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WWDC25 · 28 min · System Services

Filter and tunnel network traffic with NetworkExtension

Learn about the APIs in the NetworkExtension framework that give your app the power and flexibility to extend the system’s core networking features — like implementing network content filters, creating and managing VPN configurations, and more. In iOS, iPadOS and macOS 26, you can now build robust content filters that make traffic decisions using the entire URL — not just the hostname — all without compromising privacy and security. We’ll start by briefly covering many of the key use cases for the NetworkExtension framework, including network relays and VPN. Then, we’ll dive into the new URL filter API and its key components, including Private Information Retrieval, Privacy Pass, and more.

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Code shown on screen · 3 snippets

Use participation API to check URLs before sending requests swift · at 22:15 ↗ 
// Use participation API to check URLs before sending requests

import NetworkExtension

func checkURL(url: URL) async throws -> Bool {
  var passRequest : Bool = true

  let verdict = await NEURLFilter.verdict(for: url)

  if verdict == .deny {
    passRequest = false
  }
  return passRequest
}
Configure and manage URL Filter swift · at 25:01 ↗ 
// Configure and manage URL Filter

import NetworkExtension

let manager = NEURLFilterManager.shared

try await manager.loadFromPreferences()

try manager.setConfiguration(
    pirServerURL: URL(string:"https://pir.example.com")!,
    pirPrivacyPassIssuerURL: URL(string:"https://privacypass.example.com")!,
    pirAuthenticationToken: "1234",
    controlProviderBundleIdentifier: "com.example.myURLFilter.extension")

manager.prefilterFetchInterval = 86400 // fetch every 1 day
manager.shouldFailClosed = false
manager.localizedDescription = "Alice's URL Filter"
manager.isEnabled = true

try await manager.saveToPreferences()
Implement NEURLFilterControlProvider protocol swift · at 26:41 ↗ 
// Implement NEURLFilterControlProvider protocol

import NetworkExtension

class URLFilterControlProvider: NEURLFilterControlProvider {

  func fetchPrefilter() async throws -> NEURLFilterPrefilter? {
        
    // Fetch your Bloom filters data from your app bundle or from your server
    let data = NEURLFilterPrefilter.PrefilterData.temporaryFilepath(fileURL)
    let result = NEURLFilterPrefilter(data: data,
                                      bitCount: numberOfBits,
                                      hashCount: numberOfHashes,
                                      murmurSeed: murmurSeed)
    return result
  }
}

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