Building an iOS App Interface
A lot goes on behind the scenes in an app, but users don't see that. What they see is your interface. Here are some points to remember as you build your user interface (UI):
Study Apple's Human Interface Guidelines, native apps, and sample: Even with a free membership, you can find plenty of information on the Apple Developer site. Get to know the layout of what's there. Look critically at the native apps on your iOS devices and study the documentation.
Study the UI history: Particularly if you're new to iOS, look at Apple's documentation for the prior version of iOS as well as media reports that you can find online. (You may also go back a few versions.) What you're looking for is what's new in iOS 7 and what was new in iOS 6. Why were those changes made? Don't accidentally revert to a prior version that is now supplemented.
Know your user: The more you can clarify who you're designing for, the better your app will be. Some apps are designed for general use in the mass market, but others are highly specialized.
Think globally: If there's any chance at all that your app will need to be translated, study the localization information on the Apple Developer site so that you don't have to come back and redo things. It's easier to build in localization features and not use them than to have to add them in during the middle of development.
Find your look: What will make your app look like your app? In iOS 7, there's a concept of a tint color — one special color that you use for certain interface elements. Users quickly come to recognize that the tint color is for app controls. (On built-in native apps in iOS, it's often blue.) You don't have room for a logo on each screen.
Set up your Xcode project: Even if you're not yet coding, set up a project you can use to test things out. This is not going to be your app — you're going to toss it out after your experiments are done.
Think about performance: Things such as databases on the iOS device, websites or databases that access the Internet, use of location or other device features, and anything else that isn't just code need a bit of extra attention.
Think about security: Read up on security measures you must take, particularly if you're writing an app for kids.