使用@AppStorage的字典扩展

Question

我知道在使用带有@AppStorage的字典时，我需要使Dictionary与RawRepresentable保持一致。下面是我所得到的最远的。

extension Dictionary: RawRepresentable where Key == String, Value == String {
    public init?(rawValue: String) {
        guard let data = rawValue.data(using: .utf8),  // convert from String to Data
            let result = try? JSONDecoder().decode([String:String].self, from: data)
        else {
            return nil
        }
        self = result
    }

    public var rawValue: String {
        guard let data = try? JSONEncoder().encode(self),   // data is  Data type
              let result = String(data: data, encoding: .utf8) // coerce NSData to String
        else {
            return "[:]"  // empty Dictionary respresented as String
        }
        return result
    }

}

扩展编译。但是，当我声明一本空字典时，它就没用了：

@AppStorage private var data :  [String:String] = [:]

错误消息是Missing argument for parameter #2 in call

密码怎么了？

Answer 1

您丢失了存储的字符串键：

@AppStorage("data") private var data :  [String:String] = [:]