Hello

Your project depends on Firebase but you did not supply the Firebase frameworks to the linker.

Please read the documentation on how to use third-party frameworks (such as Firebase) within your project.

The linker errors happen while trying to link the UnityFramework binary, so you should add those frameworks in the UnityFramework tab, which is what you did ; you don't need to add them in the main app tab, unless you get linking errors when linking the main app binary.

There are two things you need to be aware of when you use precompiled libraries and frameworks :

1. Resolving dependencies at build time during the linking step :

As explained in the builder documentation, resolving dependencies is an iterative process. The first thing to do is to follow the dependency provider's instructions (readme, etc) as much as possible in order to know what frameworks are needed. When you add an extra framework, most of the time this framework also depends on other libraries or frameworks. If these libraries/frameworks are already known by the linker, your binary will link successfully, but if they aren't, which is the case here, you need to reiterate the process until all dependencies are known (resolved).

2. Resolving dependencies at runtime :

Please note, however, that a successful linking is sometimes not enough for the app to run, for example if an app tries to open a library/framework conditionally at runtime (by calling dlopen()) and that library/framework isn't here. When it's the case, the app will simply close and an error will be sent to the remote debug console (if enabled) indicating what was the missing library or framework that the app couldn't load. These frameworks need to be embedded as *embedded binaries*, and their location in the app's filesystem is dependent on where their programmer expects them to be. The expected path is typically given in the debug console error messages (most of the times, it's in the Frameworks subdirectory like the other frameworks, but it can be elsewhere, e.g. deeper in a subdirectory or in another location).

One final word :

“Info.plist added from FirebaseStorage.xcframework as well :)
I don't know if this was necessary.
Please let me know.”

Just do not do that. When you don't know what you are doing, *just don't do it*. Read the available documentations instead until you understand how things are meant to be done.

:: @Pierre-Marie Baty added on 08 Apr ’23 · 09:25

If something isn't clear and the documentation (the builder's *and* Firebase's) isn't enough for you to understand what to do, ask questions. When I notice a question that comes around frequently, it also helps me improve the documentation.

“According to the documentation the only information for Firebase SDK is the below right?:”

The paragraph you quoted is from the builder documentation. You want to use Firebase so you should first and foremost read *Firebase's documentation*. Here : https://firebase.google.com/docs/ios/setup?hl=en#integrate-without-swift-pm

“With Add binary button I can add only .dylib. In the Firebase SDK there isnt such a file.”

Do not touch that button. Your app doesn't even build yet with Firebase so you're not at the point where adding an embedded binary is needed. Do not click on buttons if you don't understand what they're meant to do.

“Where can I find the "FirebaseCore" library-framework?”

Firebase SDK download -> unzip -> File search -> "FirebaseCore" -> read the results. And you see that this framework is in the "FirebaseAnalytics" subdirectory.

This is getting out of hand...

“FirebaseAnalytics.unitypackage and FirebaseStorage.unitypackage added in the Unity project”

🫣 why on Earth did you do that ? Did you really expect it would automagically solve your linker errors just because there was "FirebaseAnalytics" and "FirebaseStorage" in these names ?

Can't you just please try to *understand* what I explain and *follow my directions* ?

" + [arm64] Linking UnityFramework...
ld: library not found for -lsblah"
This must be a joke. You've told the linker to link against a library with a *placeholder name* and are wondering why it can't find it. Do you understand *anything* on what you've been doing all along ?

By all means PLEASE STOP. You aren't going anywhere. Read and understand what I tell you. If you don't understand, read the docs and ask questions. Do so until you understand. Only do things you understand. When you don't understand what you're doing, *abstain until you do* !

The *correct way* to solve your problem is :

1. CANCEL all your random changes to your Unity project.
2. Re-create a clean Xcode project.
3. Do a "dry run" build with the builder and notice the linker errors.
4. *As told in the documentation*, do a Google search to identify the origin of the first missing symbol, i.e. which framework or library it belongs to.
5. Download and extract the third-party SDK containing that framework or library in precompiled form from its vendor or supplier (here, Google Firebase), and add it to the linker using the "Add framework" button
6. Redo from step 3 until no more errors.

If something is unclear here, ask. I will stop providing support as long as you refuse to follow these simple directions.

About this warning :

“Cocoapod installation is disabled.
If CocoaPods are not installed in your project it will not link.”

This is a technically wrong warning (it is perfectly possible to link an iOS project without using CocoaPods, even on macOS, if you use the corresponding precompiled framework binaries instead). This warning is issued to notify users that they're not going the "mainstream" way, and will have to do something on their own so that it links. It should rather be understood as : "it will not link _unless_ you do something".

“I'm I right so far?”

Yes.

“I can't figure out what to do about this:
3. Add the -ObjC linker flag in your Other Linker Settings in your target's build settings.”

These "Other Linker Settings" are a Xcode configuration field in the Xcode UI. The instruction says that you should add a linker flag here. The field where to add linker flags in the builder is called "Extra linker flags". So, you should append "-ObjC" there.

Now, your build doesn't complete successfully, and *that is expected*. Like I said, resolving missing symbols is an *iterative step*. That means you must solve them one after the other, because one error is likely to be the root cause of many successive others.

Consider your build log. What does the linker tell you ?

% build log
ld: warning: Could not find or use auto-linked framework 'FirebaseCore'
%

This line means the linker was hinted by the framework you added to also link in a dependency framework called "FirebaseCore", but it couldn't find it - which is normal, because it's in a separate directory and you haven't told it where to look for it yet. So, add the FirebaseCore framework, just like you did with the FirebaseStorage.xcframework.

Now, rebuild. You will now get other, different errors :

% build log
Undefined symbols for architecture arm64:
  "_OBJC_CLASS_$_XXXXXXXXXXXXX", referenced from:
      objc-class-ref in yyyyyyyyyy.a(zzzzzzz.mm.o)
%

A line formed this way reads : "when linking the part of your app called UnityFramework for the arm64 architecture (which is the hardware architecture of iOS devices), the linker found that an Objective-C class named "XXXXXXXXXXXXX" was called in for use, but it couldn't find its implementation anywhere".

This means there are other dependent frameworks to link in. How to identify them ? Simply follow what the documentation says, i.e. type its name (without the _OBJC_CLASS_$_" prefix) in a Google Search page, and hit the first relevant result, which should be an API reference page on that framework provider's website. You'll learn the name of the framework you need there.

Add it just like you did with the other two, and rebuild. Repeat until no more errors.

If you got to this point :

% build log
+ Creating universal framework (arm64)...
%

it means you managed to solve all the compile-time dependencies and the UnityFramework linked successfully. Congratulations.

Then you get another error :

% build log
Warning: dependency libswift_Concurrency is not among the built products. Looking for a precompiled binary...
ERROR: UnityFramework depends on unidentified library or framework: libswift_Concurrency
%

libswift_Concurrency is normally located in /usr/lib/swift in the iOS SDK. The builder should be able to find it there, but it doesn't. I checked the master build script and this reveals a bug that I'm going to fix in the next version. You can hotpatch your copy this way : open the build.cmd script file that's at the root of the install path of the builder (typically C:\Users\YourName\iOS Project Builder for Unity\build.cmd) in a text editor, and change the line that says:

% build.cmd @ line 3658 or so
		rem // is it a Swift standard library ?
		if "_!FIXABLE_NAME:~0,8!_"=="_libswift_" if exist "!SDK_PATH!\swift-5.0\!SDK_PLATFORM_NAME!\!FIXABLE_NAME!.dylib" (

			rem // if so, that's already been taken care of, as we've made sure /usr/lib/swift was in the binary load paths
%

into :

% build.cmd @ line 3658 or so
		rem // is it a Swift standard library ?
		if "_!FIXABLE_NAME:~0,8!_"=="_libswift_" if exist "!SDK_PATH!\usr\lib\swift\!FIXABLE_NAME!.tbd" (

			rem // if so, that's already been taken care of, as we've made sure /usr/lib/swift was in the binary load paths
%

Save the file and close the editor. Rebuild your app and the error should be gone.

Let me know if you have other errors past this point.

Have you followed Google's instructions on setting up your Firebase ID in your app ?

What errors or warnings do you see in the remote debug console ?

This is very unlikely to be the root cause error. Please post the full log from the remote debug console - using a paste service, such as this forum's: https://www.pmbaty.com/paste

Thank you. This is indeed the first message from Firebase Storage that appears in the logs :

“Apr 18 23:58:11.187 RemoteConsole <stderr>: 2023-04-18 23:58:10.995 AradippouMunicipality[12515:38665041] ArgumentException: Unable to initialize FirebaseStorage for bucket URL 'gs://aradippou-municipality.appspot.com'
Apr 18 23:58:11.187 RemoteConsole <stderr>: at Firebase.Storage.FirebaseStorage.GetInstanceInternal (Firebase.FirebaseApp app, System.String bucketUrl) [0x00000] in <00000000000000000000000000000000>:0
Apr 18 23:58:11.187 RemoteConsole <stderr>: at ImagePicker.Start () [0x00000] in <00000000000000000000000000000000>:0”

It's unfortunate that your app doesn't display more debug information. It could be a setup problem. Are you 100% confident that you followed all the instructions from Google here ? https://firebase.google.com/docs/storage/ios/start?hl=en#objective-c_1

I downloaded the Firebase SDK source code for iOS (the source code of the compiled Firebase frameworks) and searched for all files containing the string "for bucket URL".

It turns out that the error string above doesn't appear anywhere in the Firebase SDK. Which means it has to be generated by your app's own code. In which case you should be able to locate it and understand the logic that leads to its display. Isn't it the case ?

Please send me your Xcode project. I'll look at it.

Bottom line, user not following instructions.

I remind everybody that when building anything with Firebase on Apple platforms, Google states that you *HAVE* to specify the -ObjC linker flag.

*NO MATTER WHETHER YOUR APP APPEARS TO BUILD WITHOUT IT*

https://firebase.google.com/docs/ios/setup?hl=en#frameworks

If you get undefined symbols with this flag, this is *NORMAL*. Apple says :

“The -ObjC Linker Flag
Passing the -ObjC option to the linker causes it to load all members of static libraries that implement any Objective-C class or category. This will pickup any category method implementations. But it can make the resulting executable larger, and may pickup unnecessary objects. For this reason it is not on by default.”

https://developer.apple.com/library/archive/qa/qa1490/_index.html

Consequently, if the Firebase frameworks you need have static Objective-C classes that themselves rely on other frameworks, you have to supply these frameworks too to the builder. After that, your Firebase app will build successfully again, and most importantly, will work correctly.