feat!: send user agent header

.github/pull_request_template.md

@@ -0,0 +1,29 @@
+<!--
+  Provide a description of your changes below and a general summary in the title.
+  Please also provide some test recommendations if necessary to ensure we don't have regressions.
+  Please look at the following checklist to ensure that your PR can be accepted quickly:
+-->
+
+## Description
+
+<!--- Describe your changes in detail -->
+
+## Regression Test Recommendations
+
+<!--- Functionality that could be affected by the change and any other concerns -->
+
+## Type of Change
+
+<!--- Put an `x` in all the boxes that apply: -->
+
+- [ ] ✨ New feature (non-breaking change which adds functionality)
+- [ ] 🛠️ Bug fix (non-breaking change which fixes an issue)
+- [ ] ❌ Breaking change (fix or feature that would cause existing functionality to change)
+- [ ] 🧹 Code refactor
+- [ ] ✅ Build configuration change
+- [ ] 📝 Documentation
+- [ ] 🗑️ Chore
+
+## Estimated time to fix the ticket(s) or epic(s) referenced by the PR in days
+
+<!--- Add estimate to complete the work -->

FlagsmithClient/Classes/Flagsmith.swift

@@ -17,6 +17,39 @@ typealias CompletionHandler<T> = @Sendable (Result<T, any Error>) -> Void
 public final class Flagsmith: @unchecked Sendable {
     /// Shared singleton client object
     public static let shared: Flagsmith = .init()
+
+    /// SDK version constant - should match the podspec version
+    /// This is used as a fallback when bundle version detection fails
+    private static let sdkVersionConstant = "3.8.4"
+
+    /// User-Agent header value for HTTP requests
+    /// Format: flagsmith-swift-ios-sdk/<version>
+    /// Falls back to "unknown" if version is not discoverable at runtime
+    public static let userAgent: String {
+        let version = getSDKVersion()
+        return "flagsmith-swift-ios-sdk/\(version)"
+    }
+
+    /// Get the SDK version from the bundle at runtime
+    /// Falls back to hardcoded constant or "unknown" if version is not discoverable
+    private static func getSDKVersion() -> String {
+        // Try CocoaPods bundle first
+        if let bundle = Bundle(identifier: "org.cocoapods.FlagsmithClient"),
+        let version = bundle.infoDictionary?["CFBundleShortVersionString"] as? String, 
+        !version.isEmpty,
+        version.range(of: #"^\d+\.\d+\.\d+"#, options: .regularExpression) != nil {
+            return version
+        }
+
+        // Try SPM bundle
+        if let version = Bundle(for: Flagsmith.self).infoDictionary?["CFBundleShortVersionString"] as? String,
+        !version.isEmpty,
+        version.range(of: #"^\d+\.\d+\.\d+"#, options: .regularExpression) != nil {
+            return version
+        }
+
+        return "unknown"
+    }
     private let apiManager: APIManager
     private let sseManager: SSEManager
     private let analytics: FlagsmithAnalytics

FlagsmithClient/Classes/Internal/Router.swift

@@ -100,8 +100,9 @@ enum Router: Sendable {
         if let body = try body(using: encoder) {
             request.httpBody = body
         }
-        request.addValue(apiKey, forHTTPHeaderField: "X-Environment-Key")
-        request.addValue("application/json", forHTTPHeaderField: "Content-Type")
+        request.setValue(apiKey, forHTTPHeaderField: "X-Environment-Key")
+        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
+        request.setValue(Flagsmith.userAgent, forHTTPHeaderField: "User-Agent")
 
         return request
     }

FlagsmithClient/Classes/Internal/SSEManager.swift

@@ -157,6 +157,7 @@ final class SSEManager: NSObject, URLSessionDataDelegate, @unchecked Sendable {
         request.setValue("text/event-stream, application/json; charset=utf-8", forHTTPHeaderField: "Accept")
         request.setValue("no-cache", forHTTPHeaderField: "Cache-Control")
         request.setValue("keep-alive", forHTTPHeaderField: "Connection")
+        request.setValue(Flagsmith.userAgent, forHTTPHeaderField: "User-Agent")
 
         completionHandler = completion
         dataTask = session.dataTask(with: request)

FlagsmithClient/Tests/RouterTests.swift

@@ -21,6 +21,42 @@ final class RouterTests: FlagsmithClientTestCase {
         XCTAssertTrue(request.allHTTPHeaderFields?.contains(where: { $0.key == "X-Environment-Key" }) ?? false)
         XCTAssertNil(request.httpBody)
     }
+
+    func testUserAgentHeader() throws {
+        let url = try XCTUnwrap(baseUrl)
+        let route = Router.getFlags
+        let request = try route.request(baseUrl: url, apiKey: apiKey)
+
+        // Verify User-Agent header is present
+        XCTAssertTrue(request.allHTTPHeaderFields?.contains(where: { $0.key == "User-Agent" }) ?? false)
+
+        // Verify User-Agent header format
+        let userAgent = request.allHTTPHeaderFields?["User-Agent"]
+        XCTAssertNotNil(userAgent)
+        XCTAssertTrue(userAgent?.hasPrefix("flagsmith-swift-ios-sdk/") ?? false)
+
+        // Verify the format is correct (should end with a semantic version number)
+        let expectedPattern = "^flagsmith-swift-ios-sdk/[0-9]+\\.[0-9]+\\.[0-9]+$"
+        let regex = try NSRegularExpression(pattern: expectedPattern)
+        let range = NSRange(location: 0, length: userAgent?.count ?? 0)
+        let match = regex.firstMatch(in: userAgent ?? "", options: [], range: range)
+        let message = "User-Agent should match pattern 'flagsmith-swift-ios-sdk/<version>', got: \(userAgent ?? "nil")"
+        XCTAssertTrue(match != nil, message)
+    }
+
+    func testUserAgentHeaderFormat() {
+        // Test that the User-Agent format is correct
+        let userAgent = Flagsmith.userAgent
+        XCTAssertTrue(userAgent.hasPrefix("flagsmith-swift-ios-sdk/"))
+
+        // Should have a semantic version number (e.g., 3.8.4)
+        let versionPart = String(userAgent.dropFirst("flagsmith-swift-ios-sdk/".count))
+        XCTAssertTrue(versionPart.range(of: #"^\d+\.\d+\.\d+$"#, options: NSString.CompareOptions.regularExpression) != nil,
+                     "Version part should be a semantic version number (e.g., 3.8.4), got: \(versionPart)")
+
+        // Should be the expected SDK version
+        XCTAssertEqual(versionPart, "3.8.4", "Expected SDK version 3.8.4, got: \(versionPart)")
+    }
 
     func testGetIdentityRequest() throws {
         let url = try XCTUnwrap(baseUrl)