On: Apple’s Use of Swift in iOS 13

[untog]

A guard statement requires you to actually handle the error, though. The exclamation mark will crash the app.

[saagarjha → untog]

assertionFailure is not any more "handling the error" than a forcefully unwrapping the optional.

[untog → saagarjha]

Yeah, it's also something you shouldn't do.

[saagarjha → untog]

What should you do when URL(string:) returns nil?

[RandallBrown → saagarjha]

Obviously it depends heavily on what you're doing in your app and where that string is coming from.

Is it a hard coded string that will never change? Force unwrapping is probably appropriate.

Is it based on user input? Then you should probably tell the user the string they entered isn't a URL.

[saagarjha → RandallBrown]

Right, and in that case it's pretty clear how errors can occur and what you should do to handle it.

[swatcoder → saagarjha]

That's contextual. Maybe some combination of:

- abort and unwind the current action

- retry something

- log something

- abort the app explicitly

- fallback to a different value

- comment why this is a known-possible failure state

- present a message to the user

...

[untog → saagarjha]

The one time you should unwrap it is if it's a constant - that way the app will always immediately crash if it's nil. Pretty difficult to not run into a bug like that.

But if you're creating it dynamically you should be guarding and throwing an error.