Decodable and CGPoint

I tried this code in a playground:

var circle = Circle (center: CGPoint (x: 129, y: 94), radius: 73)
let encoder = JSONEncoder ()
let encodedData = try! encoder.encode (circle)
let encodedString = String (bytes: encodedData, encoding: .utf8)!
print (encodedString)

and the output was:

{"center":[129,94],"radius":73}

So it looks like CGPoint has a custom implementation of Codable that represents the coordinates as a vector rather than a struct. I'm not sure what I think about that, since it's not documented anywhere. I did find this, though:

medium.com/swiftly-swift/little-xcode-beta-surprises-core-graphics-codable-conformance-c7ff485c68d2

@QuinceyMorris: Thank you for that ... I began to suspect that this was the case after more experimentation.

The next part of the question would be how to get that vector from a JSON reply.

Currently, I am using PHP to query a database, generating the result array, then using json_encode to create a JSON string. The json_encode creates the JSON style object for the CGPoint ... any ideas on how to create the vector style?

Or am I going to have to manually create the JSON string rather than rely on standardised implementation across all of my REST API?

Thank you in advance,

DSC.david

It depends a bit on the scale of the problem.

One solution would be just to write the manual decoding for types like Circle that contain a CGPoint. The synthesized code is almost trivial to re-create manually, so it's just a question of source code size.

Or, you could try to finagle the types like Circle like this:

struct MyPointStruct: Decodable {
     let x: CGFloat
     let y: CGFloat
}
struct Circle: Decodable {
     private var _center: MyPointStruct
     var center: CGPoint {
          get { return CGPoint (x: _center.x, y: _center.y) }
          set { _center = MyPointStruct (x: newValue.x, y: newValue.y) }
     }
}

Or perhaps slightly more cleanly, if you have lot of point-containing structs:

struct MyPointStruct: Decodable {
     var x: CGFloat
     var y: CGFloat
     var point: CGPoint {
          get { return CGPoint (x: x, y: y) }
          set { x = newValue.x; y = newValue.y }
     }
}
struct Circle: Decodable {
     private var _center: MyPointStruct
     var center: CGPoint {
          get { return _center.point }
          set { _center.point = newValue }
     }
}

That way, you don't have to do anything at the PHP end, or write any decoding code.

Oh, I forgot: you'd also have to declare the coding keys explicitly to get the JSON dictionary key to be "center" rather than "_center" (or whatever you choose as the private name).

I was trying to keep it all nice and "clean" so that I could avoid creating my own structs if possible.

I solved the problem by writing a decoder for the situation and left it at that.

Thank you very much for your help.

DSC.david