In a capture list, there is no need to capture a reference to "self" if you need a reference to an instance self holds. https://twitter.com/qnoid/status/690507191057551360

ViewController.swift

class ViewController : UIViewController
{
  var foo = "foo"

  func hello()
  {
    let closure = { [foo = self.foo] in
      print("Hello \(foo)!") 
    }
  }
}

“Capture Lists
By default, a closure expression captures constants and variables from its surrounding scope with strong references to those values. You can use a capture list to explicitly control how values are captured in a closure.”

Excerpt From: Apple Inc. “The Swift Programming Language (Swift 2.1).” iBooks. https://itun.es/gb/jEUH0.l