How to capture a variable's current value for a block

Question

Is there a way to save the current value of a varible for later usage in a block?

For example, for this Playground code:

import UIKit
import XCPlayground         


        

Answer 1

You can bind an arbitrary expression to a named value in a capture list, the expression is evaluated when the closure is created. In your case you would bind self.i:

dispatch_after(dispatchTime, dispatch_get_main_queue(), { [i = self.i] in
    self.test(i)
})

Answer 2

Since you're referencing i through a captured self, you will get whatever the value is at dispatch time. If you want to capture the value as it is at the beginning of the function, you'll need to get a local copy before changing it.

    let x = self.i
    dispatch_after(dispatchTime, dispatch_get_main_queue(), {
        self.test(x)
    })