Creating the iOS List Screenlet's Interactor

Recall that Interactors implement your Screenlet’s actions. In list Screenlets, loading entities is usually the only action a user can take. The Interactor class of a list Screenlet that implements fluent pagination must extend the BaseListPageLoadInteractor class. Your Interactor class must also contain any properties the Screenlet needs, and an initializer that sets them. This initializer also needs arguments for the following properties, which it passes to the superclass initializer:

• screenlet: A BaseListScreenlet reference. This ensures the Interactor always has a Screenlet reference.
• page: The page number to retrieve.
• computeRowCount: Whether to call the Connector’s doAddRowCountServiceCall method.

For example, Bookmark List Screenlet’s Interactor class contains the same groupId and folderId properties as the Connector, and an initializer that sets them. This initializer also passes the screenlet, page, and computeRowCount arguments to the superclass initializer:

public class BookmarkListPageLoadInteractor : BaseListPageLoadInteractor {

    private let groupId: Int64
    private let folderId: Int64

    init(screenlet: BaseListScreenlet,
        page: Int,
        computeRowCount: Bool,
        groupId: Int64,
        folderId: Int64) {

            self.groupId = (groupId != 0) ? groupId : LiferayServerContext.groupId
            self.folderId = folderId

            super.init(screenlet: screenlet, page: page, computeRowCount: computeRowCount)
    }
    ...

The Interactor class must also initiate the server request by instantiating the Connector, and convert the results into model objects. Override the createListPageConnector method to create and return an instance of your Connector. This method must first get a reference to the Screenlet via the screenlet property. When calling the Connector’s initializer, use screenlet.firstRowForPage to convert the page number (page) to the page’s start and end indices. You must also pass the initializer any other properties it needs, like groupId. For example, BookmarkListPageLoadInteractor’s createListPageConnector method does this to create a BookmarkListPageLiferayConnector instance:

public override func createListPageConnector() -> PaginationLiferayConnector {
    let screenlet = self.screenlet as! BaseListScreenlet

    return BookmarkListPageLiferayConnector(
        startRow: screenlet.firstRowForPage(self.page),
        endRow: screenlet.firstRowForPage(self.page + 1),
        computeRowCount: self.computeRowCount,
        groupId: groupId,
        folderId: folderId)
}

Next, override the convertResult method to convert each [String:AnyObject] result into a model object. The Screenlet calls this method once for each entity retrieved from the server. For example, BookmarkListPageLoadInteractor’s convertResult method converts the [String:AnyObject] result into a Bookmark object:

override public func convertResult(_ serverResult: [String:AnyObject]) -> AnyObject {
    return Bookmark(attributes: serverResult)
}

You may also want to support offline mode in your Interactor. To do so, the Interactor must override the cacheKey method to return a cache key unique to your Screenlet. For example, BookmarkListPageLoadInteractor’s cacheKey method returns a cache key that includes the Screenlet’s groupId and folderId settings:

override public func cacheKey(_ op: PaginationLiferayConnector) -> String {
    return "\(groupId)-\(folderId)"
}

Great! Next, you’ll create your Screenlet’s delegate.

« Creating the iOS List Screenlet's ConnectorCreating the iOS List Screenlet's Delegate »