The way in which Apple has approached the mobile space is by creating a separate, specified OS for mobile users. iOS was at first designed from the ground up specifically for touch, with no legacy software or functionality on either the mobile phone or tablet form factors. The third-party apps that Apple eventually did start to serve as a platform were also designed from the ground up specifically for touch. The only connection that iOS had to the PC during much of its short lifespan was for the purpose of syncing/backup but that link was broken when Apple launched iCloud.
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