Building Unreal Source from Xcode

Development Getting Started & Setup
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Did something change in the source that would prevent this? I had to rebuild my Mac. I was DEFINITELY able to do this before, but now it’s throwing literally hundreds of errors like I’m missing a pre-req, but I’ve scanned all the documentation I can find and can’t seem to find what I’m missing.

Error example:

/Users/me/UnrealEngine/UnrealEngine/Engine/Source/Runtime/Core/Public/HAL/PerModuleInline.inl:10:1: implicit conversion loses integer precision: 'size_t' (aka 'unsigned long') to 'uint32' (aka 'unsigned int') [-Werror,-Wshorten-64-to-32]

   39 |         void* FMemory_Malloc ( size_t Size, size_t Alignment                 ) { return FMemory::Malloc( Size ? Size : 1, Alignment ); } \

      |                                                                                         ~~~~~~~                           ^~~~~~~~~

In file included from /Users/me/UnrealEngine/UnrealEngine/Engine/Intermediate/Build/Mac/arm64/ShaderCompileWorker/Development/SourceControl/Module.SourceControl.cpp:2:

In file included from /Users/me/UnrealEngine/UnrealEngine/Engine/Intermediate/Build/Mac/arm64/ShaderCompileWorker/Development/SourceControl/PerModuleInline.gen.cpp:5:

/Users/me/UnrealEngine/UnrealEngine/Engine/Source/Runtime/Core/Public/Modules/Boilerplate/ModuleBoilerplate.h:39:116: expanded from macro 'UE_DEFINE_FMEMORY_WRAPPERS'

   10 | UE_DEFINE_FMEMORY_WRAPPERS

      | ^~~~~~~~~~~~~~~~~~~~~~~~~~
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try to downgrade your Xcode to 16.2 :upside_down_face:

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That sure looks like it did the trick. Way to be backwards compatible Apple! :laughing:

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Just tried it and it worked! Thanks a lot!

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please note that, the engine team from epic has committed Xcode16.3 required compilation fixes to dev_UE5.5 branch, that might solve your issue.

https://github.com/EpicGames/UnrealEngine/commit/d93b445637ff147e411d8db59f4b9a26c469cb53#diff-c587f722375cc2f6b87ea7e6274c3af886f82b7f679bf138e7aea2b8faa77b41

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Clone the Unreal Engine repository from GitHub before building Unreal Engine source from Xcode. Using the Xcode IDE, open the .uproject file, configure settings, and build.

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If you want to keep using 16.3, you can download the patch for the changelist Yoda_Yu posted here. Then, apply it with git apply (path/to/patch), and rebuild project files. Note that you’ll want to undo this before you update to a newer Unreal version to avoid conflicts.

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The someone may encounter another issue if they are on Intel family Cpu:

Screenshot 2025-05-02 at 10.27.41
Screenshot 2025-05-02 at 10.27.412468×414 181 KB

this audio plugin i think seldom people know it, if you don’t need it , just remove it ( simply by renaming Harmonix.uplugin to Harmonix.2uplugin ), and then launch compiler again:

./Engine/Build/BatchFiles/Mac/Build.sh UnrealEditor Mac Development
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(post deleted by author)

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I tried this, here is the result:

/Documents/Unreal/UnrealEngine/Engine/Source/Programs/UnrealBuildTool/ToolChain/AppleToolChain.cs(479,65): error CS1061: ‘AppleToolChain.AppleToolChainInfo’ does not contain a definition for ‘AppleClangVersion’ and no accessible extension method ‘AppleClangVersion’ accepting a first argument of type ‘AppleToolChain.AppleToolChainInfo’ could be found (are you missing a using directive or an assembly reference?) [/Documents/Unreal/UnrealEngine/Engine/Source/Programs/UnrealBuildTool/UnrealBuildTool.csproj]

Any ideas?

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That’s strange; on my machine, AppleToolChain.cs::479 doesn’t reference AppleClangVersion at all. Are you building from 5.5.4? That’s what the patch applies to.