRelease(errorRef);
    }
#else
    SecTrustResultType trustEval = kSecTrustResultInvalid;
    OSStatus trustError;
    @synchronized([GTMSessionFetcher class]) {
      GTMSessionMonitorSynchronized([GTMSessionFetcher class]);

      trustError = SecTrustEvaluate(serverTrust, &trustEval);
    }
    if (trustError != errSecSuccess) {
      GTMSESSION_LOG_DEBUG(@"Error %d evaluating trust for %@",
                           (int)trustError, request);
      shouldAllow = NO;
    } else {
      // Having a trust level "unspecified" by the user is the usual result, described at
      //   https://developer.apple.com/library/mac/qa/qa1360
      if (trustEval == kSecTrustResultUnspecified
          || trustEval == kSecTrustResultProceed) {
        shouldAllow = YES;
      } else {
        shouldAllow = NO;
        GTMSESSION_LOG_DEBUG(@"Challenge SecTrustResultType %u for %@, properties: %@",
                             trustEval, request.URL.host,
                             CFBridgingRelease(SecTrustCopyProperties(serverTrust)));
      }
    }
#end