> Le 14 juin 2014 à 21:45, Roland King <r...@rols.org> a écrit : > > My current understanding is that you can access their value directly, without > using the 'if let' syntax or the explicit unwrap (!) operator, but you'll > crash if the optional doesn't have a value when you do. You can also treat > them like an optional and using 'if' on them tells you if they exist just > like an optional does.
That’s seems fairly correct. > var date : NSDate! > > First question is why use an implicitly unwrapped optional instead of just an > optional? You still have to test them so what do you gain? If my understanding is correct, the IUO (that’s shorter) is assumed to have a valid value once it has been initialized (it should never return to nil). Therefore, it’d be superfluous to test it each time you encounter it. You can therefore write: var anotherReferenceOnDate : NSDate = date directly, whereas with a regular optional you’d have to use the ! everywhere: var anotherReferenceOnDate : NSDate = date! > I assume the slide is being a little sloppy and that really means use the > normal "if xxx" syntax for these which returns true if the value exists, as > xxx == nil would surely attempt an unwrap and throw if the value didn't exist. I guess so. > Finally if you have an implicitly optional Bool, bbb, what does > > if bbb > > do? Does it return whether bbb has a value or does it return the unwrapped > value of the Bool used in the if? I assume the former in which case how do > you use an implicitly unwrapped optional bool in an if? Good riddle. Did you try in a playground? Vincent _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
