模型视图控制器 – 在Swift中传递数据

>为viewController2创建一个委托协议,并将viewController1设置为委托.无论何时要将数据发送回viewController1,都要让viewController2发送“委托”数据
>将一个闭包设置为允许传递数据的属性. viewController1会在显示viewController2时在viewController2上实现该关闭.每当viewController2具有要传回的数据时,它将调用闭包.我觉得这种方法比较“快”.

以下是#2的示例代码：

class ViewController2 : UIViewController {
    var onDataAvailable : ((data: String) -> ())?

    func sendData(data: String) {
        // Whenever you want to send data back to viewController1,check
        // if the closure is implemented and then call it if it is
        self.onDataAvailable?(data: data)
    }
}

class ViewController1 : UIViewController {
   func doSomethingWithData(data: String) {
        // Do something with data
    }
    override func prepareForSegue(segue: UIStoryboardSegue!,sender: AnyObject!) {
        // When preparing for the segue,have viewController1 provide a closure for
        // onDataAvailable
        if let viewController = segue.destinationViewController as? ViewController2 {
            viewController.onDataAvailable = {[weak self]
                (data) in
                if let weakSelf = self {
                    weakSelf.doSomethingWithData(data)
                }
            }
        }
    }
}