Export .ipa file from Xcode project without ever opening Xcode - ios

Question

We have an API that users can call to create Cordova apps/projects, upload their www directory, and then start compilation and download the executable binary file. This binary file will then go into a private app store.
I'm having trouble with the compile step for iOS. The Cordova build step is no problem, but it doesn't output a binary file, like it does for Android. After reading everything I found on Stackoverflow and elsewhere, the plan was this:
xcodebuild clean -configuration Release -alltargets
xcodebuild -scheme MyApp archive -archivePath build/MyApp
xcodebuild -exportArchive -exportFormat ipa -archivePath "build/MyApp.xcarchive" -exportPath "MyApp.ipa" -exportProvisioningProfile "My Prov Profile"
Given that the signing identity and everything is set up correctly, it almost works. The first command executes fine. The second command just hangs.
However, if I open the project in Xcode, and then execute the commands, it compiles and exports, and I'm left with an .ipa file, which is what I wanted. It seems that Xcode sets up a workspace and some scheme-related things when the project is first opened.
Is there any way I can get xcodebuild (or xcrun, or anything, for that matter) to create this workspace file for me?
Or is there another way to approach this?
Right now, I have a solution where I actually open the Xcode project, wait 15 seconds, and then proceed. But I can think of a thousand ways that will fail at some point, so I would like to change it to something a little more elegant.
I currently have Xcode 6.3 installed, if that is relevant.
Update: Opal's answer below set me on the right path (I think). What I ended up doing, was exporting a shared scheme as per Opal's link, and using that as a template for future apps. The solutions was something like this:
# Copy shared scheme file into directory
mkdir /path/to/project/dir/MyApp.xcodeproj/xcshareddata
mkdir /path/to/project/dir/MyApp.xcodeproj/xcshareddata/xcschemes
cp data/MyScheme.xcscheme /path/to/project/dir/MyApp.xcodeproj/xcshareddata/xcschemes/.
# Use sed to replace app name in scheme file
sed -i '' "s/%app_name%/MyApp/g" MyApp.xcodeproj/xcshareddata/xcschemes/MyScheme.xcscheme
# CD into directory
cd /path/to/project/dir
# Move files from Cordova to our build directory
cp -r CordovaLib/build/* build/.
# Build and export
xcodebuild clean -configuration Release -alltargets
xcodebuild -scheme MyScheme archive -archivePath build/MyApp
xcodebuild -exportArchive -exportFormat ipa -archivePath "build/MyApp.xcarchive" -exportPath "MyApp.ipa" -exportProvisioningProfile "MyProvProfile"

Answer 1

It seems that the application you try to build has no shared schemes. Schemes if not shared, are created when project is loaded to xcode. To create shared schemes see this site.

Answer 2

These are the steps I used to automate ipa generation without opening xcode in my cordova environment. (xcode version: 6.0.1 cordova version: 3.6.0)
Change in cordova/build.xcconfig: CODE_SIGN_IDENTITY=iPhone Distribution (change "Developer" to "Distribution". )
run cordova build ios --device in cordova workspace that generates .app file
Sign using : xcrun -sdk iphoneos PackageApplication -v ${WORKSPACE}/platforms/ios/build/device/${application.name}.app -o ${WORKSPACE}/platforms/ios/build/${application.name}.ipa --embed ${ios.distribution.provisionfile}.mobileprovision --sign ${code.signing.identity}