Shouldn't wrapped optionals always print with the keyword 'Optional'? - swift

Question

Code
func downloadimages (URL: NSURL) {
let request = NSMutableURLRequest ( URL: URL)
request.HTTPMethod = "GET"
let task = NSURLSession.sharedSession().dataTaskWithRequest(request) { (data, response, error ) in
guard error == nil else {
print("we have an error from Server")
return
}
var JSONData: AnyObject!
do {
JSONData = try NSJSONSerialization.JSONObjectWithData(data!, options: .AllowFragments) /* as? [String:AnyObject?] */
} catch {
print (" We had a Parsing issue '\(data)'")
return
}
print(JSONData)// Doesn't print 'Optional' word?????
print(JSONData!)
if let something = JSONData!["photos"]{
print (something!)
print(something) // This prints the word 'Optional as well'
}
Output
//printed unwrapped--NOT GOOD! -- I didn't unwrap it with '!'
{
photos = {
page = 1;
pages = 622374;
perpage = 1;
photo = (
{
farm = 8;
id = 27765969370;
isfamily = 0;
isfriend = 0;
ispublic = 1;
owner = "8262787#N07";
secret = 6daeee7d68;
server = 7233;
title = "Stars, Planets and Lightning Bugs";
}
);
total = 622374;
};
stat = ok;
}
// unwrapped printed--Good!
{
photos = {
page = 1;
pages = 622374;
perpage = 1;
photo = (
{
farm = 8;
id = 27765969370;
isfamily = 0;
isfriend = 0;
ispublic = 1;
owner = "8262787#N07";
secret = 6daeee7d68;
server = 7233;
title = "Stars, Planets and Lightning Bugs";
}
);
total = 622374;
};
stat = ok;
}
//Unwrapped printed--Good
{
page = 1;
pages = 622374;
perpage = 1;
photo = (
{
farm = 8;
id = 27765969370;
isfamily = 0;
isfriend = 0;
ispublic = 1;
owner = "8262787#N07";
secret = 6daeee7d68;
server = 7233;
title = "Stars, Planets and Lightning Bugs";
}
);
total = 622374;
}
//wrapped and prints as optional--Good!
Optional({
page = 1;
pages = 622374;
perpage = 1;
photo = (
{
farm = 8;
id = 27765969370;
isfamily = 0;
isfriend = 0;
ispublic = 1;
owner = "8262787#N07";
secret = 6daeee7d68;
server = 7233;
title = "Stars, Planets and Lightning Bugs";
}
);
total = 622374;
})
My confusion is, if JSONData is an optional then why does it print as non-optional without ! and if it isn't an optional then why doesn't it give any error as Can not force unwrap value of non-optional type?. Since unwrapping a non-optional is error-ful!
My guess is that I am not understanding what my JSONData's type really is...

Answer 1

My guess is that I am not understanding what my JSONData's type really is...
I believe that is the point.
You've declared JSONData as AnyObject!, which is also known as ImplicitlyUnwrappedOptional<AnyObject>.
So, in your code print(JSONData), the value of JSONData is implicitly unwrapped.
And check the type of something in the Quick Help pane of your Xcode. It should be displayed as AnyObject?, aka Optional<AnyObject>.
One bad thing is that when implicit unwrapping occurs it doesn't get well-documented. You may need to know more about ImplicitlyUnwrappedOptional, before knowing exactly when that happens.