How to save an array as a json file in Swift?

If you’re like me who doesn’t like to use a whole new third-party framework just for a trivial thing like this, here’s my solution in vanilla Swift. From creating a .json file in the Documents folder to writing JSON in to it.

let documentsDirectoryPathString = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true).first!
let documentsDirectoryPath = NSURL(string: documentsDirectoryPathString)!

let jsonFilePath = documentsDirectoryPath.URLByAppendingPathComponent("test.json")
let fileManager = NSFileManager.defaultManager()
var isDirectory: ObjCBool = false

// creating a .json file in the Documents folder
if !fileManager.fileExistsAtPath(jsonFilePath.absoluteString, isDirectory: &isDirectory) {
    let created = fileManager.createFileAtPath(jsonFilePath.absoluteString, contents: nil, attributes: nil)
    if created {
        print("File created ")
    } else {
        print("Couldn't create file for some reason")
    }
} else {
    print("File already exists")
}

// creating an array of test data
var numbers = [String]()
for var i = 0; i < 100; i++ {
    numbers.append("Test\(i)")
}

// creating JSON out of the above array
var jsonData: NSData!
do {
    jsonData = try NSJSONSerialization.dataWithJSONObject(numbers, options: NSJSONWritingOptions())
    let jsonString = String(data: jsonData, encoding: NSUTF8StringEncoding)
    print(jsonString)
} catch let error as NSError {
    print("Array to JSON conversion failed: \(error.localizedDescription)")
}

// Write that JSON to the file created earlier
let jsonFilePath = documentsDirectoryPath.URLByAppendingPathComponent("test.json")
do {
    let file = try NSFileHandle(forWritingToURL: jsonFilePath)
    file.writeData(jsonData)
    print("JSON data was written to teh file successfully!")
} catch let error as NSError {
    print("Couldn't write to file: \(error.localizedDescription)")
}