InnerFunctions.swift

import Foundation

var a = 0

let closure = {
    return a
}

a = 1

closure.dynamicType

closure() //returns 1. Captures a reference to the variable.

func innerFunction() -> Int {
    var a = 0
    
    func inner() -> Int {
        return a
    }
    
    a = 1
    
    return inner()
}

innerFunction.dynamicType //Dynamic Type matches

innerFunction() //returns 1. Captures a reference to the variable.
//It's exactly the same as the previous closure.

let valueCapturingClosure = {[a] in
    return a
}

a = 2

valueCapturingClosure.dynamicType //Dynamic Type matches

valueCapturingClosure() //returns 1. Captures the value, not the reference.