Understanding and Implementing Custom URL Schemes in iOS

Introduction

When developing mobile apps, it’s common to want users to be able to share custom URLs with others. This can be useful for a variety of purposes, such as sharing a link to your app’s homepage or inviting friends to download the app. However, by default, iOS will not recognize custom URL schemes and will instead display them in the app’s browser, which defeats the purpose.

In this article, we’ll explore how to implement custom URL schemes in iOS, including the necessary steps for development, testing, and deployment.

What are Custom URL Schemes?

A custom URL scheme is a unique string of characters that identifies an app and specifies how it should handle incoming URLs. When a user clicks on a link containing a custom URL scheme, the app will be launched if it’s installed on their device, or the URL will be opened in the default browser.

Why Do We Need Custom URL Schemes?

There are several reasons why you might want to use custom URL schemes:

Share links: By implementing a custom URL scheme, you can share a link with others that will automatically launch your app when clicked.
Integrate with other apps: Some other apps may support your custom URL scheme. For example, if you have a Twitter app that uses a custom URL scheme, users can click on the link and it will open in your app.
Prevent sharing in browsers: As mentioned earlier, iOS won’t recognize custom URL schemes by default. By implementing a custom URL scheme, you can prevent links from being shared in browsers.

The Required Steps for Custom URL Schemes

To implement a custom URL scheme, you’ll need to follow these steps:

Create the .entitlements file:
- Open your project’s Entitlements.plist file.
- Add the following string under the URL Types section:

{ “CFBundleURLSchemes” = (“com.example.app”) }

    Replace `"com.example.app"` with a unique string that identifies your app and custom URL scheme.
2.  **Register the URL scheme**:
    *   Open your app's `Info.plist` file.
    *   Add the following code to the `URL Schemes` section:
        ```
{
"URL Schemes" = ("com.example.app")
}

Replace `"com.example.app"` with a unique string that identifies your app and custom URL scheme.

Handle incoming URLs:
- In your app’s delegate, implement the application:handleOpenWithOptions:forURL: method to handle incoming URLs:

- (BOOL)application:(UIApplication *)application open options:(NSDictionary<NSExtensionAttributesKey, id> *)options URL:(NSURL *)url sourceAppIdentifier:(NSString *)sourceAppIdentifier annotation:(id)annotation {
    // Handle the incoming URL here

    return YES;
}

Test your custom URL scheme:
- Open the Xcode Organizer window by selecting Window -> Organizer from the Xcode menu.
- In the Organizer window, select your app and click on the Distribute App Over Air button to create a .ipa file.
- Share the .ipa file with others using an email or messaging service.
- Have them download and install the app on their device.
- Open Safari (or another browser) and navigate to a URL that uses your custom URL scheme:

https://example.com?scheme=com.example.app&data=Hello%2C+World!

Clicking on this link should launch your app.

Additional Considerations

Security:
- When implementing a custom URL scheme, make sure to handle sensitive data securely. For example, you may want to use HTTPS to encrypt the data transmitted between your server and the client.
Compatibility:
- Make sure that all devices running your app will support your custom URL scheme. You can check this by looking at Apple’s supported hardware on their website.

Conclusion

Implementing a custom URL scheme in iOS allows you to share links with others that will automatically launch your app when clicked. By following the steps outlined above, you can create a custom URL scheme for your app and take advantage of its benefits.

By understanding how custom URL schemes work, developers can create more seamless user experiences and integrate their apps better with other services. Whether it’s sharing links or integrating with other apps, custom URL schemes are an essential tool in any iOS developer’s toolkit.

Last modified on 2025-02-12