Go to Xcode Project > Build Settings and type "header name", you will get the below option:
![enter image description here](https://i.stack.imgur.com/nEQhc.png)
Make sure that there must exist a file with a name: $(SWIFT_MODULE_NAME)-Swift.h
Then type, "bridging header" under Build Settings and make sure that the path of "bridging-header.h" file exist correctly.
![enter image description here](https://i.stack.imgur.com/Ksk6x.png)
Edited:
1) Make sure that your "Project Name" doesn't contains spaces
2) Well "XXX-Swift.h" file is generated at the following path, so you need to add that path to unit test - Go to build settings, type "Header Search Paths" and add the following line
"$(TARGET_TEMP_DIR)/../$(PROJECT_NAME).build/DerivedSources"
For more, you can refer this link : iOS - 'MyProject-Swift.h' file not found when running Unit Tests for Swift
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