I prefer not to use the '_' prefix because Apple does use it consistently. By avoiding the prefix I then have greater confidence that my ivars do not collide with Apple's when I extend a cocoa touch class. Since we do not have access to the base class' source this is really the only way I know of to avoid accidental reuse of existing private ivars.
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Method names beginning with “_”, a single underscore character, are reserved for use by Apple.
