Xcode deleted my project and everything is gone. The only thing that I have is the app in my iPhone 6. So is there any way that I can retrieve the Xcode project of the app?<
Unfortunately,
There is no current way to un-archive an app. You must have the .xcodeproj file in order to make changes. The .ipa is useless in terms of editing or changing your app. And if there was a way to do so, it could and would be abused and many clones/copy's/fakes of popular apps will be published. The only accessible files are things in the Main Bundle
which only include, .pngs, .jpg, .txt etc but no source code.
Let's be clear: Xcode did not delete your project, you did, perhaps inadvertently. This does happen to most of us.
The answer is to recover from your remote Git repository or recover from Time Machine or another backup. If you do not have any backup this is your first warning that you need a backup strategy. Make this your last such warning by immediately, as in right now, creating a backup scheme, preferably two. Little is more important.
There are free remote Git repositories such as BitBucket. Setting up Time Machine is simple, just get an external disk, connect it and you will be prompted. Or use another backup scheme such as BackBlaze.
Without a backup you can recover the assets but not code from the ipa from your phone. If you are using the Asset Catalog that is not easy but can still be done.