Convert string JSON response to a boolean using Swift 4 Decodable

Question

I'm refactoring some projects where I'd previously used third-party JSON parsers and I've encountered a goofy site that returns a boolean as a string.

This is the relevant snippet from the JSON response:

{
    "delay": "false",
    /* a bunch of other keys*/
}

My struct for Decoding looks like this:

struct MyJSONStruct: Decodable {
  let delay: Bool
  // the rest of the keys
}

How would I convert the string returned in the JSON response into a Bool to match my struct in Swift 4? While this post was helpful, I can't figure out how to turn a string response into a boolean value.

override `init(decoder: Decoder)` and manually handle ALL of the decoding. I say all because you can't optionally decode some fields and not others. — Brandon, Oct 20 '17 at 13:24
Ouch. I've got ~20 keys with some nested structs, all for one boolean. — Adrian, Oct 20 '17 at 13:28

vadian · Accepted Answer · 2020-03-25T07:40:38.407

10

Basically you have to write a custom initializer but if there are many good keys but only one to map from a type to another a computed property might be useful

struct MyJSONStruct: Decodable {
   var delay: String
   // the rest of the keys

   var boolDelay : Bool {
       get { return delay == "true" }
       set { delay = newValue ? "true" : "false" }
   }
}

edited Mar 25 '20 at 07:40

answered Oct 20 '17 at 13:34

vadian

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Oh! That's brilliant! I'd rather add 3 lines of code than a custom initializer. Thank you! – Adrian Oct 20 '17 at 13:37
@LeoDabus I changed the `let` to a `var`. Thanks again for this simple workaround. – Adrian Oct 20 '17 at 13:43

score 1 · Answer 2 · answered Feb 12 '20 at 11:44

1

you need to set the boolEncoding: .literal in the URLEncoding initializer.

boolEncoding: .literal

answered Feb 12 '20 at 11:44

Akshay Khadke

121
3

Convert string JSON response to a boolean using Swift 4 Decodable

2 Answers2

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