xcodebuild -exportArchive fails for tvOS apps

Question

If I tried to export an .ipa from an .xcarchive using the command line using xcodebuild as such:

xcodebuild archive -scheme "Cross" -archivePath "build/Cross.xcarchive"
xcodebuild -exportArchive -archivePath "build/Cross.xcarchive" -exportPath "build/Cross-tvOS.ipa"

it fails with the error "the platform is unknown: appletvos":

+ xcodebuild -exportArchive -archivePath build/Cross.xcarchive -exportFormat app -exportPath build/Cross-tvOS.ipa
--- xcodebuild: WARNING: -exportArchive without -exportOptionsPlist is deprecated
2015-11-30 22:13:44.403 xcodebuild[42874:30912505] [MT] DVTAssertions: Warning in /Library/Caches/com.apple.xbs/Sources/IDEFrameworks/IDEFrameworks-9081/IDEFoundation/Execution/Archiving/IDEArchivedApplication.m:148
Details:  Asked if we support packaging as a given format, but the platform is unknown: appletvos
Object:   <IDEArchivedApplication: 0x7f89bea3e990>
Method:   -supportsPackagingAsFormat:
Thread:   <NSThread: 0x7f89bbc320d0>{number = 1, name = main}
Please file a bug at http://bugreport.apple.com with this warning message and any useful information you can provide.
error: archive at path '/Users/pol/Downloads/Cross/tvOS/build/Cross.xcarchive' cannot be exported as APP
** EXPORT FAILED **

I can successfully export the .ipa using the Xcode Organizer. This was observed on Xcode version 7.1.1.

Answer 1

It turns out the error message is misleading. This failure happens if you don't specify the -exportOptionsPlist argument.

Even passing a fake empty .plist file like this fixes the issue:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict/>
</plist>