Build & Archive Failed in XCode 7.3 for the imported XCode Project

Question

I'm new to the Mac platform - using Mac OS X El Capitan and installed XCode few days back. There is this iOS Application that was developed by a freelance person and now we have the source code of that. I'm trying to generate an .ipa file by building & archiving the application but it's failing regularly with below error:

No code signing identities found: No valid signing identities (ie certificate and private key pair) matching the team ID “E3NXR7ESXS” were found.

List of steps that I did to Build this Application:

1. Double-clicked on the .xcodeproj file, it opened the project on the XCode
2. Tried to Archive the Project but this icon was disabled so looked over the web and found that under the Menu Items select the Product -> Destination -> Generic iOS Device (Since no device is attached to the Mac) and then the Archive option was available.
3. First clicked on the Build and it said the Build is successful
4. Second tried to archive it and it failed with the error:

No code signing identities found: No valid signing identities (ie certificate and private key pair) matching the team ID “E3NXR7ESXS” were found.

So I checked over the web and found many answers but I'm not sure where to proceed as most of them talks about exporting/importing a developer profile OR link the developer profile with the application and since I don't have both so its a mess for me right now. Also there are answers like deleting old certificates/profiles but when I checked under the preferences there aren't any and nether any of my account is linked with the developer profile.

The only thing that I want is to generate an .ipa file so that it can be further used.

Note : My Mac is totally new, installed the latest version of XCode and after importing a project I need to Archive it to generate an .ipa file. Also there is no device attached

It's been a 2 days since I'm struggling in this. Please help me out or give me a direction from where I can see the list of steps (like if I can generate a new certificates or link my account with this application) for what to do with the imported project and generate the .ipa file from it.

Answer 1

You need to get the private key from the freelance developer. The certificate can be downloaded from the apple developer site.

If they do not have the private key or you cannot reach them, you will need to generate a new certificate and private key pair to sign your application.

If you need to generate a new certificate, here is a good guide. Note, in order to not get in this same situation when the certificate expires or if your Mac dies, make sure you backup the private key from your keychain (select it and export it, save it to a network drive somewhere safe), and the cert signing request (.csr) file. The CSR will allow you to generate a new certificate that uses the same private key. You can always generate a new CSR from the private key, so the private key, usually exported as a .p12 file, is the most critical one to back up.

Note that if you invalidate a certificate, any apps built with the certificate will stop working.