duplicates:

• SR-3332 @objc attribute on Linux platform leads to error

Issue Description:

When writing a cross-platform library that also exports an Objective-C interface, one has to #if entire declarations to prevent errors. Example:

class Foo {

@objc // error on Linux!

func method() { }

}

has to be written as:

class Foo {

#if os(iOS)

@objc

func method() { }

#else

func method() { }

#endif

}

We should consider ignoring @objc when the Objective-C runtime is not available. (@DougGregor)