如何在 Swift 4 中显示没有 UIViewController 的新屏幕？

Question

我还没有实现 UIViewController，因为我已经从另一个 class 继承了它，它给出了 present is not member of this class

的错误

func shareAppLink() {           
    let name = "http://aijaz.com"
    let items = [name] as [Any]

    let ac = UIActivityViewController(activityItems: items, applicationActivities: nil)
    present(ac, animated: true)     
}

Answer 1

present(_:animated:completion:) 是 UIViewController 的方法，因此必须在 UIViewController.

的某种类型上调用它

如果您的 class 最初是由视图控制器创建的，那么您可以尝试使用 delegation pattern:

传递引用

Delegation is a simple and powerful pattern in which one object in a program acts on behalf of, or in coordination with, another object. The delegating object keeps a reference to the other object—the delegate—and at the appropriate time sends a message to it. The message informs the delegate of an event that the delegating object is about to handle or has just handled.

如果您为您的自定义 class 创建了一个类似这样的协议：

protocol MyClassDelegate {
    func shareAppLink()
}

然后您可以在您的视图控制器中遵守该协议并调用如下方法：delegate.shareAppLink()

Answer 2

您还可以使用 Respoder Chain 获取视图的父视图控制器

extension UIView {
    var parentViewController: UIViewController? {
        var parentResponder: UIResponder? = self
        while parentResponder != nil {
            parentResponder = parentResponder!.next
            if let viewController = parentResponder as? UIViewController {
                return viewController
            }
        }
        return nil
    }
}

并像

一样声明您的 shareAppLink 函数

func shareAppLink(sender : UIView) {
    let name = "http://aijaz.com"
    let items = [name] as [Any]
    let ac = UIActivityViewController(activityItems: items, applicationActivities: nil)
    sender.parentViewController(ac, animated: true)
}

然后在didSelectRowAt中，你可以这样称呼它：

self.shareAppLink(sender : cell)

Answer 3

你必须继承 UIViewController subclass 或 UIViewController class。通过这样做应该解决错误。

如何在 Swift 4 中显示没有 UIViewController 的新屏幕？

How to present a new screen without a UIViewController in Swift 4?

ios

swift

swift3