Rules help creativity form
The Human Interface Guidelines gives the feeling of a technical document, shocking,  since it’s coming from Apple, but its okay because the rules were created to help you understand the technical characteristics of the platform, therefore design for it better. Acknowledge that rules give you support to work from and that, knowing those limits, can help you be more creative.
Elements are imperative
The ‘iOS UI Elements Usage Guidelines’ section provides a very practical breakdown of how and when to use the absolute core building blocks of interface, such as the navigation bar, table lists and button. You need to know and admire the default interface in order to create sincere great ones.
Consider the screen
Designing for the screens on iOS mobile devices is a different situation to designing for the web, as they’re very bright and very reflective. They can be used both indoors and outdoors – and are usually covered in fingerprints. So test it many times on the actual screen during the design process.
Create custom icons
Icons embody a user’s first experience of an ipad app, so you should think about how they work at different sizes. For example, the larger version of the Contacts icon looks as an address book with a ring binding and letters down the side; the smaller version instead of being reduced down in size, its just a suggestion of the larger icon.
Explore Orientation
Research shows that often when users rotate a device, they’re prepared to immerse themselves more deeply in that topic. Therefore you want too use consider switching to a landscape orientation as a trigger for extra features, such as video a clip. Consider the idea that most users use more than one finger to interact with the app
Gestures, not clicks
The way a user interacts with the mobile app should be a fundamental part of how you design your user interface. It is best to focus on gestures as opposed to clicks, and anytime a user is made to click, the “hit region” should be large enough for their fingers, or even thumbs.  The sides of screens are a sweet spot for those users who are comfortable using their thumbs as they hold their device in their palm.
The invisible grid
The Apple Human Interface Guidelines state that no interactive element, such as a button, should be less than 44 points wide or high. Those dimensions are a standard for a grid that relies on 44 points.
Keep focused
Focus on the primary task; Offer one or two robust features as opposed to trying to offer several features of a lesser standard. Users typically spend short a,punts of time using one app because they are interrupted, keep things simple and focused.
Make it stretchable
Stretchable views are similar to nine-slice scaling in Fireworks. For example, if you’re creating a button with rounded edges that you want to stay the same shape whatever size it is, you need to make sure it has stretchable views so that iOS can stretch the middle part of the button as much as it wants without warping the image.
Get the basics right
When developing for iOS, you need to read the Human Interface Guidlines, consider it Apple’s bible. It provides solid advice, primarily found in the ‘Human Interface Principles’ section, such as keeping all your interfaces contend and giving users helpful and informative feedback as they wait for tasks to complete or pages to load.
Here at helium creative we take all of these points and more into consideration when developing any app for iOS. When we read the HIG we feel like it is preaching to the converted and want to print it out, frame it and put it on the wall!