Reading in a JSON File Using Swift

I'm really struggling with trying to read a JSON file into Swift so I can play around with it. I've spent the best part of 2 days re-searching and trying different methods but no luck as of yet so I have signed up to StackOverFlow to see if anyone can point me in the right direction.....

My JSON file is called test.json and contains the following:

{
"person":[
{
"name": "Bob",
"age": "16",
"employed": "No"
},
{
"name": "Vinny",
"age": "56",
"employed": "Yes"
}
]
}

The file is stored in the documents directly and I access it using the following code:

let file = "test.json"
let dirs : String[] = NSSearchPathForDirectoriesInDomains(
NSSearchpathDirectory.DocumentDirectory,
NSSearchPathDomainMask.AllDomainMask,
true) as String[]

if (dirs != nil) {
let directories: String[] = dirs
let dir = directories[0]
let path = dir.stringByAppendingPathComponent(file)
}

var jsonData = NSData(contentsOfFile:path, options: nil, error: nil)
println("jsonData \(jsonData)" // This prints what looks to be JSON encoded data.

var jsonDict = NSJSONSerialization.JSONObjectWithData(jsonData, options: nil, error: nil) as? NSDictionary

println("jsonDict \(jsonDict)") - This prints nil.....

If anyone can just give me a push in the right direction on how I can de-serialize the JSON file and put it in an accessible Swift object I will be eternally grateful!

Kind Regards,

Krivvenz.

This worked great with me

func readjson(fileName: String) -> NSData{

let path = NSBundle.mainBundle().pathForResource(fileName, ofType: "json")
let jsonData = NSData(contentsOfMappedFile: path!)

return jsonData!
}

I'm providing another answer because none of the ones here are geared toward loading the resource from the test bundle. If you are consuming a remote service that puts out JSON and want to unit test parsing the results without hitting the actual service, you take one or more responses and put them into files in the Tests folder in your project.

func testCanReadTestJSONFile() {
let path = NSBundle(forClass: ForecastIOAdapterTests.self).pathForResource("ForecastIOSample", ofType: "json")
if let jsonData = NSData(contentsOfFile:path!) {
let json = JSON(data: jsonData)
if let currentTemperature = json["currently"]["temperature"].double {
println("json: \(json)")
XCTAssertGreaterThan(currentTemperature, 0)
}
}
}

This also uses [SwiftyJSON](

[To see links please register here]

) but the core logic of getting the test bundle and loading the file is the answer to the question.

Here is my solution using <a href="https://github.com/SwiftyJSON/SwiftyJSON">SwiftyJSON</a>

if let path : String = NSBundle.mainBundle().pathForResource("filename", ofType: "json") {
if let data = NSData(contentsOfFile: path) {

let json = JSON(data: data)

}
}

Based on [Abhishek's answer][1], for iOS 8 this would be:

let masterDataUrl: NSURL = NSBundle.mainBundle().URLForResource("masterdata", withExtension: "json")!
let jsonData: NSData = NSData(contentsOfURL: masterDataUrl)!
let jsonResult: NSDictionary = NSJSONSerialization.JSONObjectWithData(jsonData, options: nil, error: nil) as! NSDictionary
var persons : NSArray = jsonResult["person"] as! NSArray

[1]:

[To see links please register here]

"Abhishek's answer"

Swift 2.1 answer (based on Abhishek's) :

if let path = NSBundle.mainBundle().pathForResource("test", ofType: "json") {
do {
let jsonData = try NSData(contentsOfFile: path, options: NSDataReadingOptions.DataReadingMappedIfSafe)
do {
let jsonResult: NSDictionary = try NSJSONSerialization.JSONObjectWithData(jsonData, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary
if let people : [NSDictionary] = jsonResult["person"] as? [NSDictionary] {
for person: NSDictionary in people {
for (name,value) in person {
print("\(name) , \(value)")
}
}
}
} catch {}
} catch {}
}

I’ve used below code to **fetch JSON** from FAQ-data.json file present in project directory .

I’m implementing in Xcode 7.3 using Swift.

func fetchJSONContent() {
if let path = NSBundle.mainBundle().pathForResource("FAQ-data", ofType: "json") {

if let jsonData = NSData(contentsOfFile: path) {
do {
if let jsonResult: NSDictionary = try NSJSONSerialization.JSONObjectWithData(jsonData, options: NSJSONReadingOptions.MutableContainers) as? NSDictionary {

if let responseParameter : NSDictionary = jsonResult["responseParameter"] as? NSDictionary {

if let response : NSArray = responseParameter["FAQ"] as? NSArray {
responseFAQ = response
print("response FAQ : \(response)")
}
}
}
}
catch { print("Error while parsing: \(error)") }
}
}
}

override func viewWillAppear(animated: Bool) {
fetchFAQContent()
}

**Structure of JSON file :**

{
"status": "00",
"msg": "FAQ List ",
"responseParameter": {
"FAQ": [
{
"question": “Question No.1 here”,
"answer": “Answer goes here”,
"id": 1
},
{
"question": “Question No.2 here”,
"answer": “Answer goes here”,
"id": 2
}
. . .
]
}
}

I might also recommend Ray Wenderlich's [Swift JSON Tutorial](

[To see links please register here]

) (which also covers the awesome SwiftyJSON alternative, [Gloss](

[To see links please register here]

)). An excerpt (which granted, by itself, does not fully answer the poster, but the added value of this answer is the link, so no -1's for that, please):


>In Objective-C, parsing and deserializing JSON is fairly straightforward:

NSArray *json = [NSJSONSerialization JSONObjectWithData:JSONData
options:kNilOptions error:nil];
NSString *age = json[0][@"person"][@"age"];
NSLog(@"Dani's age is %@", age);

>In Swift, parsing and deserializing JSON is a little more tedious due to Swift optionals and type-safety [but as] part of Swift 2.0 the `guard` statement was introduced to help get rid of nested `if` statements:

var json: Array!
do {
json = try NSJSONSerialization.JSONObjectWithData(JSONData, options: NSJSONReadingOptions()) as? Array
} catch {
print(error)
}

guard let item = json[0] as? [String: AnyObject],
let person = item["person"] as? [String: AnyObject],
let age = person["age"] as? Int else {
return;
}
print("Dani's age is \(age)")

Of course, in XCode 8.x, you just double-tap the space bar and say "Hey, Siri, please deserialize this JSON for me in Swift 3.0 with space/tab-indents."

Updated names for Swift 3.0

Based on [Abhishek's answer][Abhishek] and [Druva's answer][Druva]

func loadJson(forFilename fileName: String) -> NSDictionary? {

if let url = Bundle.main.url(forResource: fileName, withExtension: "json") {
if let data = NSData(contentsOf: url) {
do {
let dictionary = try JSONSerialization.jsonObject(with: data as Data, options: .allowFragments) as? NSDictionary

return dictionary
} catch {
print("Error!! Unable to parse \(fileName).json")
}
}
print("Error!! Unable to load \(fileName).json")
}

return nil
}


[Abhishek]:

[To see links please register here]

[Druva]:

[To see links please register here]

> Swift 3.0, Xcode 8, iOS 10

if let path = Bundle.main.url(forResource: "person", withExtension: "json") {

do {
let jsonData = try Data(contentsOf: path, options: .mappedIfSafe)
do {
if let jsonResult = try JSONSerialization.jsonObject(with: jsonData, options: JSONSerialization.ReadingOptions(rawValue: 0)) as? NSDictionary {
if let personArray = jsonResult.value(forKey: "person") as? NSArray {
for (_, element) in personArray.enumerated() {
if let element = element as? NSDictionary {
let name = element.value(forKey: "name") as! String
let age = element.value(forKey: "age") as! String
let employed = element.value(forKey: "employed") as! String
print("Name: \(name), age: \(age), employed: \(employed)")
}
}
}
}
} catch let error as NSError {
print("Error: \(error)")
}
} catch let error as NSError {
print("Error: \(error)")
}
}

***Output:***

Name: Bob, age: 16, employed: No
Name: Vinny, age: 56, employed: Yes