Swift & Objective-C project - generated -Swift.h error - Cannot find interface declaration for UIViewController

Question

I've got a project using the Swift generated Bridging Header and have the project set up correctly (no spaces in Names, Uses Modules, pre-declaring Swift classes in my .mm file, Deleting derived data, doing a clean rebuild etc...). The Bridging Header is being generated fine, but the automatically generated -Swift.h has errors in it. What's even worse, those errors are on the generated (in project creation - Swift) versions of AppDelegate and ViewController which would normally compile fine. The errors in the -Swift.h are:

• @interface AppDelegate : UIResponder <UIApplicationDelegate>
  >> Cannot find interface declaration for 'UIResponder', superclass of 'AppDelegate'
  >> Cannot find protocol declaration for 'UIApplicationDelegate'
• @interface ViewController : UIViewController
  >> Cannot find interface declaration for 'UIViewController', superclass of 'ViewController'

I've searched Stack Overflow and the net and can't find any answer that addresses this particular issue. Has anyone else had this? Or, is there a way I can mark my AppDelegate and ViewController classes so Xcode doesn't try and create Objective-C stubs for those Swift classes as I don't actually need them?

Answer 1

Just add

#import <UIKit/UIKit.h>

before

#import <YourProject-Swift.h>

in .mm file. for me it helps.

Answer 2

I had same problem and discovered that..

-Swift.h only work best with Objective-C, not Objective-C++ (.mm)

So I use the Objective-C class to connect with the Swift class. Also You can always load your Objective-C++ class in your Objective-C class.

Answer 3

Try to import UIKit/UIKit.h into bridging header file.

Answer 4

Swift doesn’t play very well with Objective-C++. Since I need to interface with C++, I tend to write an Objective-C++ class MyClass_CPP containing just the interface with C++, then an Objective-C subclass MyClass that can play nicely with Swift.

Answer 5

Here's the latest working answer so far (2023).

In my case, this has happened before, when I was working on a chat feature in my Objective-C project.

And now, I want to subclass AVPlayerViewController in Swift, and use that Swift subclass in my Objective-C file.

One way to fix this is to have an Objective-C subclass to subclass the module class of any iOS framework (e.g. AVKit). Then use that Objective-C subclass as the superclass of your Swift subclass.