Swift 3 在其定义模块之外覆盖非开放变量

Question

我将我的 swift 2 代码转换为 swift 3。然后我收到了这个错误。谁能帮我解决这个问题？

open override var formatKey: String { //overriding non-open var outside of its defining module
    get {
        if customFormatKey != nil {
            return customFormatKey!
        }
        return String(describing: type(of: self)).components(separatedBy: ".").last!
    }
}

Answer 1

根据 The Swift Programming Language 的访问控制部分:

Open access applies only to classes and class members, and it differs from public access as follows:

• Classes with public access, or any more restrictive access level, can be subclassed only within the module where they’re defined.

• Class members with public access, or any more restrictive access level, can be overridden by subclasses only within the module where they’re defined.

• Open classes can be subclassed within the module where they’re defined, and within any module that imports the module where they’re defined.

• Open class members can be overridden by subclasses within the module where they’re defined, and within any module that imports the module where they’re defined.

open 在 Swift 3 及更高版本中等同于 public 在 Swift 2 中。有关更多信息，请参阅 Swift Evolution proposal SE-0117 .

要解决此问题，请将 formatKey 的原始定义从 public 更改为 open，并使用 override var formatKey: String 进行覆盖{ ...。