“Your binary is not optimized for iPhone 5” (ITMS-90096) when submitting

Update August 2016

When using Xcode 7+ and targeting iOS 8+ it is recommended to remove the .xib file and create a new LaunchScreen.storyboard by using the given template:

And than setting it in the Project File under App Icons and Launch Images:

Original October 2015 Answer

So like @Aditya Deshmane I also use .xib file as my “Launch Image”.

Adding both Default-568.png and Default-568@2x.png to my root directory didn’t solve my issue.

I had to add the UILaunchImages key to my Info.plist:

<key>UILaunchImages</key>
<array>
    <dict>
        <key>UILaunchImageName</key>
        <string>Default-568</string>
        <key>UILaunchImageSize</key>
        <string>{320, 568}</string>
    </dict>
</array>

As described here: iOS Key UILaunchImages