Customize requests HTTP headers

README.md

@@ -84,6 +84,14 @@ Turbolinks calls `session:didFailRequestForVisitable:withError:` when a visit’
 
 See [Handling Failed Requests](#handling-failed-requests) for more details.
 
+## Customizing HTTP Headers
+
+You can customize the headers sent when loading the first page and when navigating by giving them to the session upon its creation.
+
+```swift
+let session = Session(webViewConfiguration: self.webViewConfiguration, headers: [ "X-Custom": "foo" ])
+```
+
 ## Working with Visitables
 
 Visitable view controllers must conform to the Visitable protocol by implementing the following three properties:

Turbolinks.xcodeproj/project.pbxproj

@@ -7,6 +7,7 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		0391476C20AAC1C5009D356B /* WKWebViewConfiguration+.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0391476B20AAC1C5009D356B /* WKWebViewConfiguration+.swift */; };
 		1F8FC6B31B55A37400A781C8 /* WebView.js in Resources */ = {isa = PBXBuildFile; fileRef = 1F8FC6AE1B55A37400A781C8 /* WebView.js */; };
 		1F8FC6B71B55A37400A781C8 /* Session.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1F8FC6B01B55A37400A781C8 /* Session.swift */; };
 		1F8FC6B91B55A37400A781C8 /* Visit.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1F8FC6B11B55A37400A781C8 /* Visit.swift */; };
@@ -32,6 +33,7 @@
 /* End PBXContainerItemProxy section */
 
 /* Begin PBXFileReference section */
+		0391476B20AAC1C5009D356B /* WKWebViewConfiguration+.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "WKWebViewConfiguration+.swift"; sourceTree = "<group>"; };
 		1F8FC6AE1B55A37400A781C8 /* WebView.js */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.javascript; path = WebView.js; sourceTree = "<group>"; };
 		1F8FC6B01B55A37400A781C8 /* Session.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Session.swift; sourceTree = "<group>"; };
 		1F8FC6B11B55A37400A781C8 /* Visit.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Visit.swift; sourceTree = "<group>"; };
@@ -98,6 +100,7 @@
 				2286D72E1C81FCF500E34B1D /* VisitableView.swift */,
 				2286D7591C83F7C600E34B1D /* VisitableViewController.swift */,
 				22C197DD1B59835300749B4E /* WebView.swift */,
+				0391476B20AAC1C5009D356B /* WKWebViewConfiguration+.swift */,
 				1FC167F21B55A14900AA6F43 /* Supporting Files */,
 			);
 			path = Turbolinks;
@@ -235,6 +238,7 @@
 			files = (
 				2286D72F1C81FCF500E34B1D /* VisitableView.swift in Sources */,
 				22960AAB1B9F51E100AA144A /* ScriptMessage.swift in Sources */,
+				0391476C20AAC1C5009D356B /* WKWebViewConfiguration+.swift in Sources */,
 				2286D75A1C83F7C600E34B1D /* VisitableViewController.swift in Sources */,
 				1F8FC6B71B55A37400A781C8 /* Session.swift in Sources */,
 				1F8FC6BB1B55A37400A781C8 /* Visitable.swift in Sources */,

Turbolinks/Session.swift

@@ -26,6 +26,8 @@ public extension SessionDelegate {
     }
 }
 
+public typealias HTTPHeaders = [String: String]
+
 open class Session: NSObject {
     open weak var delegate: SessionDelegate?
 
@@ -36,10 +38,16 @@ open class Session: NSObject {
     fileprivate var _webView: WebView
     fileprivate var initialized = false
     fileprivate var refreshing = false
+
+    private let headers: HTTPHeaders?
 
-    public init(webViewConfiguration: WKWebViewConfiguration) {
+    public init(webViewConfiguration: WKWebViewConfiguration, headers: HTTPHeaders? = nil) {
+        webViewConfiguration.customizeTurbolinksAjaxRequests(withHeaders: headers)
         _webView = WebView(configuration: webViewConfiguration)
+        self.headers = headers
+
         super.init()
+
         _webView.delegate = self
     }
 
@@ -71,7 +79,7 @@ open class Session: NSObject {
             visit = JavaScriptVisit(visitable: visitable, action: action, webView: _webView)
             visit.restorationIdentifier = restorationIdentifierForVisitable(visitable)
         } else {
-            visit = ColdBootVisit(visitable: visitable, action: action, webView: _webView)
+            visit = ColdBootVisit(visitable: visitable, action: action, webView: _webView, headers: headers)
         }
 
         currentVisit?.cancel()

Turbolinks/Visit.swift

@@ -135,13 +135,22 @@ class Visit: NSObject {
 }
 
 class ColdBootVisit: Visit, WKNavigationDelegate, WebViewPageLoadDelegate {
+    init(visitable: Visitable, action: Action, webView: WebView, headers: HTTPHeaders? = nil) {
+        self.headers = headers
+
+        super.init(visitable: visitable, action: action, webView: webView)
+    }
+
+    private let headers: HTTPHeaders?
+
     fileprivate var navigation: WKNavigation?
 
     override fileprivate func startVisit() {
         webView.navigationDelegate = self
         webView.pageLoadDelegate = self
 
-        let request = URLRequest(url: location)
+        var request = URLRequest(url: location)
+        request.allHTTPHeaderFields = headers
         navigation = webView.load(request)
 
         delegate?.visitDidStart(self)

Turbolinks/WKWebViewConfiguration+.swift

@@ -0,0 +1,23 @@
+//
+//  Copyright © 2018 Basecamp. All rights reserved.
+//
+
+import WebKit
+
+extension WKWebViewConfiguration {
+    func customizeTurbolinksAjaxRequests(withHeaders headers: HTTPHeaders?) {
+        guard let headers = headers else { return }
+
+        let headersContent = headers.map {
+            return "event.data.xhr.setRequestHeader('\($0)', '\($1)');"
+        }.joined()
+
+        let scriptContent = """
+            document.addEventListener("turbolinks:request-start", function(event) { \(headersContent) });
+        """
+
+        let script = WKUserScript(source: scriptContent, injectionTime: .atDocumentStart, forMainFrameOnly: true)
+
+        userContentController.addUserScript(script)
+    }
+}

TurbolinksDemo/ApplicationController.swift

@@ -19,7 +19,7 @@ class ApplicationController: UINavigationController {
     }()
 
     fileprivate lazy var session: Session = {
-        let session = Session(webViewConfiguration: self.webViewConfiguration)
+        let session = Session(webViewConfiguration: self.webViewConfiguration, headers: [ "X-Custom": "foo" ])
         session.delegate = self
         return session
     }()

TurbolinksDemo/server/lib/turbolinks_demo/app.rb

@@ -7,6 +7,10 @@ module TurbolinksDemo
   class App < Sinatra::Base
     helpers Sinatra::Cookies
 
+    before do
+      puts "X-Custom = #{request.env["HTTP_X_CUSTOM"]}"
+    end
+
     get '/' do
       @title = 'Demo'
       erb :index, layout: :layout