"Dyld Error Message: Library not loaded" crash with 2nd level dependency

[lassana]

Hi there,
I'm currently working on iOS bindings for cobrowse.io library and I have found quite interesting behavior that I'd like to share with you.

The CobrowseIO is actually an ObjC library but it depends on two Swift libs: SocketIO and Starscream. So, I have created three separate bindings projects, and the dependency hierarchy looks like:

MyiOSApplication
+
+-->CobrowseIO.iOS
|   +
+---+-->SocketIO.iOS
|       +
+-------+-->Starscream.iOS

The app worked fine on iPhone with iOS 12.2 and I was surprised when my app crashed on simulator with the following message:

Dyld Error Message:
  Library not loaded: @rpath/SocketIO.framework/SocketIO
  Referenced from: /Users/USER/Library/Developer/CoreSimulator/Devices/CBD647EE-9558-45C3-9715-E7511F5662C7/data/Containers/Bundle/Application/FE14C4FA-E404-43E8-984B-5289FC7B24B8/MyiOSApplication.app/Frameworks/CobrowseIO.framework/CobrowseIO
  Reason: image not found

Build log:

Target "_SwiftFrameworksMac" in file "/Users/user/.nuget/packages/xamarin.swift/1.0.2/build/xamarinios/Xamarin.Swift.targets":
  Using "CheckSwiftVersionsTask" task from assembly "/Users/user/.nuget/packages/xamarin.swift/1.0.2/build/xamarinios/../../SwiftSupport.dll".
  Task "CheckSwiftVersionsTask"
    Looking for Swift version on: bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/CobrowseIO.framework/CobrowseIO
    Expected Swift header on: bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/CobrowseIO.framework/Headers/CobrowseIO-Swift.h
    bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/CobrowseIO.framework/Headers/CobrowseIO-Swift.h do not exist.
    Installed: 5.0
  Done executing task "CheckSwiftVersionsTask".
  Task "ScanSwiftTask" skipped, due to false condition; ($(_ShouldIncludeSwiftDylibs)) was evaluated as (False).
  Task "IncludeSwiftTask" skipped, due to false condition; ($(_ShouldIncludeSwiftDylibs)) was evaluated as (False).

As you can see, Xamarin.Swift didn't check if SocketIO.iOS and Starscream.iOS were actually Swift bindings.

The workaround is pretty simple: I just added the following lines to the LinkerPleaseInclude file:

public void Include(Starscream.FoundationStream _)
{
    _ = new Starscream.FoundationStream();
}

public void Include(SocketIO.SocketManager _)
{
    _ = new SocketIO.SocketManager(new NSUrl("https://example.com"), null);
}

The app now no longer crashes and the build log contains this:

Target "_SwiftFrameworksMac" in file "/Users/user/.nuget/packages/xamarin.swift/1.0.2/build/xamarinios/Xamarin.Swift.targets":
  Using "CheckSwiftVersionsTask" task from assembly "/Users/user/.nuget/packages/xamarin.swift/1.0.2/build/xamarinios/../../SwiftSupport.dll".
  Task "CheckSwiftVersionsTask"
    Looking for Swift version on: bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/CobrowseIO.framework/CobrowseIO
    Looking for Swift version on: bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/Starscream.framework/Starscream
    Looking for Swift version on: bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/SocketIO.framework/SocketIO
    Expected Swift header on: bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/Starscream.framework/Headers/Starscream-Swift.h
    bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/Starscream.framework/Headers/Starscream-Swift.h exists.
    Expected Swift header on: bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/CobrowseIO.framework/Headers/CobrowseIO-Swift.h
    Expected Swift header on: bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/SocketIO.framework/Headers/SocketIO-Swift.h
    bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/CobrowseIO.framework/Headers/CobrowseIO-Swift.h do not exist.
    bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/SocketIO.framework/Headers/SocketIO-Swift.h exists.
    Including Swift dylibs because you are targeting an OS version that doesnt include it.
    Installed: 5.0
    SocketIO Framework: 5.0
    Starscream Framework: 5.0
  Done executing task "CheckSwiftVersionsTask".
  Using "ScanSwiftTask" task from assembly "/Users/user/.nuget/packages/xamarin.swift/1.0.2/build/xamarinios/../../SwiftSupport.dll".
  Task "ScanSwiftTask"
    Frameworks: bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/CobrowseIO.framework/CobrowseIO, bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/SocketIO.framework/SocketIO, bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/Starscream.framework/Starscream
    Looking for Swift Dependency on: bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/CobrowseIO.framework/CobrowseIO
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/otool -l 'bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/CobrowseIO.framework/CobrowseIO'
    Looking for Swift Dependency on: bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/SocketIO.framework/SocketIO
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/otool -l 'bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/SocketIO.framework/SocketIO'
    Looking for Swift Dependency on: bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/Starscream.framework/Starscream
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/otool -l 'bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/Starscream.framework/Starscream'
    Swift Dependency Found: libswiftCore.dylib
    Swift Dependency Found: libswiftCoreFoundation.dylib
    Swift Dependency Found: libswiftCoreGraphics.dylib
    Swift Dependency Found: libswiftCoreImage.dylib
    Swift Dependency Found: libswiftDarwin.dylib
    Swift Dependency Found: libswiftDispatch.dylib
    Swift Dependency Found: libswiftFoundation.dylib
    Swift Dependency Found: libswiftMetal.dylib
    Swift Dependency Found: libswiftObjectiveC.dylib
    Swift Dependency Found: libswiftQuartzCore.dylib
    Swift Dependency Found: libswiftUIKit.dylib
    Looking for Swift Dependency on: libswiftCore.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/otool -l '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftCore.dylib'
    Looking for Swift Dependency on: libswiftCoreGraphics.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/otool -l '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftCoreGraphics.dylib'
    Looking for Swift Dependency on: libswiftObjectiveC.dylib
    Looking for Swift Dependency on: libswiftDarwin.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/otool -l '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftDarwin.dylib'
    Looking for Swift Dependency on: libswiftCoreImage.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/otool -l '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftCoreImage.dylib'
    Looking for Swift Dependency on: libswiftDispatch.dylib
    Looking for Swift Dependency on: libswiftMetal.dylib
    Looking for Swift Dependency on: libswiftUIKit.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/otool -l '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftUIKit.dylib'
    Looking for Swift Dependency on: libswiftCoreFoundation.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/otool -l '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftCoreFoundation.dylib'
    Looking for Swift Dependency on: libswiftQuartzCore.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/otool -l '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftQuartzCore.dylib'
    Looking for Swift Dependency on: libswiftFoundation.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/otool -l '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftMetal.dylib'
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/otool -l '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftObjectiveC.dylib'
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/otool -l '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftFoundation.dylib'
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/otool -l '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftDispatch.dylib'
    Swift Dependency Found: libswiftos.dylib
    Looking for Swift Dependency on: libswiftos.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/otool -l '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftos.dylib'
  Done executing task "ScanSwiftTask".
  Using "IncludeSwiftTask" task from assembly "/Users/user/.nuget/packages/xamarin.swift/1.0.2/build/xamarinios/../../SwiftSupport.dll".
  Task "IncludeSwiftTask"
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftCore.dylib' -archs
    Copying: libswiftCore.dylib, libswiftCoreFoundation.dylib, libswiftCoreGraphics.dylib, libswiftCoreImage.dylib, libswiftDarwin.dylib, libswiftDispatch.dylib, libswiftFoundation.dylib, libswiftMetal.dylib, libswiftObjectiveC.dylib, libswiftQuartzCore.dylib, libswiftUIKit.dylib, libswiftos.dylib
    Swift Arcs Needed: i386, x86_64
    Swift Arcs Available: i386, x86_64
    Copying: libswiftCore.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftCore.dylib'  -create -output 'bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/libswiftCore.dylib'
    Copying: libswiftCoreFoundation.dylib
    Copying: libswiftCoreImage.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftCoreFoundation.dylib'  -create -output 'bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/libswiftCoreFoundation.dylib'
    Copying: libswiftCoreGraphics.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftCoreGraphics.dylib'  -create -output 'bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/libswiftCoreGraphics.dylib'
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftCoreImage.dylib'  -create -output 'bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/libswiftCoreImage.dylib'
    Copying: libswiftDarwin.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftDarwin.dylib'  -create -output 'bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/libswiftDarwin.dylib'
    Copying: libswiftDispatch.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftDispatch.dylib'  -create -output 'bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/libswiftDispatch.dylib'
    Copying: libswiftFoundation.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftFoundation.dylib'  -create -output 'bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/libswiftFoundation.dylib'
    Copying: libswiftMetal.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftMetal.dylib'  -create -output 'bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/libswiftMetal.dylib'
    Copying: libswiftQuartzCore.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftQuartzCore.dylib'  -create -output 'bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/libswiftQuartzCore.dylib'
    Copying: libswiftUIKit.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftUIKit.dylib'  -create -output 'bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/libswiftUIKit.dylib'
    Copying: libswiftos.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftos.dylib'  -create -output 'bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/libswiftos.dylib'
    Copying: libswiftObjectiveC.dylib
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/lipo '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator/libswiftObjectiveC.dylib'  -create -output 'bin/iPhoneSimulator/Debug/MyiOSApplication.app/Frameworks/libswiftObjectiveC.dylib'
  Done executing task "IncludeSwiftTask".
Done building target "_SwiftFrameworksMac" in project "MyiOSApplication.csproj".

Apparently, _Frameworks MSBuild item does not include frameworks that aren't used in the app's code directly.

[Flash3001]

Thanks for sharing that @lassana . That is very interesting. I had no idea this was an issue.

On one hand this is a feature on C# world as the app won't include things it doesn't need, but as this is a reference to the native world (either Swift or Objective-C) it can't rely only on C# references. I wonder if the behaviour is different for Swift and Objective-C bindings.

I know that when doing a binding you can include a list of dependencies for frames on the link with.cs file. Something like Frameworks = "SocketIO" have you tried that to see if it changes anything?

[lassana]

@Flash3001 I ended up with a LinkerPleaseInclude file added to the ObjC binding project, which references C# code from Swift binding projects. Something like this.