How to turn off Core Data Write-Ahead logging in Swift using options dictionary?

Question

How do I turn off the SQLite Write ahead logging (WAL) in Core Data using Apples new programming language Swift?

In ObjC I used to pass in the key value pair @\"jour

Answer 1

Swift dictionaries are strongly typed by default, but you can define the types your dictionary should accept.

var options = Dictionary()
options[NSMigratePersistentStoresAutomaticallyOption] = true
options[NSInferMappingModelAutomaticallyOption] = true
options["journal_mode"] = "DELETE"

[storeCoordinator addPersistentStoreWithType:NSSQLiteStoreType
                               configuration:nil
                                         URL:[self databaseURL]
                                     options:opitons
                                       error:&error]

If you weren't sure what type of dictionary the function was expecting, just take a look at the function declaration :

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

It describes exactly the type of dictionary it expects -- Dictionary.

In fact, any dictionary that is bridged from Objective-C will be typed this way. From the Apple Docs:

Swift also automatically bridges between the Dictionary type and the NSDictionary class. When you bridge from an NSDictionary object to a Swift dictionary, the resulting dictionary is of type [NSObject: AnyObject].

You can bridge any NSDictionary object to a Swift dictionary because all Objective-C objects are AnyObject compatible. Recall that an object is AnyObject compatible if it is an instance of an Objective-C or Swift class, or if it can be bridged to one. All NSDictionary objects can be bridged to Swift dictionaries, so the Swift compiler replaces the NSDictionary class with [NSObject: AnyObject] when it imports Objective-C APIs.

Likewise, when you use a Swift class or protocol in Objective-C code, the importer remaps Objective-C compatible Swift dictionaries as NSDictionary objects.