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how do i check if a BOOL is set in objective-c (iphone)?
i know that it can be done with an int or float this way: NSNumber *Num = [prefs floatForKey:@"key"]; for example
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You can't. A BOOL is either YES or NO . There is no other state.
Nil is not a Bool. phoneyDev: The error states that the Bool? has not been unwrapped. That's what optional chaining does.
Optional binding The code let booleanValue = booleanValue returns false if booleanValue is nil and the if block does not execute. If booleanValue is not nil , this code defines a new variable named booleanValue of type Bool (instead of an optional, Bool? ).
To check if a value is of boolean type, check if the value is equal to false or equal to true , e.g. if (variable === true || variable === false) . Boolean values can only be true and false , so if either condition is met, the value has a type of boolean. Copied!
You can't. A BOOL is either YES or NO. There is no other state. The way around this would be to use an NSNumber ([NSNumber numberWithBool:YES];), and then check to see if the NSNumber itself is nil. Or have a second BOOL to indicate if you've altered the value of the first.
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Annoyingly, Objective-C has no Boolean class. It certainly feels like it should and that trips a lot of people up. In collections and core data, all bools are stored as NSNumber instances.
It's really annoying having to convert back and forth all the time.
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