Launching Native Views in Ionic

We have covered the general process for passing data from our application to the native APIs and receiving data back. Another thing we can add to our bag of tricks is launching native views.

As you may know, the application that the user sees is generally our web code running inside of a Web View (which is a type of native view). However, we can also incorporate other native views into our application as well.

Whilst it is technically possible to sort of display a separate native view within our application (e.g. a native list that displays inside of our Ionic application) - this relies on a lot of hacky style code and I don’t generally recommend it. You should just focus on making your user interface nice using web code inside of the web view.

However, it is quite feasible to launch a separate native view on top of our web view. This could work especially well in situations where you want the user to go to the view and then come back from it - kind of like when you launch a pop up modal. Maybe the user launches it, selects something, and then goes back to the previous page. Or, maybe they launch a view to view some 3D model animation, and then close that view when they are done.

In this lesson, we are going to walk through how to display a native iOS list on top of our web view. The idea is that we will be able to call this code:

ListView.present({
  items: ['My', 'item', 'array'],
});

To launch a view like this:

Lists with massive amounts of data can be one of the tricky things to pull off in an Ionic application. One of the biggest performance bottlenecks for a web-based application is having to deal with a large DOM (i.e. having lots of elements/nodes in your application). Naturally, if you want to display a list with hundreds or thousands of elements, you are going to have a large DOM.

Ionic does provide the ion-virtual-scroll component which helps a great deal with performance in this scenario since it recycles just a few DOM elements rather than having hundreds or thousands in the DOM at the same time, but there are a lot of limitations that come along with ion-virtual-scroll which can make it difficult to use. Generally, I would recommend using ion-infinite-scroll when dealing with large lists in Ionic so that you don’t need to load the entire list at once, but still, you might want to just have the entire massive list displayed all at once in some cases.

If ion-virtual-scroll does not suit your needs, nor does ion-infinite-scroll, then this is the case where perhaps using a native list view might suit your needs.

NOTE: Make sure to run the ionic cap sync or npx cap sync commands before attempting to open the native projects.

Create the Plugin

Although we will be doing something a bit different here, we can still follow the same basic steps for creating a plugin. First, you will need to open Xcode:

npx cap open ios

or

ionic cap open ios

Within XCode, you will need to expand App on the left, and then select the App target within that:

You can then right click it to create a new file - you should choose a Swift file and name it something like ListViewPlugin.swift. You could then add the following code to the file:

import Foundation
import Capacitor
@objc(ListViewPlugin)
public class ListViewPlugin: CAPPlugin {
    @objc func present(_ call: CAPPluginCall) {
        let items = call.getArray("items", String.self) ?? [String]()
        let listView = TableViewController()
        listView.items = items
        DispatchQueue.main.async {
            self.bridge?.viewController?.present(listView, animated: true)
        }
    }
}
class TableViewController: UITableViewController {
    var items: [String] = [String]()
    override func viewDidLoad(){
        super.viewDidLoad()
        tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cell")
    }
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return items.count
    }
    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
        cell.textLabel?.text = items[indexPath.row]
        return cell
    }
}