Creating a Standalone Application to Launch Another on iPhone: Exploring Custom URL Schemes and App Store Guidelines

Introduction

As a developer, it’s not uncommon to encounter situations where you need to launch another application from within your own app. This can be useful for various purposes, such as bypassing certain steps or accessing additional features. In this article, we’ll explore the concept of custom URL schemes and their role in achieving this goal on iPhone.

Understanding Custom URL Schemes

A custom URL scheme is a way to associate a specific URL with an application. When a user clicks on a link that contains the associated URL scheme, the operating system will attempt to launch the associated application. This mechanism allows developers to create shortcuts or links that can open their app without using the standard “open” URL.

For example, if you have an app called MyApp and you want users to be able to launch it from a link, you would define a custom URL scheme for your app, such as myapp://. When a user clicks on a link that starts with myapp://, the iPhone will attempt to launch MyApp.

Defining a Custom URL Scheme

To define a custom URL scheme, you’ll need to create an Info.plist file in your Xcode project. This file contains metadata about your app, including its URL schemes.

<key>URL Types</key>
<array>
    <dict>
        <key>CFBundleURLSchemes</key>
        <array>
            <string>myapp</string>
        </array>
    </dict>
</array>

In this example, we’ve defined a single URL scheme called myapp.

Creating the Shortcut App

Now that we have our custom URL scheme defined, we can create a new app in Xcode that will act as a shortcut to launch our main application.

Step 1: Create a New Project

Create a new Xcode project and choose the “Single View App” template. Name this project ShortcutApp.

Step 2: Add the Main Application URL Scheme

Open the Info.plist file in ShortcutApp and add the following line to the CFBundleURLSchemes array:

<array>
    <string>myapp</string>
</array>

This tells the iPhone that our app will handle the custom URL scheme.

Step 3: Implement the Shortcut Logic

In the ViewController.swift file, add the following code to implement the shortcut logic:

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Get the launch URL from the URL bar
        guard let url = UIApplication.shared.application(_:launchOptions:forUrlRepresentation:) else { return }

        // Parse the URL and extract the scheme
        var components = URLComponents()
        components.scheme = "myapp"
        let urlString = components.string ?? ""

        // Launch the main application with the extracted scheme
        guard let mainAppUrl = URL(string: urlString) else { return }
        UIApplication.shared.open(mainAppUrl, options: [:], completionHandler: nil)
    }

}

This code retrieves the launch URL from the URL bar and parses it to extract the custom URL scheme. It then launches the main application with this scheme.

Handling the Shortcut Link

To handle the shortcut link, you’ll need to create a new view controller that will display the main application’s UI. Create a new Xcode project and choose the “Single View App” template. Name this project MainApp.

Step 1: Implement the Main Application URL Scheme

Open the Info.plist file in MainApp and add the following line to the CFBundleURLSchemes array:

<array>
    <string>myapp</string>
</array>

This tells the iPhone that our app will handle the custom URL scheme.

Step 2: Implement the View Controller

In the ViewController.swift file, add the following code to implement the view controller:

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Get the launch URL from the URL bar
        guard let url = UIApplication.shared.application(_:launchOptions:forUrlRepresentation:) else { return }

        // Parse the URL and extract the scheme
        var components = URLComponents()
        components.scheme = "myapp"
        let urlString = components.string ?? ""

        // Launch the main application with the extracted scheme
        guard let mainAppUrl = URL(string: urlString) else { return }
        UIApplication.shared.open(mainAppUrl, options: [:], completionHandler: nil)
    }

}

This code launches the main application with the custom URL scheme.

Apple App Store Guidelines

While creating a shortcut app to launch another app can be technically feasible, it’s essential to consider Apple’s app store guidelines. The App Store Review Guidelines explicitly state that “apps must meet certain quality and security standards,” which includes having a legitimate reason for using a custom URL scheme.

In this case, the shortcut app is essentially launching another app, which may not meet the guidelines. However, if you can demonstrate a legitimate reason for doing so (e.g., providing additional features or improving user experience), you may be able to get approval from Apple.

Conclusion

Creating a standalone application to launch another on iPhone involves defining a custom URL scheme and creating a shortcut app to handle this scheme. While this mechanism is technically feasible, it’s essential to consider Apple’s app store guidelines and ensure that your implementation meets the required standards.

By understanding how custom URL schemes work and implementing them correctly, you can create innovative solutions that enhance user experience without violating Apple’s guidelines.

Example Use Cases

Shortcut App with Custom UI: Create a shortcut app that displays a custom UI, allowing users to interact with the main application more intuitively.
Additional Features: Provide additional features or functionality in the shortcut app that are not available in the main application.
Improved User Experience: Improve the user experience by launching the main application directly from within the shortcut app.

Additional Resources

Last modified on 2025-03-26