[swift-evolution] [Review] SE-0167: Swift Encoders

piotr gorzelany piotr.gorzelany at gmail.com
Mon Apr 10 04:36:43 CDT 2017

This is a really great proposal. As an iOS developer I work with JSON
almost every day since most mobile apps communicate with a backend through
JSON messages. It's good to see that better JSON support is coming to
Foundation so we don't have to rely on third party libraries.

That being said, there is one thing I don't like which is that the JSON
encoding function returns Data and the decoding function takes Data.

It would be really great if the Foundation team could introduce a dedicated
type of JSON.
There are several advantages of working with a dedicated type.
- The underlying data is always valid JSON
- You can extend this type in the future with helper methods for
manipulating JSON
- It makes it explicit what you are dealing with

A good analogy is the URL type. You could represent an URL with a String or
Data type, but by introducing a dedicated type you have the full advantages
mentioned above. Data on the other hand is like a generic container which
you cannot easily extend with URL or JSON specific methods.

Having a dedicated JSON type is also one of the reasons third party
libraries like SwiftyJSON are so popular. It makes it super easy to
manipulate JSON structures. And sometimes developers like would like to
manipulate JSON directly.

If the proposal would pass in the current form, I would still use
SwiftyJSON for manipulating JSON which I would rather avoid and have this
all sorted on the Foundation level.

Just my two cents from the perspective of an iOS developer. JSON handling
is really important to us so I hope you make it great!


Hello Swift community,

The review of SE-0167 "Swift Encoders" begins now and runs through
April 12, 2017. The proposal is available here:
Note that this proposal is closely related to (and dependent on)
SE-0166: Swift Archival & Serialization
Please read and review that proposal as well!

Reviews are an important part of the Swift evolution process. All
reviews should be sent to the swift-evolution mailing list at
or, if you would like to keep your feedback private, directly to the
review manager. When replying, please try to keep the proposal link at
the top of the message:

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