Create an optional block as a variable

Question

I have a simple class where I declare a block as a variable:

class MyObject : NSObject 
{
    var progressBlock:(progress:Double) -> ()?

    init() { }
}         


        

Answer 1

The way you have written it, the compiler assumes progressBlock is a closure that returns an optional empty tuple instead of an optional closure that returns an empty tuple. Try writing it like this instead:

class MyObject:NSObject {
    var progressBlock:((progress:Double) -> ())?
    init() {
        progressBlock = nil
        progressBlock = { (Double) -> () in /* code */ }
    }
}