After installing Xcode 7, Xcode 6.3 shows errors about converting to Swift 2

问题

After installing Xcode 7 to play with Swift 2 in Playgrounds, I've got a weird problem:

when I open an existing Xcode 6.3 project with Xcode 6.3, it throws lots of errors about conversions to Swift 2.

This project was just cloned from the repository and hasn't been opened with Xcode 7 yet.

So my guess is that the Xcode 7 install messed up the Xcode 6.3 installed tools or something like that, but I have no idea how I could start to fix this.

I certainly don't want to open and upgrade this big project in Xcode 7 at the moment, but I do need to open it in Xcode 6.3 and Swift 1.2 to continue work on it.

回答1:

Thanks to Leo's comment, I was able to clean the caches and derived data, and these errors went away.

But then Xcode refused to build the project's included frameworks (SQLite.swift and SwiftHTTP) even after cleaning everything and rebooting.

I had to uninstall them manually, clear the "build phase" and "target" fields where they appeared, then use CocoaPods to reinstall them.

After that, my app compiled again properly in Xcode 6.3.

回答2:

1. Click on product in menubar
2. Click Clean
3. Then try reBuild project by click on play botton

it works for me

来源：https://stackoverflow.com/questions/30752203/after-installing-xcode-7-xcode-6-3-shows-errors-about-converting-to-swift-2