iOS: Why can't I set nil to NSDictionary value?

Question

This might be very basic question but I was wondering why can\'t I assign nil as NSDictionary value? I have following statement many places in my code. If [q objectFor

Answer 1

When using this method:

func setObject(_ anObject: Any, forKey aKey: NSCopying)

Parameters (according to Apple doc's):

anObject:

Raises an invalidArgumentException if anObject is nil. If you need to represent a nil value in the dictionary, use NSNull .

aKey

Raises an invalidArgumentException if aKey is nil.