将PFQuery的结果用作UIPageViewController的数据源

Question

I'm trying to create a UIPageViewController that allows the user to scroll through full screen renderings of data, which is stored in a Parse Database.

I started with XCode 6's page based application template, and have not changed anything in the DataViewController or the RootViewController.

In the initializer for the Model Controller, I added these lines of code:

var pageData:NSArray = []

private func generateQuery() -> PFQuery? {
        let query = PFQuery(className:"Posts")
        query.orderByDescending("createdAt")
        return query
}
override init() {
        super.init()
        if let query = generateQuery(){
            query.findObjectsInBackgroundWithBlock(){
                (objects,error) in
                if error != nil{
                    println("ERROR")
                }
                else{
                   self.pageData = objects! as NSArray

                    }
                }

            }
    }

And when I compile and run I always get "found nil while unwrapping optional value"

I've tried a bunch of different permutations of NSArray, [AnyObject], [PFObject], etc. I assume it has something to do with making an asynchronous query in the initializer. Is there any way to do this, or should I try something else?

Answer 1

Maybe it's just a typo, but:

query.findObjectsInBackgroundWithBlock(){ ... }

Should be :

query.findObjectsInBackgroundWithBlock({ ... })