So what happens if it ends up being nil? How does your app react?
In this particular case, I would rather crash. It’s easier to spot in a crash report and you get a nice stack trace.
Silent failure is ultimately terrible for users.
Note: for the things I control I try to very explicitly model state in such a way as I never need to force unwrap at all. But for things beyond my control like this situation, I would rather end the program than continue with a state of the world I don’t understand.
Yeah @IBOutlets are generally the one thing that are allowed to be implicitly-unwrapped optionals. They go along with using storyboards & xibs files with Interface Builder. I agree that you really should just crash if you are attempting to access one and it is nil. Either you have done something completely incorrect with regards to initializing and accessing parts of your UI and want to catch that in development, or something has gone horribly, horribly, horribly with UIKit/AppKit and storyboard/xib files are not being loaded properly by the system.
A good tool for catching stuff during development, is the humble assert()[0]. We can use precondition()[1], to do the same thing, in ship code.
The main thing is, is to remain in control, as much as possible. Rather than let the PC leave the stack frame, throw the error immediately when it happens.
> Silent failure is ultimately terrible for users.
Agreed.
Unfortunately, crashes in iOS are “silent failures,” and are a loss of control.
What this practice does, is give me the option to handle the failure “noisily,” and in a controlled manner; even if just emitting a log entry, before calling a system failure. That can be quite helpful, in threading. Also, it gives me the option to have a valid value applied, if there’s a structural failure.
But the main reason that I do that with @IBOutlets, is that it forces me to acknowledge, throughout the rest of the code, that it’s an optional. I could always treat implicit optionals as if they were explicit, anyway. This just forces me to.
I have a bunch of practices that folks can laugh at, but my stuff works pretty effectively, and I sleep well.
Crashes are silent failures but as I mentioned: you can get a lot of your crashes reported via the App Store. This is why I prefer crashes in this situation: it gives me something actionable over silent failures on the client.
And you will find the problem very early if you crash. You are much less likely to find the problem if you don’t.
What have you found useless about the crash reports from the App Store? It would be really nice for it to have something like a breadcrumb capability, but typically the stack trace of the crash is sufficient to see what went wrong.
In this particular case, I would rather crash. It’s easier to spot in a crash report and you get a nice stack trace.
Silent failure is ultimately terrible for users.
Note: for the things I control I try to very explicitly model state in such a way as I never need to force unwrap at all. But for things beyond my control like this situation, I would rather end the program than continue with a state of the world I don’t understand.