通过 navigationController 使用 segue 传递数据

Question

我正在尝试将数据从一个 viewController 推送到另一个。我已经将一个viewController 连接到另一个ViewController 的navigationController，然后将标识符设置为"showItemSegue"。我在这两行中遇到错误：

var detailController = segue.destinationViewController as ShowItemViewController
detailController.currentId = nextId!

图片说明：

代码：

override func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {


    nextId = itemArray?.objectAtIndex(indexPath.row).objectForKey("objectId") as? NSString

    self.performSegueWithIdentifier("showItemSegue", sender: self)

}


override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject!) {

    if (segue.identifier == "showItemSegue") {
        var detailController = segue.destinationViewController as ShowItemViewController
        detailController.currentId = nextId!
    }

}

Answer 1

segue 的目标视图控制器是UINavigationController。您需要询问它的顶部视图控制器才能到达真正的目标视图控制器：

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "showItemSegue" {
        let navController = segue.destination as! UINavigationController
        let detailController = navController.topViewController as! ShowItemViewController
        detailController.currentId = nextId!
    }
}