类型“NSPersistentStore”在swift中不符合协议“BooleanType”

Question

This code displays where my error is located:

do {
    //error showing at this line         
    if try coordinator!.addPersistentStoreWithType(NSSQLiteStoreType, configuration:nil, URL: url, options:nil) {
        coordinator = nil
        // Report any error we got.
        var dict = [String: AnyObject]()
        dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data"
        dict[NSLocalizedFailureReasonErrorKey] = failureReason
        dict[NSUnderlyingErrorKey] = error
        error = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
        NSLog("Unresolved error \(error), \(error!.userInfo)")
        abort()
    }
} catch {
    print(error)
}

Compiler gives this error: Type 'NSPersistentStore' does not conform to protocol 'BooleanType'

Why am I getting this error?

Answer 1

The function definition you're using:

func addPersistentStoreWithType(_ storeType: String, configuration configuration: String?, URL storeURL: NSURL?, options options: [NSObject : AnyObject]?) throws -> NSPersistentStore

so this is a function which can throw and which returns a persistent store.

Your code says if try coordinator!.addPers... , which is 'if the persistent store returned is true then...'. A persistent store isn't true (or false), so it isn't a boolean. You've written the code like a status is returned, but a (non-optional) object is returned (assuming the function doesn't throw).