Cast closures/blocks

Question

In Objective-C, I often pass around blocks. I use them very often to implement patterns that help avoid storing stuff into instance variables, thus avoiding threading/timing

Answer 1

All you need to do is use reinterpretCast to perform force cast.

(reinterpretCast(completion) as (@objc_block Void -> Void))()

from REPL

  1> import Foundation
  2> var block : @objc_block Void -> Void = { println("test")}
block: @objc_block Void -> Void =
  3> var obj = reinterpretCast(block) as AnyObject // this is how to cast block to AnyObject given it have @objc_block attribute
obj: __NSMallocBlock__ = {}
  4> var block2 = reinterpretCast(obj) as (@objc_block Void -> Void)
block2: (@objc_block Void -> Void) =
  5> block2()
test
  6>