URL Scheme - How to Gather URL Scheme

Dear Hacker News citizen,

I am currently creating a launcher app for iPhone, similar to Launch Center by App Cubby http://appcubby.com/launch-center/.

I am having trouble launching few apps on my iPhone with the launcher app that I am developing.

Is there any way to make sure my launcher app with launch every possible apps?

I asked my friend and he said that I must gather all of the URL schemes of all existing iPhone apps, is that true?

I do understand that I will need to gather URL schemes so my launcher app will detect what apps the user have on his iPhone.

It would be very helpful if I can get an idea how to gather URL schemes of iPhone apps!

Is there an existing API of URL schemes?

Again, thank you very much for your time and kindness :)!