Rendering Web Pages in Your iOS App

The Rendering Web Content tutorial shows you how to display web content from a Liferay Portal site in your iOS app. Displaying content is great, but what if you want to display an entire page? No problem! Web Screenlet lets you display any web page. You can even customize the page by injecting local or remote JavaScript and CSS files. When combined with Liferay Portal’s server-side customization features (e.g., Application Display Templates), Web Screenlet gives you almost limitless possibilities for displaying web pages in your iOS apps.

In this tutorial, you’ll learn how to use Web Screenlet to display web pages in your iOS app.

Inserting Web Screenlet in Your App

Inserting Web Screenlet in your app is the same as inserting any Screenlet in your app:

  1. In Interface Builder, insert a new view (UIView) in a new view controller. This new view should be nested under the view controller’s existing view.

  2. With the new view selected, open the Identity inspector and set the view’s Custom Class to WebScreenlet.

  3. Set any constraints that you want for the Screenlet in the scene.

The exact steps for configuring Web Screenlet are unique to Web Screenlet. First, you’ll conform your view controller to Web Screenlet’s delegate protocol.

Conforming to Web Screenlet’s Delegate Protocol

To use any Screenlet, you must conform the class of the view controller that contains it to the Screenlet’s delegate protocol. Web Screenlet’s delegate protocol is WebScreenletDelegate. Follow these steps to conform your view controller to WebScreenletDelegate:

  1. Import LiferayScreens and set your view controller to adopt the WebScreenletDelegate protocol:

    import UIKit
    import LiferayScreens
    
    class ViewController: UIViewController, WebScreenletDelegate {...
    
  2. Implement the WebScreenletDelegate method onWebLoad(_:url:). This method is called when the Screenlet loads the page successfully. How you implement it depends on what (if anything) you want to happen upon page load. Its arguments are the WebScreenlet instance and the page URL. This example prints a message to the console indicating that the page was loaded:

    func onWebLoad(_ screenlet: WebScreenlet, url: String) {
        // Called when the page is loaded
        print("\(url) was just loaded")
    }
    
  3. Implement the WebScreenletDelegate method screenlet(_:onError:). This method is called when an error occurs loading the page, and therefore includes the NSError object. This lets you log or print the error. For example, this implementation prints a message containing the error’s description:

    func screenlet(_ screenlet: WebScreenlet, onError error: NSError) {
        print("Failed to load the page: \(error.localizedDescription)")
    }
    
  4. Implement the WebScreenletDelegate method screenlet(_:onScriptMessageNamespace:onScriptMessage:). This method is called when the Screenlet’s WKWebView sends a message. This method’s arguments include the message’s namespace and the message. How you implement this method depends on what you want to happen when the message is sent. For example, you could perform a segue and include the message as the segue’s sender:

    func screenlet(_ screenlet: WebScreenlet,
        onScriptMessageNamespace namespace: String,
        onScriptMessage message: String) {
    
        performSegue(withIdentifier: "detail", sender: message)
    }
    
  5. Get a reference to the Web Screenlet on your storyboard by using Interface Builder to create an outlet to it in your view controller. It’s a best practice to name a Screenlet outlet after the Screenlet it references, or simply screenlet. Here’s an example Web Screenlet outlet:

    @IBOutlet weak var webScreenlet: WebScreenlet?
    
  6. In the view controller’s viewDidLoad() method, use the Web Screenlet reference you just created to set the view controller as the Screenlet’s delegate. To do this, add the following line of code just below the super.viewDidLoad() call:

    self.webScreenlet?.delegate = self
    

Next, you’ll use the same Web Screenlet reference to set the Screenlet’s parameters.

Setting Web Screenlet’s Parameters

Web Screenlet has WebScreenletConfiguration and WebScreenletConfigurationBuilder objects that supply the parameters the Screenlet needs to work. These parameters include the URL of the page to load and the location of any JavaScript or CSS files that customize the page. You’ll set most of these parameters via WebScreenletConfigurationBuilder’s methods.

To set Web Screenlet’s parameters, follow these steps in the viewDidLoad() method of a view controller that uses Web Screenlet:

  1. Use WebScreenletConfigurationBuilder(<url>), where <url> is the web page’s URL string, to create a WebScreenletConfigurationBuilder object. If the page requires Liferay Portal authentication, then the user must be logged in via Login Screenlet or a SessionContext method, and you must provide a relative URL to the WebScreenletConfigurationBuilder constructor. For example, if such a page’s full URL is http://your.liferay.instance/web/guest/blog, then the constructor’s argument is /web/guest/blog. For any other page that doesn’t require portal authentication, you must supply the full URL to the constructor.

  2. Call the WebScreenletConfigurationBuilder methods to set the parameters that you need.

  3. Call the WebScreenletConfigurationBuilder instance’s load() method, which returns a WebScreenletConfiguration object.

  4. Set the WebScreenletConfiguration object to the Web Screenlet instance’s configuration property.

  5. Call the Web Screenlet instance’s load() method.

Here’s an example snippet of these steps in the viewDidLoad() method of a view controller in which the Web Screenlet instance is webScreenlet, and the WebScreenletConfiguration object is webScreenletConfiguration:

override func viewDidLoad() {
    super.viewDidLoad()

    self.webScreenlet?.delegate = self

    let webScreenletConfiguration = 
        WebScreenletConfigurationBuilder(url: "/web/westeros-hybrid/companynews")
            .addCss(localFile: "blogs")
            .addJs(localFile: "blogs")
            .load()
    webScreenlet.configuration = webScreenletConfiguration
    webScreenlet.load()
}

The relative URL /web/westeros-hybrid/companynews supplied to the WebScreenletConfigurationBuilder constructor, and the lack of a set(webType: .other) call, indicates that this Web Screenlet instance loads a Liferay Portal page that requires authentication. The addCss and addJs calls add local CSS and JavaScript files, respectively. Both files are named blogs.

Great! Now you know how to use Web Screenlet in your iOS apps.

Web Screenlet for iOS

Using Web Screenlet with Cordova in Your iOS App

Using Screenlets in iOS Apps

Rendering Web Content in Your iOS App

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