Swift popToViewController

Question

大家好，我正在学习Swift，这里需要一些帮助。

用户正在注册并选择他们的图像。关闭图像选择器后，我希望显示ComposeViewController。

代码如下：

func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: NSDictionary!) {
    let pickedImage:UIImage = info.objectForKey(UIImagePickerControllerOriginalImage) as UIImage

    //Scale Down Image
    let scaledImage = self.scaleImageWith(pickedImage, and: CGSizeMake(100,100))

    let imageData = UIImagePNGRepresentation(scaledImage)

    let imageFile:PFFile = PFFile(data: imageData)

    PFUser.currentUser().setObject(imageFile, forKey: "profileImage")
    PFUser.currentUser().saveInBackgroundWithTarget(nil, selector: nil)

    picker.dismissViewControllerAnimated(true, completion: nil)

    //this is the line seems to have problem.
    self.navigationController?.popToViewController(ComposeViewController, animated: true)
}

然后我得到了这些错误:不能将ComposeViewController.Type‘转换为'UIViewController’预期的成员名称或类型名称后的构造函数调用

它建议通过将()放在ComposeViewController之后来进行修复，但是在修复之后它会给出更多的错误。

希望有人能帮忙。谢谢！:-)

Answer 1

let controllers = self.navigationController?.viewControllers
              for vc in controllers! {
                if vc is YourVC {
                  _ = self.navigationController?.popToViewController(vc as! YourVC, animated: true)
                }
             }

Answer 2

我知道这很老，但就像Saqib所说的，你不能弹出一个还不存在的视图控制器。

这里的许多答案似乎来自没有读过你的问题的人，只是标题。我将把这段代码留在这里，以防它对任何人有帮助。

let vcIndex = self.navigationController?.viewControllers.indexOf({ (viewController) -> Bool in

    if let _ = viewController as? ComposeViewController {
        return true
    }
    return false
})

let composeVC = self.navigationController?.viewControllers[vcIndex!] as! ComposeViewController

self.navigationController?.popToViewController(composeVC, animated: true)

Answer 3

有一个方法可以让您访问当前堆栈上所有ViewControllers的数组，您可以通过使用它的索引来捕获您想要的数组，例如：

let switchViewController = self.navigationController?.viewControllers[1] as! ComposeViewController

self.navigationController?.popToViewController(switchViewController, animated: true)