Swift Tutorial - Swift Assertions

Assertions can help with your debugging efforts.

Assertions work by testing a condition to see whether the condition is satisfied.

If the condition is false, then a runtime error occurs, and the program stops executing.

Assertions may have an optional message that is printed in the console window when the condition is false.


To create an assertion, write the assertion shown as follows.

var myValue = 4
assert(myValue == 3, " myValue must be three ")

The assert statement in the code above is testing to make sure that the myValue variable has the correct number.

Assertions are tested only in Debug mode.