Non-Null Assertion Operator

Overview

So far, we haven’t talked about how to fix the kind of errors that are triggered by strict null checks. The reason I haven’t mentioned a non-null assertion operator is that you shouldn’t be using it unless you have a very good reason to do so.

Non-null assertion operators are simply a way of telling the compiler, trust me, I’m absolutely sure that this optional value is in fact never empty. Syntactically, you can express this by postfixing the optional value with a ! character.