objective c - Special API to launch an app from my application

Question

I had asked a question here but the answer guide me to open a new topic. Shortly, i want to launch a free app on Appstore from my application but the app i want to launch has no URL Scheme. The comments on my other question say using some special APIs like SBSLaunchApplicationWithIdentifier or classes like UIDocumentInteractionController make it possible. Can anyone please help me how to launch an application from my appication. Thanks in advance

Answer 1

Let me first say that this method is jailbreak only! It uses private API's that Apple can stop supporting at any time in a future version!

Let's get to it, this method uses the [UIApplication launchApplicationWithIdentifier:suspended:] private method:

[[UIApplication sharedApplication] launchApplicationWithIdentifier:@"com.apple.Preferences" suspended:NO];

From what I've tested calling this method from an application not running as root is useless, apparently SpringBoard (or LaunchServices) only allow root applications to launch other applications using this method.

So, first you need to jailbreak your iPhone, then you need to get your application running as root.

To get your app running as root you need to place it in /Applications/YourApp.app instead of the usual /User/Applications/UUID/YourApp.app.

You can install OpenSSH using Cydia and use SSH to access your phone's shell.

Then, after having your app in the right place you need to set permissions, for example:

I would use the same ones as Cydia:

chown -R root:wheel /Applications/YourApp.app

Next, a little trick. The binary will need the setuid bit:

chmod 4755 /Applications/YourApp.app/YourApp

And for the last step, SpringBoard doesn't open apps with the setuid bit, but it opens a script (which can open another app)! Just change the name of the binary to something like YourApp_:

mv /Applications/YourApp.app/YourApp /Applications/YourApp.app/YourApp_

And create a new file named YourApp in your app folder with the following script:

#!/bin/bash
CrrDir=$(dirname "$0")
exec "${CrrDir}"/YourApp_

Now, just respring (there's an app for that in Cydia) and you're ready to go.

Sorry if this seems hard, it isn't, I don't remember where I learned it, but it was a long time ago. This method works fine in all iOS versions and I've just tested it with iOS 5.1.

Again, YOUR APP WILL NOT BE APPROVED BY APPLE IF YOU DO THIS.