Optimize for 5G networks

Each generation leap results in increased opportunities for app developers to push the envelope and deliver previously unheard-of experiences in your app

Path to 5G

5G provides other advances beyond just more data at a faster rate:

• faster round-trip times between your app and your server - meaning faster and more synchronized transactions

• 5G’s ability to handle more devices concurrently - you can continue to deliver data-related services in your app, even in congested public environments

• …and more

Built-in intelligence

Today’s modern 5G cellular networks come primarily in two varieties, Non-Standalone (NSA) and Standalone (SA).

• Non-Standalone

  • built on the existing LTE core

  • can use both LTE and 5G links to schedule traffic

  • operates at frequencies below seven gigahertz

  • includes support for millimeter wave

• Standalone

  • built entirely on the new 5G core

  • operates at frequencies below seven gigahertz

  • includes support for millimeter wave

  • delivers improved latency performance over LTE

Thanks to Automatic Switch to 5G and Smart Data Mode, iOS takes performance, security, and power into consideration when choosing which connectivity to use - your app can focus on the user experience.

Practical guidance for developers

• ignore network type

• use high-level (Apple’s) frameworks to take full advantage of 5G

  • AVFoundation for Media

  • CallKit for VOIP

  • Network framework/Foundation’s URLSession

• tune your application for constrained and expensive paths

  • in most cases, these are automatically derived by the system based on the active cellular plan

  • the user can also affect these by altering the Data Mode settings on their device - there are three options:

    • Allow More Data on 5G - indicating an inexpensive path, similar to Wi-Fi

    • Standard mode - which is usually considered as expensive

    • Low Data Mode - which is considered constrained

The concept of expensive and constrained are surfaced as properties in all our high-level networking frameworks - the value of these properties should be your only consideration when determining the type of network services available for your app.

• URLSession’s allowsExpensiveNetworkAccess

private func fetchAsset(at fetchURL: URL, allowsExpensive: Bool) {
  var fetch = URLRequest(url: fetchURL,
                         cachePolicy: .reloadIgnoringLocalCacheData,
                         timeoutInterval: 60)
  fetch.allowsExpensiveNetworkAccess = allowsExpensive // 👈🏻
 
  // Fallback to low resolution fetch if network is expensive and unavailable
  URLSession.shared.dataTask(with: fetch) { [weak self] data, response, error in
    if let strongSelf = self,
      let error = error as? URLError,
      error.networkUnavailableReason == .expensive { // 👈🏻
        strongSelf.fetchAsset(at: strongSelf.lowResURLString, allowsExpensive: true)
    }
  }.resume()
}

if your application implements policy based on expensive, provide a way for users to influence that policy

• In Network.framework, you have another option to check for constrained, expensive, and inexpensive path:

func onConnectionStateChange(_ connection: NWConnection) {
  guard let path = connection.currentPath else { return } // insure we have a path

  if connection.state == .ready {
    // Update your data usage heuristics based on cost for this connection
    
    if path.isConstrained {
      // Reduced Data Usage
    } else if path.isExpensive {
      // Default Data Usage
    } else {
      // Unrestricted Data Usage
    }
  }
}

• AVFoundation:

  • AVURLAssetAllowsConstrainedNetworkAccessKey - Allows network requests to use the constrained interface

  • AVURLAssetAllowsExpensiveNetworkAccessKey - Allows network requests to use the expensive interface