Apple iOS UI and general design are considered one of the best due to it’s a simple and sleek design which is easy to use for anyone.
The main guidelines for Apple iOS development in the design are Accessibility, Internationalism, Marketing, Accessories.
Accessibility
Apple products come standard with award-winning accessibility features that let people experience everything the products have to offer. Products can be personalized by the customer to an extent and there’s a wide range of products suited to various people’s lifestyles. Applications should follow this with the application being available to everyone or most audiences, regardless of disability type or severity of impairment.
Internationalism
This somewhat links to accessibility, as apple products must, of course, be accessible to everyone meaning the design must work internationally. Taking various cultures into consideration when designing the format. Fonts and format must be easy to translate in other countries. Applications should have the option to change the language for their audience, what’s the point of an application if its only in one language?
Marketing
Apple has some iconic marketing, you can tell an advertisement is about Apple products due to its modern and sleek production. These adverts being appropriate to be shown on various media. So Obviously, your advertisement for your product should follow under similar guides as to be appropriate.
Accessories
If your product is not an application but rather a physical feature to an apple device, then there is also a guide for that. Usually discussing on the build of your product being similar to official apple accessories but more importantly safe for consumers to use.
Source guides:
https://developer.apple.com/videos/frameworks/accessibility
Hollie Hurwood's Game Design course work 