Your user expects a good experience. In this chapter, you will see how to enhance your PWA with splash screens, app shortcuts, and how sessions work.
There are many enhancements that can improve the conversion and usage of your PWA.
App shortcuts #
App shortcuts is a static list of deep links to your PWA, they are written in your manifest. Web App Manifest spec. It lets you define a list of shortcuts to different parts or features in your PWA, they accelerate navigation to frequently accessed sections.
App shortcuts are available on most desktop operating systems and Android with WebAPK, and they appear in a contextual menu on the app's icon in the home screen, dock, or taskbar, as in the following image:
To access this menu, users have to right-click or long-press on the PWA's icon.
Shortcuts are defined in the
shortcuts member of the manifest. It takes an array of members with the following properties:
name : The text that will be shown to the user, typically in a context menu.
start_url. : The URL the PWA should load when the user starts it from this shortcut. It should be a URL within your PWA scope, and it should deep-link to the feature the
short_name (Optional) A shorter name used when there is not enough room to display the full value of the
description : (Optional) A description of what this shortcut will do
icons : (Optional) An array of icon objects with
sizes, and optional
purpose fields, describing what images should represent the shortcut
You should treat App shortcuts as a best-effort ability. That means that you can't rely on these shortcuts to appear consistently, and even if they appear, you don't know how many shortcuts will appear or if the platform will ignore the icons as its at the discretion of the browsers. A full discussion per platform is out of scope but below you have an idea of how it works on Android and desktop. The best way to deal with this uncertainty is to order the items by priority.
The following code sample defines different app shortcuts you can try if you install the app on Android with Chrome or on desktop with Edge or Chrome.
iOS and iPadOS #
When publishing PWAs, there are some enhancements that can improve the experience for users on Safari on iOS/iPadOS.
Splash screens #
As seen in the Web App Manifest chapter, Android creates splash screens automatically based on the manifest's values. That's not the case for iOS and iPadOS. In these devices, you should define the splash screens in the HTML as static images using
These images are known as startup images on Apple devices and they use the
rel property with
apple-touch-startup-image value, as in:
<link rel="apple-touch-startup-image" href="ios-startup.png">
The challenge is that the startup image must have the exact window size that your PWA will have on opening. So, different iOS and iPadOS devices will need different images. More situations need to be covered on the iPad, such as landscape/portrait openings and rendering the PWA in multitask mode (such as 1/3,1/2, or 2/3 of the screen).
You can check an updated list of iOS and iPadOS screen sizes at the Apple Human Interface Guidelines
Different versions of the launch image can be set with a media query inside the
<link rel="apple-touch-startup-image" href="ios-startup.png"
<link rel="apple-touch-startup-image" href="ios-startup-landscape.png">
Design patterns for iOS startup images #
Defining startup images is hard work, so we have a couple of tools for automated generation and configuration:
- Static generation integrates with your build system, creates all the PNG static images and gives you the HTML code with
<link>elements to inject into your document. PWA Asset Generator is an example of such a tool.
<link>injected elements based on the current device's type and screen size. You can use an in-memory canvas, render the image and convert it into a
data:URI with a PNG file. ThePWA Compat library is an easy-to-use client-side library that does this by cloning the Android's typical launch screen.
Detecting a PWA on Apple mobile platforms #
While you should use Progressive Enhancement and feature detection in your PWA, there may be some edge cases where we need to know if the user is in a PWA on Apple mobile platforms, such as when you want to offer installation instructions or add links to platform-specific apps that are iOS-only.
To avoid reading the user agent string, check the
standalone property of the
navigator object. This is a non-standard property, and it's only available on the WebKit engine on iOS and iPadOS.
undefinedit means the user is not on an iPadOS or iOS device.
falseit means the user opened the PWA in the browser and is using it there.
trueit means the user opened the PWA from the home screen and is getting the standalone PWA experience.
Fullscreen support #
On Safari on iOS and iPads, only
display: standalone is supported as a display mode for your PWA's icon. While
display: fullscreen is not supported as on Android devices, it's possible to use a non-standard meta-tag to make your PWA enter fullscreen mode.
In the next image, you can see at the left a default standalone design with a theme color, and at the right a PWA with a fullscreen iOS mode that lets you render content behind the status bar.
If you add the following tag in your HTML your PWA on iOS and iPadOS will enter full-screen mode, but it is different from Android.
<meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
In this mode, the device's status bar (the top where you see the clock, battery level, and notification icons) is still visible but rendered on top of your content with a transparent background.
When using this mode, be careful with your design because the operating system will always render the icons in white, so you should always contrast your backgrounds for the top of the screen with light content. Also, it's important to use CSS environment variables to render content in the safe area, as seen in App Design Chapter.
Installation reliability #
Safari on iOS and iPadOS before 15.4 only loads the manifest file from the network when the user opens the share sheet -using the share icon within the browser- and not when the page loads. Therefore, Safari doesn't check if your website is a PWA until that moment, which can lead to situations where the manifest can't be loaded or takes too much time, and Safari ignores it.
When Safari can't load the manifest on time, pressing "Add to Home Screen" places an icon on the home screen, but does not provide an app experience; it will merely be a shortcut to a Safari tab.