在另一個情節提要中快速顯示viewController

Question

我已經掙扎了一段時間。 我試圖以模態形式呈現viewController，但是每次這樣做時，都會出現以下錯誤：

libswiftCore.dylib`swift_dynamicCastClassUnconditional:
0x10f7d57d0:  pushq  %rbp
0x10f7d57d1:  movq   %rsp, %rbp
0x10f7d57d4:  testq  %rdi, %rdi
0x10f7d57d7:  je     0x10f7d580e               ; swift_dynamicCastClassUnconditional + 62
0x10f7d57d9:  movabsq $-0x7fffffffffffffff, %rax
0x10f7d57e3:  testq  %rax, %rdi
0x10f7d57e6:  jne    0x10f7d580e               ; swift_dynamicCastClassUnconditional + 62
0x10f7d57e8:  movq   0xae741(%rip), %rax       ; swift::ISAMask
0x10f7d57ef:  andq   (%rdi), %rax
0x10f7d57f2:  nopw   %cs:(%rax,%rax)
0x10f7d5800:  cmpq   %rsi, %rax
0x10f7d5803:  je     0x10f7d581d               ; swift_dynamicCastClassUnconditional + 77
0x10f7d5805:  movq   0x8(%rax), %rax
0x10f7d5809:  testq  %rax, %rax
0x10f7d580c:  jne    0x10f7d5800               ; swift_dynamicCastClassUnconditional + 48
0x10f7d580e:  leaq   0x332fd(%rip), %rax       ; "Swift dynamic cast failed"
0x10f7d5815:  movq   %rax, 0xae5cc(%rip)       ; gCRAnnotations + 8
0x10f7d581c:  int3   
0x10f7d581d:  movq   %rdi, %rax
0x10f7d5820:  popq   %rbp
0x10f7d5821:  retq   
0x10f7d5822:  nopw   %cs:(%rax,%rax)

在下面的行中：

let showItemVc = showItemStoryboard.instantiateViewControllerWithIdentifier("ShowItemViewController") as ShowItemViewController

didSelectRowAtIndexPath

func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
    if segmentedControl?.selectedSegmentIndex == 0 {


        let showItemStoryboard = UIStoryboard(name: "ShowItemStoryboard", bundle: nil)
        let showItemVc = showItemStoryboard.instantiateViewControllerWithIdentifier("ShowItemViewController") as ShowItemViewController

        self.presentViewController(showItemVc, animated: true, completion: nil)
    }
}

如果我改變就可以了

as ShowItemViewController

至

as UIViewController

但是然后我不能將值推送到ShowItemViewController，這里的問題是什么？

showItemViewController

import UIKit

class ShowItemViewController: UIViewController, UITableViewDelegate {

    @IBOutlet var pageControl: UIPageControl?
    @IBOutlet var tableView:UITableView?
    var userId: NSString?
    var itemId: NSString?

    override func viewDidLoad() {
        super.viewDidLoad()

        var no = (UIBarButtonItem(title: "Cancel", style: UIBarButtonItemStyle.Plain, target: self, action: Selector("itemCancel:")))

        self.navigationItem.leftBarButtonItem = no


        var hiddenButton = (UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Add, target: nil, action: nil))

        self.navigationItem.rightBarButtonItem = hiddenButton


        println(userId)


        self.tableView?.registerNib(UINib(nibName: "ImagePageViewCell", bundle: nil), forCellReuseIdentifier: "ImagePageViewCell")

        pageControl = UIPageControl()
        pageControl?.frame = CGRectZero
        pageControl?.currentPage = 0
        pageControl?.numberOfPages = 3
        pageControl?.tintColor = UIColor.whiteColor()
        pageControl?.userInteractionEnabled = false
        self.navigationItem.titleView = pageControl?




    }

}

Answer 1

如果要實例化其中包含ShowItemViewController的UINavigationController ，則需要對該視圖控制器的引用。 UINavigationController具有topViewController屬性，該屬性表示添加到其中的第一個子項。 如果要在ShowItemViewController填充數據，則需要此項目，並將其嵌入在導航控制器中。

let showItemStoryboard = UIStoryboard(name: "ShowItemStoryboard", bundle: nil)
let showItemNavController = showItemStoryboard.instantiateViewControllerWithIdentifier("ShowItemViewController") as UINavigationController
let showItemVC = showItemNavController.topViewController as ShowItemViewController
// Set the properties in your showItemVC
presentViewController(showItemNavController, animated: true, completion: nil)

您還應該通過執行if let XXX = YYY as? ZZZ {}檢查let實際上是否成功if let XXX = YYY as? ZZZ {} 在繼續操作之前if let XXX = YYY as? ZZZ {}跳舞，否則會出現運行時錯誤。