Perhaps most smaller apps, yes. And some big ones too. But a very significant percentage of the commercial software industry writes apps for OSX in C++, including Autodesk, Adobe, many major games written using engines like Unreal and Unity (which also support other languages), etc.
That's not a knock against anyone who does or doesn't write apps in a particular language; but folks should know what the reality is, and Objective C or Swift are by no means the only or even necessarily the most profitable ways to writes apps for OSX, though those languages are perfectly fine for many circumstances.
That's not a knock against anyone who does or doesn't write apps in a particular language; but folks should know what the reality is, and Objective C or Swift are by no means the only or even necessarily the most profitable ways to writes apps for OSX, though those languages are perfectly fine for many circumstances.