Swift Compiler Error when accessing array - Exit code 254 - swift

Question

I am quite new to swift and got a pretty weird compiler error:
Command
/Applications/Xcode6-Beta5.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swiftc
failed with exit code 254
The Error occours when I ad the following lines to my code:
var response = HoopsClient.instance().collections["posts"]
response = response["_id"]
when I remove the second line everything compiles fine. I don't get it ^^
edit: The reason is probably that "response" is of type "AnyObject" according to the compiler... but shouldn't that be detected by xcode or give me a runtime error instead of this compiler error?

Answer 1

Try casting response as the type you're expecting. From what you're trying to do, instance().collections I would assume that it should return some type of dictionary.
var response = HoopsClient.instance().collections["posts"] as NSDictionary
That way, response now can handle subscripts so you could now (in theory) do:
response = response["_id"]
However
The error you get is regarding bad access to an array. This makes me think that instance().collections actually returns an array of some sort, containing Post objects.
Arrays in Swift can only handle Integer subscripts. If you want to access the information of a Post in the array, you can do something like this:
for post: Post in response {
println(post._id)
}
I know this is a long shot, but hope it helps.

Answer 2

Swift tends to throw error when it cant infer the type of an object, what you could probably do is add a conditional cast as follows
Im assuming that HoopsClient.instance().collections["posts"] is either a Dictionary or an Array
var response = HoopsClient.instance().collections["posts"]
if response is NSArray {
let item = response.objectAtIndex(0)
let reponseId: Post = item
}
if response is NSDictionary {
let item = response.objectForKet("_id")
let reponseId: Post = item
}
Any way, in my experience you should try to cast your variables when assigning from types that return AnyObject, xcode doesn't handle very well type inferring and when it's unable to infer the type the interface starts to throw error, like text editor uncoloring the code.