Build & Archive Failed in XCode 7.3 for the imported XCode Project
<p>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 &amp; archiving the application but it's failing regularly with below error:</p>

<blockquote>
  <p>No code signing identities found: No valid signing identities (i.e. certificate and private key pair) matching the team ID “E3NXR7ESXS” were found. </p>
</blockquote>

<p>List of steps that I did to Build this Application:</p>

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

<blockquote>
  <p>No code signing identities found: No valid signing identities (i.e.
  certificate and private key pair) matching the team ID “E3NXR7ESXS”
  were found.</p>
</blockquote>

<p>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.</p>

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

<p><strong>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</strong></p>

<p>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 <code>(like if I can generate a new certificates or link my account with this application)</code> for what to do with the imported project and generate the .ipa file from it.</p>