Swift popToViewController

Question

美好的一天,我正在学习Swift,需要一些帮助.

用户正在注册并选择他们的图像.在解雇图像选择器后,我想让ComposeViewController出现.

这是代码:

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)
}

然后我收到这些错误:ComposeViewController.Type'不能转换为'UIViewController预期的成员名或类型名称后的构造函数调用

它有建议通过在ComposeViewController之后put()来修复,但是在修复之后它会发出更多错误.

希望有人能提供帮助.谢谢!:-)

Answer 1

我知道这是旧的,但它就像Saqib所说的那样,你不能弹出一个尚不存在的viewcontroller.

这里的很多答案似乎来自那些没有阅读你的问题的人,只有标题.我会在这里留下这些代码以防万一它可以帮助任何人.

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 2

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

Answer 3

导航控制器维护您正在推送的视图堆栈。它就像一个后进先出队列。

为了弹出到 ComposeViewController，该视图必须已存在于队列中，并且您应该可以引用它。

您将需要传递 ComposeViewController 的实例。为简单起见，您可以将该引用保存在 appdelegate 中。（不推荐这种方法）