ios - 如何在闭包中访问类的变量？

Question

我读了这个主题:Swift accessing class variable inside closures .但对我没有帮助。

问题

我有一个 ViewControllerData 来显示数据，还有一个 ViewControllerEdit 来编辑数据。我想将对象从 ViewControllerData 发送到 ViewControllerEdit，我使用 performSegue 来实现，但我无法从 获取编辑后的对象查看 Controller 编辑。我想在 prepare 函数中像参数一样传递闭包 (funcReturnFromEdit)。

class ViewControllerData: UIViewController, UITableViewDataSource, UITableViewDelegate {

    @IBOutlet weak var tableViewData: UITableView!
    var saleOrder : SaleOrder?  // THIS! <--------

    // In this closure I want take the edited object.
    let funcReturnFromEdit = { (saleEdited : SaleOrder) -> () in
        self.saleOrder = saleEdited // I can't do this. Error: Value of type '(ViewControllerData) -> () -> (ViewControllerData)' has no member 'saleOrder'
    }

    ....

      override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        segue.identifier == "segueEditOrder" {
        let editVc = segue.destination as! ViewControllerEdit
        if saleOrder != nil {
            editVc.saleOrderToEdit = saleOrder!.copy() as! SaleOrder
        }
        editVc.funcReturn = self.funcReturnFromEdit // <-- Not works
    }
}

错误是:实例成员“saleOrder”不能用于类型“ViewControllerData”

除此之外，我不知道如何在 ViewControllerEdit 上创建此功能

class ViewControllerEdit: UIViewController, UITableViewDelegate, UITableViewDataSource {

    var saleOrderToEdit : SaleOrder?

    var funcReturn = { (SaleOrder) -> Void in {} } // <- This not compile. How to do this?

    ...
    /*
     Funcs to make edition...
    */

    func endEditions() {
        funcReturn(saleOrderToEdit) // <- Here I want send to back ViewControllerData
    }
}

Answer 1

如果你需要在闭包中使用全局变量/方法，请在你的变量/方法之前放置self.

所以你可以替换这个

saleOrder = saleEdited

与

self.saleOrder = saleEdited

但看起来问题也在其他地方。您只需要将 saleOrder 从第一个传递到第二个 ViewController，然后在其中编辑它，然后将数据传递回第一个 View Controller

因此，首先从 ViewControllerData 中删除不必要的代码:

let funcReturnFromEdit = { (saleEdited : SaleOrder) -> () in
    saleOrder = saleEdited // I can't do this. 
}

并修复 ViewControllerEdit 中的完成处理程序替换

var funcReturn = { (SaleOrder) -> Void in {} }

与

var funcReturn : ((SaleOrder) -> ())?

还要编辑您的 endEditions 方法，因为 funcReturn 是可选的

func endEditions() {
    funcReturn?(saleOrderToEdit)
}

现在只需在您的 ViewControllerData 中修复 prepare 方法来设置当用户从 ViewControllerEdit 调用 funcReturn 时应该做什么

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "segueEditOrder" {
        let editVc = segue.destination as! ViewControllerEdit
        if let saleOrderToPass = saleOrder {
            editVc.saleOrderToEdit = saleOrderToPass
            editVc.funcReturn = { saleEdited in
                self.saleOrder = saleEdited //This code is executed when you call funcReturn?(saleOrderToEdit) from ViewControllerEdit
            }
        }
    }
}