how manipulate a NSDictionary generated by a json file in swift - swift

Question

I've a NSDictionary populated by a JSON file.
JSON file content (initially)
{
"length" : 0,
"locations" : []
}
I want add some elements in "locations". The elements have the below structure:
[
"name" : "some_name",
"lat" : "4.88889",
"long" : "5.456789",
"date" : "19/01/2015"
]
In next code I read de JSON File
let contentFile = NSData(contentsOfFile: pathToTheFile)
let jsonDict = NSJSONSerialization.JSONObjectWithData(contentFile!, options: nil, error: &writeError) as NSDictionary`
like you can see jsonDict contain the JSON's info but in a NSDictionary object.
At this point I can't add the elements mentioned before, I tried insert NSData, NSArray, Strings, and nothing results for me
After do this I want convert "final" NSDictionary in JSON again to save it in a file.
The "final" NSDictionary must be like this
{
"length" : 3,
"locations" : [
{
"name" : "some_name",
"lat" : "4.88889",
"long" : "5.456789",
"date" : "19/01/2015"
},
{
"name" : "some_name_2",
"lat" : "8.88889",
"long" : "9.456789",
"date" : "19/01/2015"
},
{
"name" : "some_name_3",
"lat" : "67.88889",
"long" : "5.456789",
"date" : "19/01/2015"
}
]
}
"length" control the index for new element
I have no more ideas to do this. thanks in advance

Answer 1

If you want to be able to modify the dictionary, you can make it mutable:
let jsonDict = NSJSONSerialization.JSONObjectWithData(contentFile!, options: .MutableContainers, error: &writeError) as NSMutableDictionary
The resulting NSMutableDictionary can be modified. For example:
let originalJSON = "{\"length\" : 0,\"locations\" : []}"
let data = originalJSON.dataUsingEncoding(NSUTF8StringEncoding)
var parseError: NSError?
let locationDictionary = NSJSONSerialization.JSONObjectWithData(data!, options: .MutableContainers, error: &parseError) as NSMutableDictionary
locationDictionary["length"] = 1 // change the `length` value
let location1 = [ // create dictionary that we'll insert
"name" : "some_name",
"lat" : "4.88889",
"long" : "5.456789",
"date" : "19/01/2015"
]
if let locations = locationDictionary["locations"] as? NSMutableArray {
locations.addObject(location1) // add the location to the array of locations
}
If you now constructed JSON from the updated locationDictionary, it would look like:
{
"length" : 1,
"locations" : [
{
"long" : "5.456789",
"lat" : "4.88889",
"date" : "19/01/2015",
"name" : "some_name"
}
]
}