dataTaskWithURL sometimes no return - swift

Question

I have a very simple http request which will return a JSON data. Here is my code:
let query = NSString(format: "http://glosbe.com/gapi/translate?from=eng&dest=eng&format=json&phrase=test",src, dest, phrase )
let url = NSURL(string: query)
let task = NSURLSession.sharedSession().dataTaskWithURL(url) {(data, response, error) in
if let httpRes = response as? NSHTTPURLResponse {
println("status code=",httpRes.statusCode)
if httpRes.statusCode == 200 {
println(NSString(data: data, encoding: NSUTF8StringEncoding))
// parse data
let phrase = Phrase.parse(data)
println(phrase.description)
}
}
}
task.resume()
Sometimes the completionHandler isn't called at all. I suspect it's the problem of the server. But when I input the same url into my browser and tried a dozens times. There was no problem at all. The data was returned everything when I refresh the browser.
Is there anything wrong in my code? Thanks

Answer 1

The code works OK for me. I suggest you can make this change to your code (an else clause):
if let httpRes = response as? NSHTTPURLResponse {
println("status code=",httpRes.statusCode)
if httpRes.statusCode == 200 {
println(NSString(data: data, encoding: NSUTF8StringEncoding))
// parse data
let phrase = Phrase.parse(data)
println(phrase.description)
}
} else {
println("error \(error)") // print the error!
}
So you will have a better idea if anything goes wrong