Sometimes, especially when dealing with offsets in UIScrollViews or other, we need to clamp a certain undefined range of numbers into another defined array of numbers.
Unused images can be cleaned up using several free tools like LSUnusedResources and FengNiao. Learn how to use those tools and keep your projects clean.
In an average day of UIKit programming, you might subclass UIView, add some child views, override -layoutSubviews, and repeat. But on weird days, when you need to do weird things, you start to look at those other methods on UIView that you can override.
The best way to debug applications during development is to run them in simulator and the best way to run simulator is right next to Xcode in fullscreen.