JSON可编码Swift 4“无”类型

Question

In response to the query, the answer "error" comes to me: None, I can not cope with assigning it to a given type. Maybe someone has a solution or an idea how to bypass this value.

My code:

import Foundation

struct Test: Codable {
let id: Int
let error: ???????

}

let json = """
{"error": None,
"id": 1
}
""".data(using: .utf8)!

let decoder = JSONDecoder()
let product = try decoder.decode(Test.self, from: json)

print(product.id)

Answer 1

First, The struct doesn't properly conform to the protocols required -> See Below.

Second to throw the error from the decoder you should try to do this;

do {
    try decoder.decode()
    // handle data here
} catch {
// handle error
}

Third, your error constant could be many things. Error() , NSError() , a custom object... If you make the error of type Error() and the value is nothing, you'll want to do an if let statement to catch a nil value and not allow the value be "None". For example:

var theError = nil
if let error = myError {
    // because you hard coded the value of error to be "None" return nil instead
    // else return the actual value of the error
    if error == "None" { return theError } else {
        theError = error
        print("error has a value! ", error.localizedDescription)
    }
} else {
     print("There is no error")
}

return theError // returns nil instead of "None" or it returns a real error