The ORKNavigableOrderedTask class adds conditional step navigation to the behavior inherited from the ORKOrderedTask class.

For implementing conditional task navigation, you must instantiate concrete subclasses of ORKStepNavigationRule and ORKSkipStepNavigationRule and attach them to trigger steps by using the setNavigationRule:forTriggerStepIdentifier: and setSkipNavigationRule:forStepIdentifier: methods.

For example, if you want to display a survey question only when the user answered Yes to a previous question you can use ORKPredicateStepNavigationRule; or if you want to define an arbitrary jump between two steps you can use ORKDirectStepNavigationRule. You can also optionally omit steps by using ORKPredicateSkipStepNavigationRule objects.

Note that each step in the task can have at most one attached navigation rule and one attached skip navigation rule.

Navigable ordered tasks support looping over previously visited steps. Note, however, that results for steps that are visited more than once will be ovewritten when you revisit the step on the loop. Thus, going over a loop will produce duplicate results within the task results for the steps that are seen more than once, but all the duplicate step results will point to the same result instance: the one corresponding to the last time you visited the step.

The same applies when navigating backwards over looped steps: only your last valid answer is shown every time you encounter a revisited step.