Add assert while unwrapping optional in swift

Asked Nov 26 '17 at 14:39

Active Nov 26 '17 at 15:15

Viewed 242 times

I have an optional value, and I want to add an assert if the value is nil. So, I want to do something like:

if let val = val {
    ...
} else {
    assertionFailure("No fields for key \(my dictionary key)")
}

My question is, will the assertionFailureabove result in a crash in my production app?

edited Nov 26 '17 at 15:15

Paulo Mattos

asked Nov 26 '17 at 14:39

Evgeniy Kleban

Have you read through the documentation https://developer.apple.com/documentation/swift/1539616-assertionfailure ? – luk2302 Nov 26 '17 at 14:48
@luk2302 i had but understand nothing. – Evgeniy Kleban Nov 26 '17 at 14:49
What is unclear about *"Use this function to stop the program, **without impacting the performance of shipping code,** ..."* and *"In -O builds, has **no effect.**"* ? – Martin R Nov 26 '17 at 15:01
And To protect code from invalid usage in Release builds, see preconditionFailure – Leo Dabus Nov 26 '17 at 15:01
@MartinR what is -O build? – Evgeniy Kleban Nov 26 '17 at 15:02
Have a look at https://stackoverflow.com/a/34379407/1187415. – "-O" is "with optimization", and that is how the archives for app store release are built. – Martin R Nov 26 '17 at 15:05
Possible duplicate of [Difference between “precondition” and “assert” in swift?](https://stackoverflow.com/questions/29673027/difference-between-precondition-and-assert-in-swift). – Martin R Nov 26 '17 at 15:23
@MartinR ok, thanks you. – Evgeniy Kleban Nov 26 '17 at 15:31
What will you do differently in your production app when the optional binding fails? – rmaddy Nov 26 '17 at 16:48

0 Answers0