GKRuleSystem-example.swift

GKRuleSystem-example.swift

// Being online asserts the online navigation option.
// And retracts the offline option.
self.add(GKRule(blockPredicate: { ruleSystem -> Bool in
  return Reachability.isOnline == true
}, action: { ruleSystem in
  log.verbose("Rule 1: User is online")
  ruleSystem.assertFact("navigableRoute")
  ruleSystem.retractFact("offlineNavigableRoute")
}))

// In the view controller
let isOnlineNavigable: Bool = self
  .ruleSystem?
  .grade(forFact: "navigableRoute") == 1

// There is also AND and OR relations for different facts
let grade = self.maximumGrade(forFacts: [
  "someFact",
  "anotherFact",
  "yetAnotherFactoid"
])

let grade = self.minimumGrade(forFacts: [
  "someFact",
  "anotherFact"
])