examples for blog

1.article.swift

func performPreflightCheck -> Bool {
  guard let fuelTank = self.fuelTank else { return false }
  guard fuelTank.fuel.type == .jetFuel else { return false }
  let destination = self.flightPlan.dest
  let origin = self.flightPlan.origin
  let distance = origin.distanceFrom(destination)

  let currentFuelLevel = fuelTank.level
  let currentBodyWeight = hardwareService.currentWeight
  let windSpeed = WeatherService.averageWindSpeed(forFlightPlan:flightPlan)
  let supportedTravelDistance = fuelTank.calculateSupportedTravelDistance(withFuelLevel:currentFuelLevel, bodyWeight:currentBodyWeight, windSpeed:windSpeed)

  guard (supportedTravelDistance - distance) > 1000 else { return false }
  guard (Date.now - fuelTank.lastMaintenanceTime < TWO_DAYS) else { return false }

  ...

  guard currentWeather = weatherService.currentWeather(onRoute:flightPlan.route)
  guard hardwareService.lowestWorkingTemp < currentWeather.lowestTemp { return false }
  guard hardwareService.highestWorkingTemp > currentWeather.highestTemp { return false }
  guard currentWeather.stormProbability < 0.002 { return false }

  guard destinationWeather = weatherService.weather(in:flightPlan.dest at:flightPlan.ETA)

  ...

  let engines = hardwareService.engines
  for engine in engines {
    guard (Date.now - engine.maintenanceTime < TWO_DAYS) else { return fasle }
    ...
  }

  ...

}