How to check if a variable is nil

Question

I have a variable

var a: [AnyObject? -> Void] 

and I am adding data in to it by append method. Now I want to check if the variable is nil or not. I tried using [] but not working and also tried "", this also not working, can anyone tell what is the meaning of this variable and how to check if it is nil.

Answer 1

As far as I understand, var a is an Array of functions that take an optional Object of any type, and return void. So these functions's parameter IS optional, but the Array itself isn't : it cannot be nil, or it would be declared [AnyObject? -> Void]? , no?

EDIT : if, nevertheless, you declared this a as an optional (but WHY would you do that ?) - adding a ? - you check an optional existence with if let :

if let b = a {
// a not nil, do some stuff
} else {
// a is null
}

If you just want to check if the array is empty, use isEmpty method from Swift Array