The best answer I found was on the Apple developer site. Imagine this? You can follow the link below, but basically this:
1) click on the target in xcode, on the right in βIdentify and printβ under the name, change the name and press the ENTER button on the keyboard.
2) a window appears confirming the change and what it will change. After confirmation, he will make the changes.
https://developer.apple.com/library/ios/qa/qa1625/_index.html
OR ANOTHER WAY AND EVEN EASY:
left-click on the project name and rename it. Once you rename it, you ask if you want to rename:


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