ARC Retain Cycle Test

Test.swift

class TestObj:UIView {
    var done:(()->())!
    deinit {
        println("deinit TestObj")
    }
    func doNothing2(){
        
    }
    func doNothing(){
        self.doNothing2()
    }
    func goAnimate(){
        weak var wself:TestObj! = self
        UIView.animateWithDuration(0.2, animations: {() -> Void in
            self.frame = CGRectMake(0, 0, 10, 10)
        })
        println("done")
        dispatch_async( dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), { () -> Void in
            self.doNothing()
        })
        
        var doneBlock:()->() = {[weak self] in
            self?.doNothing2()
        }
        self.done = doneBlock 
        doneBlock()
    }
}


  var test:TestObj! = TestObj()
  test.goAnimate()
  test = nil
  
  
  上面只有doneBlock 在 self.done = doneBlock 之后，自己持有了doneblock 的对象之后，才会有 retain cycle。
  如果没有 self.done = doneBlock
  var doneBlock:()->() = { in
            self.doNothing2()
        }
  doneBlock()
  也不会发生 retain cycle