fairbanksdan / ios-engineer-exercise

Eventboard iOS Engineer Exercise

Architecture Exercise

This exercise is designed to test your ability to architect code that accepts input from multiple sources and do the correct thing with that input.

The Application

The app simulates a visual alarm going off under certain conditions. If you build and run the app, you'll see five grey circles along the bottom of the screen. These are your alarm lights. When the alarm is on, they'll be red, when the alarm is off, they'll be grey.

Near the top of the screen, you'll see a slider labeled "Danger Level." Once the app works, the user should be able to drag this slider. Once the slider goes above a certain threshold, the alarm will turn on.

The app also shows a "Settings" button. Tapping the "Settings" button presents a settings screen. This screen has a slider for "Alarm Threshold" and a switch for "Alarm Enabled." Once the app works, the "Alarm Threshold" slider will control the threshold that the "Danger Level" slider is tested against to determine whether or not to activate the alarm. The "Alarm Enabled" switch will control whether or not the alarm can be activated at all, regardless of the "Alarm Threshold" and "Danger Level" values.

Unfortunately, at present the "Danger Level" slider, the "Alarm Threshold" slider, and the "Alarm Enabled" switch don't do anything. For the exercise, you need to make them all work.

Requirements

• Danger Level
  • Should be a floating point value that ranges from 0.0 to 1.0, inclusive.
  • Should default to 0.5.
  • Should not be saved, the value should reset to 0.5 on every app launch.
  • Should be bound to the "Danger Level" slider on the main screen.
• Alarm Threshold
  • Should be a floating point value that ranges from 0.0 to 1.0, inclusive.
  • Should default to 0.9.
  • Should be saved and persist between app launches.
  • Should be bound to the "Alarm Threshold" slider on the Settings screen.
• Alarm Enabled
  • Should be a boolean.
  • Should default to true.
  • Should be saved and persist between app launches.
  • Should be bound to the "Alarm Enabled" switch on the Settings screen.
• Alarm
  • Should activate whenever all of the following are true:
    • Danger Level >= Alarm Threshold.
    • Alarm Enabled == true.
    • The app is in the foreground.
  • If any of those conditions become false, the alarm should deactivate.

Implementation

Essentially all of the UI layer is already implemented for you. There's a Storyboard and UIViewController subclasses, and those subclasses have already had outlets and actions wired up. Your responsibility is to write the code that manages the application's internal state.

The alarm is activated and deactivated via functions declared in Alarm.h. For the purposes of the exercise, you should pretend that Alarm.h/.m are not editable, as though they came from an external third-party library which controls a light or a horn. The exercise will ultimately test if you call activateAlarm and deactivateAlarm in the correct situations.

AlarmViewController is already fully implemented, and reflects the state of the alarm. You shouldn't need to modify this class to fulfill the requirements of the exercise. Since it visually reflects the state of the alarm, it will also help you when developing.

There is no existing code to manage the Danger Level, Alarm Threshold, or Alarm Enabled values, nor code that calls activateAlarm or deactivateAlarm. You are free to create any new classes that you feel are appropriate to fulfill the app's requirements. You can also freely edit any source files that you haven't otherwise been prohibited from editing.