Launch an app from within another (iPhone)

Question

Is it possible to launch any arbitrary iPhone application from within another app?, For example in my application if I want the user to push a button an

Answer 1

To achieve this we need to add few line of Code in both App

App A: Which you want to open from another App. (Source)

App B: From App B you want to open App A (Destination)

Code for App A

Add few tags into the Plist of App A Open Plist Source of App A and Past below XML

<key>CFBundleURLTypes</key>
<array>
    <dict>
        <key>CFBundleURLName</key>
        <string>com.TestApp</string>
        <key>CFBundleURLSchemes</key>
        <array>
            <string>testApp.linking</string>
        </array>
    </dict>
</array>

In App delegate of App A - Get Callback here

- (BOOL)application:(UIApplication *)application openURL:(NSURL *)url
  sourceApplication:(NSString *)sourceApplication annotation:(id)annotation
{
// You we get the call back here when App B will try to Open 
// sourceApplication will have the bundle ID of the App B
// [url query] will provide you the whole URL 
// [url query] with the help of this you can also pass the value from App B and get that value here 
}

Now coming to App B code -

If you just want to open App A without any input parameter

-(IBAction)openApp_A:(id)sender{

    if(![[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"testApp.linking://?"]]){
         UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"App is not available!" message:nil delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
            [alert show];

        }
}

If you want to pass parameter from App B to App A then use below Code

-(IBAction)openApp_A:(id)sender{
    if(![[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"testApp.linking://?userName=abe&registered=1&Password=123abc"]]){
         UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"App is not available!" message:nil delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
            [alert show];

        }
}

Note: You can also open App with just type testApp.linking://? on safari browser

Answer 2

You can only launch apps that have registered a URL scheme. Then just like you open the SMS app by using sms:, you'll be able to open the app using their URL scheme.

There is a very good example available in the docs called LaunchMe which demonstrates this.

LaunchMe sample code as of 6th Nov 2017.