Swift中页面逆向传值

A页面 创建按钮，跳到B页面

let btn = UIButton(type: UIButtonType.Custom)self.myBtn = btnbtn.frame = CGRectMake(50, 50, 50, 50)btn.setTitle("nextVC", forState: UIControlState.Normal)btn.addTarget(self, action: "nextVC", forControlEvents: UIControlEvents.TouchUpInside)self.view.addSubview(btn)func nextVC(){     let nextVC = NextViewController()     nextVC.nextPara = {(num:Int) -> Void in         self.myBtn.setTitle("\(num)", forState: UIControlState.Normal)        }     self.navigationController?.pushViewController(nextVC, animated: true)    }

B页面 返回A页面传值

• 定义闭包

typealias loginClosure = (num:Int)->Void

• 返回按钮

 let btn = UIButton(type: UIButtonType.Custom) btn.frame = CGRectMake(50, 100, 100, 50) btn.setTitle("preVC", forState: UIControlState.Normal) btn.addTarget(self, action: "preVC", forControlEvents:  UIControlEvents.TouchUpInside) self.view.addSubview(btn)

• 传值

  func preVC(){        nextPara(num:12)    self.navigationController?.popViewControllerAnimated(true)    }