用prepareForSegue Swift传递对象 [英] Passing object with prepareForSegue Swift

问题描述

我正在尝试将对象传递给另一个场景 prepareForSegue（）

I am trying to pass an object to another scene with prepareForSegue()

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        // Get the new view controller using [segue destinationViewController].
        var nextScene =  segue.destinationViewController as! VehicleDetailsTableViewController

        // Pass the selected object to the new view controller.
        if let indexPath = self.tableView.indexPathForSelectedRow() {
            let selectedVehicle = vehicles[indexPath.row]
            nextScene.currentVehicle = selectedVehicle
        }
    }

我有currentVehicle对象来捕获这些对象。但是，当我试图运行时，它会破坏并获得有关向下转换的错误。

And I have currentVehicle object to catch these object. But, when I try to run, it brokes and get error about downcasting.

错误编辑

无法将'XXX.DisplayViewController'
（0x1082dcd80）类型的值转换为'XXX.VehicleDetailsTableViewController'
（0x1082dc9a0）。 （lldb）

Could not cast value of type 'XXX.DisplayViewController' (0x1082dcd80) to 'XXX.VehicleDetailsTableViewController' (0x1082dc9a0). (lldb)

推荐答案

你必须在故事板中给segue一个标识符。 mySegue ）

You have to give the segue an identifier in the storyboard.(say mySegue)

使用XCode 7，swift 2.x

 override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?){....}

调用从当前 UIViewController 调用的所有segue。所以标识符用于区分不同的segue

Is called for all segues being called form your current UIViewController. So the identifier is to differentiate the different segues

然后使用此代码：

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if segue.identifier == "mySegue" {
    var nextScene =  segue.destinationViewController as! VehicleDetailsTableViewController

    // Pass the selected object to the new view controller.
    if let indexPath = self.tableView.indexPathForSelectedRow {
        let selectedVehicle = vehicles[indexPath.row]
        nextScene.currentVehicle = selectedVehicle
    }
  }
}

使用Xcode 9，swift 4.x（也适用于Xcode 8& swift 3.x）

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "mySegue" , 
       let nextScene = segue.destination as? VehicleDetailsTableViewController , 
       let indexPath = self.tableView.indexPathForSelectedRow {
        let selectedVehicle = vehicles[indexPath.row]
        nextScene.currentVehicle = selectedVehicle
    }
}

在 nextScene 之后放置一个断点，看看它是否正在通过单击 TableView 中的任何单元格触发。如果不是，那么故事板中提供的标识符名称必须与此处给出的名称不同。

Place a breakpoint after nextScene and see if it is being triggered by clicking any cell in the TableView. If it isn't then the identifier name u provided in the storyboard must be different then the one given here.

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