turing complete with a stack of 0xdeadbeef
I recently discovered that unit tests and UI tests for a macOS Xcode project will fail with obscure error messages if the hardened runtime is enabled. It took me awhile to realize what the actual source of the problem was, because the error messages led me in the wrong direction. Hopefully this will save you some time.
OCMock is a powerful mock object unit testing library for Objective-C. Even if you are using Swift, as long as your classes inherit from NSObject, you can use some of its features. But what if you are writing pure Swift code which does not have access to the dynamic Objective-C runtime? Or, what if you don’t want your Swift code to be hampered by NSObject subclasses and @objc annotations? Perhaps, you merely want to avoid dependencies and use ‘plain old’ XCTest with Objective-C. It’s relatively easy and lightweight to achieve the same effect in some testing scenarios without using OCMock.
Core Data is probably loved as much as it is shunned by iOS developers. It is a framework of great power that often comes with great frustration. But it remains a popular tool among developers despite its pitfalls — likely because Apple continues to invest in it and encourages its adoption, as well as the availability of the many open-source libraries that make Core Data easier to use. Consider unit testing, and Core Data gets a bit more cumbersome. Luckily, there are established techniques to facilitate testing your models. Add Swift to this equation, and the learning curve gets slightly steeper.