How to re-sign an iOS app with another developer account

re-sign-ios-app.md

WARNING These steps are probably out dated and will not work.

To re-sign an iOS app with another developer account, ensure that the following are in place first.

1. Distribution certificate of the other developer account
2. A provisioning profile from the other developer account

Note that the Apple requires bundle IDs to be globally unique, even across accounts. So a bundle ID i.e. CFBundleIdentifier from one account can't be used in a different account, even though the team id/prefix would be different.

Ensure that the new distribution certificate is in your keychain and the new provisioning profile on your disk.

1. Unzip the .ipa. This will usually unzip to Payload/<app-name>.app/

2. Export entitlements.plist from the app using the codesign utility

    codesign -d --entitlements :entitlements.plist /path/to/<app-name>.app/
   

3. Open entitlements.plist in your favourite editor, and modify the bundle id and prefix to that of the new dev account and app. Don't forget to update the keychain access groups.

4. Open Info.plist in your favourite editor and modify the bundle identifier (CFBundleIdentifier). It can be found at /path/to/<app-name.app>/Info.plist.

5. Replace the embedded provisioning profile.

    cp /path/to/new-profile.mobileprovision /path/to/<app-name>.app/embedded.mobileprovision
   

6. Install the new signature.

    codesign -f -s "Distribution Certificate Name" -i com.example.new_bundle_id --entitlements entitlements.plist -vv /path/to/<app-name>.app/
   

7. Package the application

    xcrun -sdk iphoneos PackageApplication -s "Distribution Certificate Name" -o /path/to/new.ipa /path/to/<app-name>.app
   

8. Distribute /path/to/new.ipa to your testers.

Can I resign a distribution signed IPA with a development certificate? My app crashe constantly at launch time. I don't get it...

Step 7 can be skipped (at least since PackageApplication is deprecated), just zip up your Payload folder:
zip -r /path/to/new.ipa /path/to/Payload

I successfully re signed an IPA file following the steps above. The IPA file can be downloaded after being placed on my server. But it cannot be opened after the download is completed

I successfully re signed an IPA file following the steps above. The IPA file can be downloaded after being placed on my server. But it cannot be opened after the download is completed

As for the most of iOS errors, it's almost impossible to figure out the actual reason from its message. You should observe device logs at the moment when installation is finished or when you first try to run the app.