Swift-如何检查现有的Core Data Store iOS

Question

I'm working on an app that should have a starting window that will have an intro and then either a "Get Started" button if no existing core data store is found, and then if a store is present - it should have a "Continue Session" and "Start Over" buttons. Only problem I don't think my code for checking for a store is working - I'm putting this in the ViewController's viewDidLoad function:

override func viewDidLoad() {
    super.viewDidLoad()
    let defaultStorePath = NSBundle.mainBundle().pathForResource("LearnUSStateCapitals", ofType: "sqlite")
    let fileManager = NSFileManager.defaultManager()
    if defaultStorePath == nil {
        println("can't find store")
        generateSCA()
    } else {
        println("store found...I think")
        continueButton.hidden = false
    }

So all I'm getting is "can't find store" - even after running the app a few times. I've navigated to \\Library\\Developer\\CoreSimulator\\Devices\\blahblah\\data\\Containers\\Data\\Application\\blahblah\\Documents and do see my "LearnUSStateCapitals.sqlite" file there created at the time I first ran the app as is...

The reason I'm using if defaultStorePath == nil is because when I try if fileManager.fileExistsAtPath(defaultStorePath!) I get unexpectedly found nil while unwrapping an Optional value - why is this nil maybe the real question... thanks for any help

Answer 1

The file you can see is in the Application Documents directory, which is different from the main bundle. You can get a URL for the application documents directory with:

let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
let appDocsURL : NSURL = urls[urls.count - 1] as NSURL
let defaultStoreURL = appDocsURL.URLByAppendingPathComponent("LearnUSStateCapitals.sqlite")

then use:

if !fileManager.fileExistsAtPath(defaultStoreURL.path!) {
    println("can't find store")
    generateSCA()
} else {
    println("store found...I think")
    continueButton.hidden = false
}