Problems parsing json String to objects in Swift - json

Question

I googled a lot, pretty much copied code i found online from tutorials to simply parse a json String in Swift to useable objects.
Code:
func parseJson(json: String) -> [AnyObject] {
let data = json.dataUsingEncoding(NSUTF8StringEncoding)
do {
if let array = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers) as? [AnyObject] {
return array
}
}
catch {
// Error hanndling here
}
return [AnyObject]()
}
Json String im trying to parse:
"response":{"loggedIn":false,"message":"Some errormessage here"}}
What happens:
The program won't jump into the if let array = ... It stops there since it can't parse the string to json (or AnyObject) and will simply go to return AnyObject.
Why does this happen and how do i fix it?

Answer 1

Adjust your code a little to allow for better debugging:
func parseJson(json: String) -> [AnyObject] {
let data = json.dataUsingEncoding(NSUTF8StringEncoding)
do {
let parsed = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers)
if let array = parsed as? [AnyObject] {
return array
}
}
catch {
print(error)
}
return [AnyObject]()
}
Two changes there:
Printing any error caught.
Doing JSONObjectWithData and the as? conversion in two separate steps.
Pasting this in a playground quickly reveals an error being caught: "JSON text did not start with array or object and option to allow fragments not set." Your JSON fragment is missing the opening {.
Once that problem is fixed, you’ll see that parsed gets set, but the subsequent if let array = parsed as? [AnyObject] falls through. That’s because your top-level element is a dictionary, not an array, so casting to [AnyObject] fails.