Receiver ‘Example’ for class message is a forward declaration??

When met with this error in ObjC project while compiling, it means:

Example class is declared by @class in its invoker's class header but not directly #import.

We have 2 ways to solve this problem:

• Directly declare Example class by #import “Example.h” in the header.
• Add a method to return specific Example you want in invoker’s class header. (use this way if you use both ObjC and Swift and Example is a Swift class in a framework project.)