FirebaseApp.configure(): Performing I/O on the main thread can cause hangs.

[nosferatu500]

Description

Hello!

I got this warning from Xcode today

FirebaseApp.configure(): Performing I/O on the main thread can cause hangs.

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {
        
        FirebaseApp.configure()
        
        Messaging.messaging().delegate = self

Reproducing the issue

No response

Firebase SDK Version

11.10.0

Xcode Version

16.2

Installation Method

Swift Package Manager

Firebase Product(s)

Analytics

Targeted Platforms

iOS

Relevant Log Output

If using Swift Package Manager, the project's Package.resolved

Expand Package.resolved snippet

Replace this line with the contents of your Package.resolved.

If using CocoaPods, the project's Podfile.lock

Expand Podfile.lock snippet

Replace this line with the contents of your Podfile.lock!

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.

[nosferatu500]

Stack trace lead up to the next line

// GoogleUtilities/Environment/GULAppEnvironmentUtil

+ (BOOL)isAppExtension {
#if TARGET_OS_IOS || TARGET_OS_TV || TARGET_OS_WATCH
  // Documented by <a href="https://goo.gl/RRB2Up">Apple</a>
  BOOL appExtension = [[[NSBundle mainBundle] bundlePath] hasSuffix:@".appex"];     ← here
  return appExtension;
#elif TARGET_OS_OSX
  return NO;
#endif
}

[paulb777]

Please share the stack trace

[nosferatu500]

Hi! I haven't changed anything from the last report, and for now, I see no warnings in Xcode. I will update the issue if it appears again (probably an Xcode bug).

[goppinath]

Here are some more details. Xcode is displaying a warning in FIRApp.m at line 348, indicating that performing I/O operations on the main thread can lead to slow app launches, which may affect startup performance.

However, the Firebase documentation states that the default app configuration (_FIRAPP_DEFAULT) must be initialized on the main thread. This initialization process involves synchronous file I/O to read the GoogleService-Info.plist file from disk.

I am using Xcode version 16.4. Please refer to the screenshot for additional information.