Reference to a protocol inside a class throughs the following error: Expected member name or constructor call after type name

Question

这是我目前的情况：

class FirstViewController: UITableViewController {
   ...
}

protocol SharedFunctions {
   func createEvent(event: Event, text: String)
}

extension FirstViewController: SharedFunctions {
   createEvent(event: Event, text: String) {
       ...
   }
}

class SecondViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
   var sharedFunctions = SharedFunctions? // < Xcode error...

   @IBAction func postChatMessageAction(_ sender: Any) {
       self.sharedFunctions.createEvent(event: event, text: "New Event")
   }
   ...
}

Error: Expected member name or constructor call after type name

当我更改我的代码时 Xcode 提示错误已消失，但我在 createEvent 函数上遇到错误

var sharedFunctions = SharedFunctions?.self //Xcode suggestion is adding .self

现在我在 createEvent 函数上遇到错误

@IBAction func postChatMessageAction(_ sender: Any) {
   self.sharedFunctions.createEvent(event: event, text: "New Event") // < Xcode error...
}

Error: Type 'SharedFunctions?' has no member 'createEvent'

我也尝试了以下错误：

weak var delegate = SharedFunctions? // < Xcode error...

Error: 'weak' may only be applied to class and class-bound protocol types, not 'SharedFunctions?.Type'

我想做的是，从我的 SecondViewController class 我想触发我的 FirstViewController class.

中的函数 createEvent()

Answer 1

您的 SharedFunctions 声明语法错误。应该是

weak var delegate: SharedFunctions?

Answer 2

尝试

class SecondViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {

   //Need change here
   var sharedFunctions : SharedFunctions? // < Xcode error...

     @IBAction func postChatMessageAction(_ sender: Any) {
      self.sharedFunctions.createEvent(event: event, text: "New Event")
     }
   ...
  }

Answer 3

首先，FirstViewController 的扩展中缺少一个 func 关键字。尝试像这样实现 createEvent(event:text:) 函数：

extension FirstViewController: SharedFunctions {
   func createEvent(event: Event, text: String) {
       ...
   }
}

除此之外，SecondViewController中sharedFunctions属性的声明是错误的。请尝试以下操作：

class SecondViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
   var sharedFunctions: SharedFunctions?

   @IBAction func postChatMessageAction(_ sender: Any) {
       self.sharedFunctions.createEvent(event: event, text: "New Event")
   }
   ...
}

希望对您有所帮助。

Reference to a protocol inside a class throughs the following error: Expected member name or constructor call after type name

Reference to a protocol inside a class throughs the following error: Expected member name or constructor call after type name

xcode

class

swift

swift-protocols