How to call rest web service from swift - json

Question

I am trying to follow a tutorial - which failed and having found some code on stack over flow Make REST API call in Swift decided to try this approach instead. The following code is a copy and paste (I know!) with a change of URL yet I seem to be getting an error printed to the console rather than the JSON - the error being largely unhelpful - 0x0000000000000000
The JSON appears to print to the browser window so I am not fully sure what might be wrong with this approach? Please could someone provide some help as to why this might not be working?
Thanks
var url : String = "http://www.flickr.com/services/rest/?method=flickr.test.echo&format=json&api_key=d6e995dee02d313a28ed4b799a09b869"
var request : NSMutableURLRequest = NSMutableURLRequest()
request.URL = NSURL(string: url)
request.HTTPMethod = "GET"
NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) -> Void in
var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil
let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary
if (jsonResult != nil) {
println(jsonResult);
} else {
// couldn't load JSON, look at error
println(error);
}
})

Answer 1

The problem is that the call returns data in JSONP not JSON
Your code would work ok if tested with a correct JSON like http://ip.jsontest.com
To make it work with Flickr you have to modify it as follows:
var json_str:NSString = NSString(data: data, encoding: NSUTF8StringEncoding)
json_str = json_str.substringFromIndex(14)
json_str = json_str.substringToIndex(json_str.length-1)
let new_data:NSData = json_str.dataUsingEncoding(NSUTF8StringEncoding)!
var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil
let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(new_data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary
if (jsonResult != nil) {
println(jsonResult);
} else {
// couldn't load JSON, look at error
println(error);
}