User defined runtime attributes are the hidden gem of Xcode’s Interface Builder. Available since Xcode 4 and iOS 5, they provide the ability to configure properties of a view that you would otherwise be unable to configure in Interface Builder.
A crash (or system crash) in computing is an event in which a computer or a program (such as a software application or an operating system) ceases to function properly, often exiting after encountering errors. The program responsible may appear to freeze or hang until a crash reporting service documents details of the crash. If the program is a critical part of the operating system kernel, the entire computer may crash, often resulting in a fatal system error. […]