使用 int 值将枚举编码为字符串

Posted 2023-02-15

【中文标题】使用 int 值将枚举编码为字符串

【英文标题】：Encoding enum with int values as String

【发布时间】：2022-01-17 02:27:44

【问题描述】：

我正在使用 Flutter 为 android 和 ios 开发一个使用蓝牙的应用程序。 Android 和 Flutter 部分已经在运行，iOS 只剩下一小部分。目前我在将蓝牙属性发送到 Flutter 平台时遇到问题。我正在阅读它们，使用 int 值枚举来存储它们并使用 Json 对它们进行编码以将它们发送到 EventChannel。我的问题是我想以字符串形式发送它们，例如，如果属性如下：PROPERTY_WRITE = 8，它应该在 Json 中编码为“PROPERTY_WRITE”。你可以在下面看到我的代码：

enum BLEProperty: UInt, Codable 
    case PROPERTY_BROADCAST = 1
    case PROPERTY_EXTENDED_PROPS = 128
    case PROPERTY_INDICATE = 32
    case PROPERTY_NOTIFY = 16
    case PROPERTY_READ = 2
    case PROPERTY_SIGNED_WRITE = 64
    case PROPERTY_WRITE = 8
    case PROPERTY_WRITE_NO_RESPONSE = 4


extension BLEProperty 
    private enum CodingKeys: String, CodingKey 
        case PROPERTY_BROADCAST
        case PROPERTY_EXTENDED_PROPS
        case PROPERTY_INDICATE
        case PROPERTY_NOTIFY
        case PROPERTY_READ
        case PROPERTY_SIGNED_WRITE
        case PROPERTY_WRITE
        case PROPERTY_WRITE_NO_RESPONSE
    
    
    func encode(to encoder: Encoder) throws 
        var container = encoder.container(keyedBy: CodingKeys.self)
        switch self 
        case .PROPERTY_BROADCAST:
            try container.encode(BLEProperty.PROPERTY_BROADCAST, forKey: .PROPERTY_BROADCAST)
        case .PROPERTY_EXTENDED_PROPS:
            try container.encode(BLEProperty.PROPERTY_EXTENDED_PROPS, forKey: .PROPERTY_EXTENDED_PROPS)
        case .PROPERTY_INDICATE:
            try container.encode(BLEProperty.PROPERTY_INDICATE, forKey: .PROPERTY_INDICATE)
        case .PROPERTY_NOTIFY:
            try container.encode(BLEProperty.PROPERTY_NOTIFY, forKey: .PROPERTY_NOTIFY)
        case .PROPERTY_READ:
            try container.encode(BLEProperty.PROPERTY_READ, forKey: .PROPERTY_READ)
        case .PROPERTY_SIGNED_WRITE:
            try container.encode(BLEProperty.PROPERTY_SIGNED_WRITE, forKey: .PROPERTY_SIGNED_WRITE)
        case .PROPERTY_WRITE:
            try container.encode(BLEProperty.PROPERTY_WRITE, forKey: .PROPERTY_WRITE)
        case .PROPERTY_WRITE_NO_RESPONSE:
            try container.encode(BLEProperty.PROPERTY_WRITE_NO_RESPONSE, forKey: .PROPERTY_WRITE_NO_RESPONSE)
        
    

【参考方案1】：

您可以添加一个返回枚举案例名称的计算属性，然后encode(to:) 函数变得更加简单

extension BLEProperty 
    var propertyName: String 
        "\(self)"
    

    func encode(to encoder: Encoder) throws 
        var container = encoder.singleValueContainer()
        try container.encode(self.propertyName)
    

例子

let properties: [BLEProperty] = [.PROPERTY_READ, .PROPERTY_BROADCAST]

do 
    let data = try JSONEncoder().encode(properties)
    if let string = String(data: data, encoding: .utf8)  print(string) 
 catch 
    print(error)

["PROPERTY_READ","PROPERTY_BROADCAST"]

【讨论】：

谢谢 Joakim，这是完美的解决方案！