Set to go on sale worldwide on April 24, Apple has been busy working behind-the-scenes to ensure that a batch of pre-existing apps are fine-tuned and fully compatible with its star wearable.

Only a select few companies have been granted the privilege to start work on its Apple Watch apps early, and regular developers will have to patiently wait for a later date before they can submit apps for approval for the tech giant's first ever wearable.

Credible companies that have been able to get their apps ready for the April 24 launch include Twitter, WeChat, Evernote and Dark Sky amongst others.

According to sources, the famously secretive Cupertino tech pioneer only allowed the developers to use a simulation platform – and not the physical Apple Watch – in its preparation, which provided a lot of inconvenience for the whole process.

Discover everything you need to know about the Apple Watch here.