Local Persistent Store is a Key Value store for iOS. It's written in Swift but fully compatable with Objective-C.

Open the store and prepare it for writing:

NSError *error = nil;
if (![[LOPStore defaultStore] openAndReturnError:&error]) {
  // Super good error handling
}

Write a value:

NSString *name = @"Loper";
[[LOPStore defaultStore] setObject:name forKey:@"project_name" inScope:nil];

Reading a value:

NSString *name = [[LOPStore defaultStore] stringForKey:@"project_name" inScope:nil];

If the value isn't found nil will be returned.

Scopes allow you to manage a group of keys. E.G.

[[LOPStore defaultStore] setObject@"[email protected]" forKey:@"email" inScope:@"logged_in"];

// User logs out

NSError *error = nil;
if (![[LOPStore defaultStore] deleteScope:@"logged_in" error:&error]) {
  // Super good error handling
}

NSString *email = [[LOPStore defaultStore] stringForKey:@"email" inScope:@"logged_in"];
// email == nil

This will delete all values with the logged_in scope.

If nil is passed to scope then [LOPStore scope] will be used. Keys MUST be unique for a scope. So setting foo : nil a second time will replace the original value in the store. But setting foo : bar will insert a new value into the bar scope and keep the default scope value intact.

Because Loper is backed by a SQLite database occasionally you'll need to run cleanup to repack the database file if your keys are volatile.

NSError *error = nil;
if (![[LOPStore defaultStore] cleanupAndReturnError:&error]) {
  // Super good error handling
}

This operation can be slow and should occure on a background thread. All reads & writes to the store will be blocked until this operation is completed.