问题:

After upgrading Xcode to 7.3, I just found that some modules are stricken out while importing, like in this screenshot:

But after adding the module (so just pressing enter) everything is fine. What does that mean? The module here is written in Swift and works fine.

回答1:

This is a bug. We have fixed it in 218010af, which should be included in the Swift 2.2.1 release and is included in the 2016-04-12-a developer snapshot.

回答2:

The strikethrough occurs if you try to import a module that has already been imported by your file or module:

In this case, I have already imported Foundation (which implicitly imports CoreFoundation), so Xcode is telling you that there is no need to import either module again.

回答3:

I changed the order of the imports

import Foundation
import UIKit
import LayerKit
import Atlas  < red line


import Foundation
import UIKit
import Atlas
import LayerKit

Some notes that may be causing it:

LayerKit importing Atlas even though LayerKit is the lower level API Atlas is the UI layer
Both were Cocoapod imports
Error appeared when I created an 2nd Schema for App Store/Enteprise releases and cleaned one and switch to the other.
Deleting Derived Data didnt clear it.
So tried rearranging them and red line disappeared