Designing for Adverse Network and Temperature Conditions.md

Designing for Adverse Network and Temperature Conditions

@ WWDC 19

Real-World Network Conditions

• Reduced responsiveness
• Perceived app freezing
• Functional problems

Qualities of Good Tests

• Repeatable
• Deterministic
• Low variance
• Representative

Testing Under Network Conditiions

• Conditioning the network infrastructure
  • Custom routers
  • Can be prohibitively complex

Designing for Adverse Network Conditions

• Use Optimistic DNS and TLS 1.3
• Use HTTP/2
• Set reasonable timeouts
• Avoid reachability checks
• Consider differences between testing conditions and the real world
• Use your app with different Link conditions
• Be aware of functional and performance degradation
• Include 3G Network Link in test runs
• Optimize towards progressing app behavior

Defensive Design

• Reduce your app's energy impact and contribution to excessive thermal states
• Implement progressive optimizations under elevated thermal states
• Listen to ProcessInfo.ThermalState notifications

Designing for Adverse Thermal Conditions

• Register for ProcessInfo.thermalStateDidChangeNotification
• Use the ProcessInfo.ThermalState cases to react to thermal state changes
• Switch off background and unneeded functionaliity when thermal state is elevated

NotificationCenter.default.addObserver(self, selector: #selector(reactToThermalStateChange(_:)), name: ProcessInfo.thermalStateDidChangeNotification, object: nil)

@objc fnc reactToThermalStateChange(_ notification: Notification) {
  thermalState = ProcessInfo.processInfo.thermalState
}

var thermalState = ProcessInfo.ThermalState.nominal {
  didSet {
    switch thermalState {
    case .nominal, .fair:
      configuration.userFaceTrackingEnabled = true
      configuration.frameSemantics = .personSegmentation
      sceneView.renderMotionBlur = true
    case .serious:
      configuration.userFaceTrackingEnabled = false
      configuration.frameSemantics = .init()
      sceneView.renderMotionBlur = true
    case .critical:
      configuration.userFaceTrackingEnabled = false
      configuration.frameSemantics = .init()
      sceneView.renderMotionBlur = false
    }
  }
}

Testing Under Temperature Conditions

• Doon't extrapolate behavior from nominal conditions
• Avoid running a dummy CPU load to warm the device
• Don't overlook the energy impact of your app

Summary

• Add test runs with adverse device conditions
• Look for progressions in your application behavior
• Activate different Network Links such as 3G
• Activate elevated temperature states such as the Serious state