SwiftJsonUtilities

A Swift library to make JSON parsing in Swift language as simple as possible.

Swift is strict with type checking, making parsing JSON objects difficult. Here's a blog post written by David.

This project aims to remove most of the complexity of JSON handling in Swift by using DSL style syntax.

How To Use It

Installation

Add SwiftJsonUtilities.swift to your project.

Example

Sample JSON to parse:

{
    "blogs": {
        "blog": [
            {
                "id": 73,
                "name": "Bloxus test",
                "needspassword": true,
                "url": "http://remote.bloxus.com/"
            },
            {
                "id": 74,
                "name": "Manila Test",
                "needspassword": false,
                "url": "http://flickrtest1.userland.com/"
            }
        ]
    },
    "stat": "ok"
}

Define a Blog class to represent a blog post:

class Blog {
    var name : String?
    var id : Int?
    var needsPassword : Bool?
    var url : String?
}

Actual parsing code. The parse() method accepts object types of NSData, String, NSDictionary or NSArray.

JsonUtilities.parse(json) { p in
    
    var stat = p.string("stat")
    var title = p.string("title")
    
    var blogList = [Blog]()
    
    p.dict("blogs") {
        p.array("blog") {
            
            let blog           = Blog()
            blog.id            = p.integer("id")
            blog.name          = p.string("name")
            blog.needsPassword = p.bool("needspassword")
            blog.url           = p.string("url")

            blogList.append(blog)
            
        }
    }
}

Custom datatype parsing can be supported by defining a custom method on extension of class JsonUtilities.Parser. The below code snippet define a method url() to parse NSURL object. The method can be called inside a parsing context.

extension JsonUtilities.Parser {
  func url(key: String) -> NSURL? {
      if let urlString = string(key) {
          return NSURL(string: urlString)
      }
      return nil
  }
}

// Usage:
JsonUtilities.parse(json) { p in
   
   // Parse an url object
   blog.url = p.url("url")
}

We can define a custom method to parse Blog objects:

extension JsonUtilities.Parser {
    func blog() -> Blog? {
        let blog = Blog()
        blog.id             = self.integer("id")
        blog.name           = self.string("name")
        blog.needsPassword  = self.bool("needspassword")
        blog.url            = self.url("url")
        return blog
    }
}


// Usage:
JsonUtilities.parse(TestData.json) { p in
    
    var blogList = [Blog]()
    
    p.dict("blogs") {
        p.array("blog") {
            
            if let blog = p.blog() {
                blogList.append(blog)
            }
            
        }
    }
}

Alternate Solutions

• [json-swift] by David (https://github.com/owensd/json-swift/)
• [SwiftyJSON] by lingoer (https://github.com/lingoer/SwiftyJSON)

License

This project is under MIT License, please feel free to contribute and use it

Simon Pang