It's not hard to find great lists of the best apps to load into your iPhone and iPad, if you want to load up on crowd favorites such as Facebook. Apps are the cornerstone of Apple's iOS platform. The ecosystem is what sets Apple's mobile platform apart from its rivals, and the highest-quality iPhone apps. Tap an icon, launch an app. But which apps should you launch? Out of the almost one million apps on the iPhone App Store which are the. The app, equally happy in portrait and landscape, is initially set up for vector-based sketching, with you scribbling freehand lines that can subsequently be tweaked and edited. The iPad app provides expanded view modes and split-screen support. The online bit works especially well, providing speedy access to a huge range of existing constructions that you can download and experiment. The app is a counting aid. The app also works with video — although results there are a mite more variable.