Understanding How iOS Interfaces Work
Part of the iOS App Development For Dummies Cheat Sheet
Tap a button and something happens. It's amazing to the user, but it's hard work for you. Here are the points you have to consider about making your iOS interface work:
What does the user want to do?: As you start to design your app, at various points, you'll see that the user will have to take an action. Start making a list of what those actions are beginning with what the user wants to do. (For instance, cancel an operation, find the nearest dog-friendly park, and so forth.)
How does the user do it?: Does the action start with tapping a button? Moving a slider? Shaking the device? Typing something?
Can the user have second thoughts?: There's a robust and sophisticated undo manager available for your use. Do you need it?
What does the user need to know?: Do you have to keep the user informed as the action is progressing? Do you need a progress bar? Periodic messages?
Does the user need to know when it's done?: All software today is becoming less talkative. In many cases, you don't have to tell that user that something has been done either because the user can see that it's done or because the user trusts your app to provide a notification if something has failed.
Does the action involve other objects?: Calculating 2 + 2 doesn't require anything else, but calculating Contents of field A + Contents of field B requires that you can get to the fields and find their values before you perform the operation.
How will the user know how to do it?: Ideally, the tool (button, slider, and so on) is right there when the user might need to use it. In other cases, it pops up in an alert or popover. Sometimes, the user may need to go to a help screen to even know that the action is possible.
Does the user need to know that it has been done?: Some actions can only be done once; others may be unnecessary. If a list has been alphabetized, realphabetizing may or may not be allowed (if the data has changed, it generally is allowed).