If you do not want to use testflight, here is another solution:
In the xcode project go to Product > Archive
Click Distribute in the xcode organizer window, which appears when the operation is complete.
Click Save for Enterprise or Ad Hoc Deployment and select the next
Select your custom profile profile (created at the Member Center on developer.apple.com. Make sure all 20 uuids are included.
Click Export
Save it. Be sure to click on the Save for enterprise distribution check box and fill in the required information. The application URL will be a URL starting with http: // or https: //, which will go to your files (see next step)
This will save the two files yourFilename.ipa and yourFileName.plist . Copy these files to your web server.
Now for the magic. You need to make a link somewhere with the itms-services://?action=download-manifest&url=http://yourwebserver.com/path/to/yourFileName.plist URL itms-services://?action=download-manifest&url=http://yourwebserver.com/path/to/yourFileName.plist
Assuming all your links are working and your configuration profiles are correct, the application should begin installation on any registered device that clicks on this link.
If you do not want to load air, you can distribute this .ipa file, which was generated in step 6, to your 20 people (their devices must be registered in the training profile yet). They can open this file in iTunes and then synchronize the application with their devices.
Installing the application on the air or synchronizing with iTunes will not destroy the contents of any devices.
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