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Asked: 2024-09-22T16:53:29+05:30

How can you handle a scenario in Swift 4 where a Codable property can be represented as either a Boolean or a String in JSON? What approaches can be taken to manage this type of variability in data during encoding and decoding?

Hey everyone! I came across a tricky scenario while working with JSON data in Swift 4, and I’m hoping to get your insights on it.

Imagine you have a `User` struct that includes a property representing a user’s status, which can either be a Boolean (true/false) or a String (like “active” or “inactive”) in the JSON response. Here’s a simple example:

“`swift
struct User: Codable {
var name: String
var isActive: Bool
}
“`

In this case, the `isActive` property can be encoded as either:

“`json
{
“name”: “John Doe”,
“isActive”: true
}
“`
or
“`json
{
“name”: “John Doe”,
“isActive”: “active”
}
“`

I’m wondering what approaches you would take to handle this variability in data during both encoding and decoding? Has anyone dealt with something similar and found an elegant solution? Any code snippets or ideas to share would be greatly appreciated! Thanks!

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    2 Answers






    1. Handling JSON with Variable Types in Swift

      Handling Variable JSON Types in Swift

      Hey! I totally understand the situation you’re facing with the JSON data in Swift. When dealing with a property that can be either a Bool or a String, using a custom implementation of the Codable protocol can help you manage this variability. Here’s a simple approach you can take:

      Define an Enum for Status

      First, you can create an enum to define the possible values for the user’s status:

      enum UserStatus: Codable {
    case active
    case inactive
    case isActive(Bool)

    enum CodingKeys: String, CodingKey {
        case active
        case inactive
    }

    init(from decoder: Decoder) throws {
        let container = try decoder.singleValueContainer()
        if let boolValue = try? container.decode(Bool.self) {
            self = .isActive(boolValue)
        } else if let stringValue = try? container.decode(String.self) {
            self = stringValue == "active" ? .active : .inactive
        } else {
            throw DecodingError.dataCorruptedError(in: container, debugDescription: "Invalid status value")
        }
    }

    func encode(to encoder: Encoder) throws {
        var container = encoder.singleValueContainer()
        switch self {
        case .isActive(let boolValue):
            try container.encode(boolValue)
        case .active:
            try container.encode("active")
        case .inactive:
            try container.encode("inactive")
        }
    }
}

      Update the User Struct

      Next, update your User struct to include the new UserStatus type:

      struct User: Codable {
    var name: String
    var status: UserStatus
}

      Example Usage

      Here’s how you can decode JSON with this setup:

      let jsonData = """
    {
        "name": "John Doe",
        "status": "active"
    }
    """.data(using: .utf8)!

do {
    let user = try JSONDecoder().decode(User.self, from: jsonData)
    print(user)
} catch {
    print("Error decoding JSON: \(error)")
}

      Conclusion

      This approach allows you to handle both the Boolean and String formats for the user’s status efficiently. You just need to encode and decode based on the respective types. Hope this helps!



    2. Handling a `User` struct where the `isActive` property can either be a Boolean or a String requires a custom implementation of the Codable protocol. In the decoding phase, one approach is to create a custom initializer that assesses the type of the input data. You can use a combination of try/catch to safely attempt decoding first as a Bool, and if that fails, fall back to decoding as a String. To encode, you could implement a computed property that returns the value as a Bool, ensuring that it is always serialized as either true or false based on the string values. Below is an example of how this can be done:

          struct User: Codable {
        var name: String
        var isActive: Bool

        enum CodingKeys: String, CodingKey {
            case name
            case isActive
        }

        init(from decoder: Decoder) throws {
            let container = try decoder.container(keyedBy: CodingKeys.self)
            name = try container.decode(String.self, forKey: .name)
            if let activeStatus = try? container.decode(Bool.self, forKey: .isActive) {
                isActive = activeStatus
            } else {
                let statusString = try container.decode(String.self, forKey: .isActive)
                isActive = (statusString.lowercased() == "active")
            }
        }

        func encode(to encoder: Encoder) throws {
            var container = encoder.container(keyedBy: CodingKeys.self)
            try container.encode(name, forKey: .name)
            try container.encode(isActive, forKey: .isActive)
        }
    }

      By implementing custom decoding logic, we can gracefully manage the variability of the JSON response. This allows your application to correctly interpret and convert the `isActive` property’s value regardless of its format in the incoming data. Additionally, it simplifies the encoding process, preserving the Boolean logic while preparing the object for serialization back to JSON. This approach offers flexibility while ensuring type safety in your Swift models, making it a strong solution for scenarios with inconsistent data types.


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