If you submit your app to iTunes Connect and shortly afterwards you get back an email from the iTunes store stating that your app has the problem of an invalid signature, here is a possible solution for this problem.
- Select the target you want to submit and go to the „Build Settings“ tab.
- Locate the category „Code Signing“.
- In this category you set the „Code Signing Identity“ for the Release configuration to „iPhone Distribution“.
The screenshot below might help you: