Parse JSON causes swift dynamic cast failed - php

Question

The goal is to display a result of json_encode result from php into swift as a label. I have referenced to many tutorials and practices of parsing json with swift, but I still cant understand the issue.
I referenced to an example that uses date.jsontest.com and that works fine.
In my project, I have parsed this simple JSON object to start:
[{"username":"user"}]
Here is the swift code:
override func viewDidLoad() {
super.viewDidLoad()
// 1
//let urlAsString = "http://date.jsontest.com"
let urlAsString = "http://(ip address)/service.php"
let url = NSURL(string: urlAsString)!
let urlSession = NSURLSession.sharedSession()
// 2
let jsonQuery = urlSession.dataTaskWithURL(url, completionHandler: { data, response, error -> Void in
if (error != nil) {
println(error.localizedDescription)
}
var err: NSError?
// 3
var jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &err) as NSDictionary
if (err != nil) {
println("JSON Error \(err!.localizedDescription)")
}
// 4
//let jsonDate: String! = jsonResult["date"] as NSString
//let jsonId = jsonResult["id"] as NSString
//let jsonTime: String! = jsonResult["time"] as NSString
let jsonUser: String! = jsonResult[0] as NSString
dispatch_async(dispatch_get_main_queue(), {
//self.dateLabel.text = jsonId
//self.timeLabel.text = jsonUser
self.dateLabel.text = jsonUser
})
})
// 5
jsonQuery.resume()
//searchItunesFor("JQ Software")
//startConnection()
// Do any additional setup after loading the view, typically from a nib.
}
The code runs fine when I use http://date.jsontest.com as the string along with jsonDate and jsonTime.
I tried to understand the debugger in Xcode, but as a new user to Swift, its hard to understand what the issue is. All I could root out is that there is an issue with how my JSON is formatted.
Any tips are greatly appreciated, thanks.
EDIT:
Here is the code http://(ip address)/service.php that gives me the JSON
<?php
//connect to MySQL
// Create connection
$con=mysqli_connect($hostname,$username,$password,$database);
// Check connection
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
// This SQL statement selects ALL from the table 'Locations'
$sql = "SELECT username FROM members WHERE id = 1";
// Check if there are results
if ($result = mysqli_query($con, $sql))
{
// If so, then create a results array and a temporary one
// to hold the data
$resultArray = array();
$tempArray = array();
// Loop through each row in the result set
while($row = $result->fetch_object())
{
// Add each row into our results array
$tempArray = $row;
array_push($resultArray, $tempArray);
}
// Finally, encode the array to JSON and output the results
echo json_encode($resultArray);
}
// Close connections
mysqli_close($con);
?>