How to convert NSObject class object into JSON in Swift?

问题

I have

var  contacts : [ContactsModel] = []

and

class ContactsModel: NSObject
{
   var contactEmail : String?
   var contactName : String?
   var contactNumber : String?
   var recordId : Int32?
   var modifiedDate : String?
}

Now in contacts I'm having 6 values like

Now i want to convert contacts into JSON how can i ?

I tried

  var jsonData: NSData?
        do
        {
            jsonData = try NSJSONSerialization.dataWithJSONObject(contacts, options:NSJSONWritingOptions.PrettyPrinted)
        } catch
        {
            jsonData = nil
        }
  let jsonDataLength = "\(jsonData!.length)"

But it crashes the app.

My issue is with manually converting in to a Dictionary one by one very time consuming it takes more than 5 minutes for 6000 records, So instead of that i want to convert directly model into JSON and send to server.

回答1:

Your custom object can't be converted to JSON directly. NSJSONSerialization Class Reference says:

An object that may be converted to JSON must have the following properties:

The top level object is an NSArray or NSDictionary.

All objects are instances of NSString, NSNumber, NSArray, NSDictionary, or NSNull.

All dictionary keys are instances of NSString.

Numbers are not NaN or infinity.

You might convert your object to a Dictionary manually or use some libraries like SwiftyJSON, JSONModel or Mantle.

Edit: Currently, with swift 4.0+, you can use Codable protocol to easily convert your objects to JSON. It's a native solution, no third party library needed. See Using JSON with Custom Types document from Apple.

回答2:

If you just want a simple Swift object to JSON static function without any inheritance or dependencies to NSObject or NS-types directly. Check out:

https://github.com/peheje/JsonSerializerSwift

Full disclaimer. I made it. Simple use:

//Arrange your model classes
class Object {
  var id: Int = 182371823
  }
class Animal: Object {
  var weight: Double = 2.5
  var age: Int = 2
  var name: String? = "An animal"
  }
class Cat: Animal {
  var fur: Bool = true
}

let m = Cat()

//Act
let json = JSONSerializer.toJson(m)

Currently supports standard types, optional standard types, arrays, arrays of nullables standard types, array of custom classes, inheritance, composition of custom objects.

回答3:

You can use NSJSONSerialization for array when array contains only JSON encodable values (string, number, dictionary, array, nil)

first you need to create the JSON object then you can use it (your code is crashing because contact is not a JSON object!)

you can refere below link

https://developer.apple.com/library/ios/documentation/Foundation/Reference/NSJSONSerialization_Class/#//apple_ref/doc/uid/TP40010946-CH1-SW9

来源：https://stackoverflow.com/questions/34171791/how-to-convert-nsobject-class-object-into-json-in-swift

标签

json

swift

nsobject

nsjsonserialization