Swift project does not directly recognize Objective C files added to the project.
There are a couple of steps after you drag and drop the framework to the project.
First, you have to create a Bridging-Header.
Create a new Header file. Usually its named "project_name-Bridging-Header.h".
In Build Settings, search for "Objective-C Bridging Header" and set the value to Bridging header file name. You will have to provide the path from your project directory.
Now add import <iSoma/iSoma.h>
in the Bridging Header. You should be then able to access the Objective file in Swift file.