We like to have a consistent coding style in the WordPress for iOS app, and to help us achieve this we’ve drafted a style guide outlining preferred code formatting, some preferred language idioms.
It’s a good idea to check the style guide from time to time as we update it to account for new improvements in the Objective-C language or in the iOS SDK.
Apple maintains an iOS Human Interface Guidelines document that “describes the guidelines and principles that help you design a superlative user interface and user experience for your iOS app.” Any new UI elements you create when contributing to the app should follow Apple’s guide.
We’ve set up a page that outlines the design philosophy for all WordPress Mobile Apps here, make sure you read through it as well.