Xcode 8 Objective-C category warning

Question

I\'m using Xcode 8 and Swift 3.0. What does this error message mean?

ld: warning: Some object files have incompatible Objective-C category definition

Answer 1

In my case, the reason was having computed type property in an extension:

extension NSParagraphStyle {
    class var defaultStyle: NSParagraphStyle {
        return ...
    }
}

Not sure what the exact reason behind this is, but to get rid of the warning I had to convert the computed type property (class var) to a type method (class func):

extension NSParagraphStyle {
    class func defaultStyle() -> NSParagraphStyle {
        return ...
    }
}