This document discusses different revenue models for iOS apps, including paid downloads, sponsorship, in-app purchases, and advertising. It notes that paid downloads work best for games and utilities, sponsorship is best for niche apps but not scalable, in-app purchases require loyal repeat usage, and advertising can drive more revenue than paid but requires a large installed base. The document also provides data showing that eCPMs (cost per thousand impressions) for iOS apps are significantly higher than for Android apps in both North America and Europe. It encourages developing iOS apps and monetizing through the advertising network InMobi.