Create user agent on main queue (#175)

* Create user agent on main queue
Refactor duplicate code into common method

* Removed custom asyncMain function

* Added a line to the CHANGELOG

CHANGELOG.md

@@ -1,5 +1,8 @@
 # Changelog
 
+## Unreleased
+* **improvement** The PiwikTracker is now save to create in a background thread. [#175](https://github.com/piwik/piwik-sdk-ios/pull/175)
+
 ## 4.3.0
 * **feature** Added the ability to send custom events with custom tracking parameters. [#153](https://github.com/piwik/piwik-sdk-ios/issues/153)
 * **bugfix** Fixed a crash when initializing a new tracker. [#162](https://github.com/piwik/piwik-sdk-ios/issues/162)

PiwikTracker.xcodeproj/project.pbxproj

@@ -24,6 +24,7 @@
 		1F6F0CDE1E61E377008170FC /* TrackerFixtures.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1F6F0CDA1E61E377008170FC /* TrackerFixtures.swift */; };
 		1F6F0CDF1E61E377008170FC /* TrackerSpec.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1F6F0CDB1E61E377008170FC /* TrackerSpec.swift */; };
 		1F6F0CE11E61E4F3008170FC /* URLSessionDispatcher.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1F6F0CE01E61E4F3008170FC /* URLSessionDispatcher.swift */; };
+		1F7C667F1F8C096F0066CC64 /* MainThread.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1F7C667E1F8C096F0066CC64 /* MainThread.swift */; };
 		1F80856F1E6B4B9800A61AAF /* Locale+HttpAcceptLanguage.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1F80856E1E6B4B9800A61AAF /* Locale+HttpAcceptLanguage.swift */; };
 		1FCA6D451DBE0B2F0033F01C /* PiwikTracker.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 1FCA6D3B1DBE0B2F0033F01C /* PiwikTracker.framework */; };
 		1FCA6D4C1DBE0B2F0033F01C /* PiwikTracker.h in Headers */ = {isa = PBXBuildFile; fileRef = 1FCA6D3E1DBE0B2F0033F01C /* PiwikTracker.h */; settings = {ATTRIBUTES = (Public, ); }; };
@@ -61,6 +62,7 @@
 		1F6F0CDA1E61E377008170FC /* TrackerFixtures.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TrackerFixtures.swift; sourceTree = "<group>"; };
 		1F6F0CDB1E61E377008170FC /* TrackerSpec.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TrackerSpec.swift; sourceTree = "<group>"; };
 		1F6F0CE01E61E4F3008170FC /* URLSessionDispatcher.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = URLSessionDispatcher.swift; sourceTree = "<group>"; };
+		1F7C667E1F8C096F0066CC64 /* MainThread.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MainThread.swift; sourceTree = "<group>"; };
 		1F80856E1E6B4B9800A61AAF /* Locale+HttpAcceptLanguage.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "Locale+HttpAcceptLanguage.swift"; sourceTree = "<group>"; };
 		1FCA6D3B1DBE0B2F0033F01C /* PiwikTracker.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = PiwikTracker.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		1FCA6D3E1DBE0B2F0033F01C /* PiwikTracker.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = PiwikTracker.h; sourceTree = "<group>"; };
@@ -157,6 +159,7 @@
 				1F38EBF71EE568D10021FBF8 /* Logger.swift */,
 				1FDC917D1F1A65150046F506 /* Application.swift */,
 				1FDC917E1F1A65150046F506 /* Device.swift */,
+				1F7C667E1F8C096F0066CC64 /* MainThread.swift */,
 				1FCA6D3F1DBE0B2F0033F01C /* Info.plist */,
 				1FCA6D3E1DBE0B2F0033F01C /* PiwikTracker.h */,
 			);
@@ -375,6 +378,7 @@
 				1F092C1A1E26B44500394B30 /* Dispatcher.swift in Sources */,
 				1F38EBF81EE568D10021FBF8 /* Logger.swift in Sources */,
 				1FCFF0241F82C7A50038BC17 /* CustomDimension.swift in Sources */,
+				1F7C667F1F8C096F0066CC64 /* MainThread.swift in Sources */,
 				1F80856F1E6B4B9800A61AAF /* Locale+HttpAcceptLanguage.swift in Sources */,
 				1F0A15CE1E6335D800FEAE72 /* Visitor.swift in Sources */,
 				1FDC917F1F1A65150046F506 /* Application.swift in Sources */,

PiwikTracker/MainThread.swift

@@ -0,0 +1,5 @@
+import Foundation
+
+func assetMainThread(_ file: StaticString = #file, line: UInt = #line) {
+    assert(Thread.isMainThread, "\(file):\(line) must run on the main thread!")
+}

PiwikTracker/PiwikTracker.swift

@@ -69,6 +69,8 @@ final public class PiwikTracker: NSObject {
     ///   - baseURL: The url of the piwik server. This url has to end in `piwik.php`.
     ///   - userAgent: An optional parameter for custom user agent.
     convenience public init(siteId: String, baseURL: URL, userAgent: String? = nil) {
+        assert(baseURL.absoluteString.hasSuffix("piwik.php"), "The baseURL is expected to end in piwik.php")
+
         let queue = MemoryQueue()
         let dispatcher = URLSessionDispatcher(baseURL: baseURL, userAgent: userAgent)
         self.init(siteId: siteId, queue: queue, dispatcher: dispatcher)

PiwikTracker/URLSessionDispatcher.swift

@@ -12,46 +12,44 @@ final class URLSessionDispatcher: Dispatcher {
     let session: URLSession
     let baseURL: URL
 
-    var userAgent: String? = {
-        #if os(OSX)
-            let webView = WebView(frame: .zero)
-            let currentUserAgent = webView.stringByEvaluatingJavaScript(from: "navigator.userAgent") ?? ""
-        #elseif os(iOS)
-            let webView = UIWebView(frame: .zero)
-            let currentUserAgent = webView.stringByEvaluatingJavaScript(from: "navigator.userAgent") ?? ""
-        #elseif os(tvOS)
-            let currentUserAgent = ""
-        #endif
-        return currentUserAgent.appending(" PiwikTracker SDK URLSessionDispatcher")
-    }()
+    private(set) var userAgent: String?
 
     /// Generate a URLSessionDispatcher instance
     ///
     /// - Parameters:
     ///   - baseURL: The url of the piwik server. This url has to end in `piwik.php`.
     ///   - userAgent: An optional parameter for custom user agent.
-    init(baseURL: URL, userAgent: String? = nil) {
-        if !baseURL.absoluteString.hasSuffix("piwik.php") {
-            fatalError("The baseURL is expected to end in piwik.php")
-        }
+    init(baseURL: URL, userAgent: String? = nil) {                
         self.baseURL = baseURL
         self.timeout = 5
         self.session = URLSession.shared
-        if (userAgent != nil) {
-            self.userAgent = userAgent
+        DispatchQueue.main.async {
+            self.userAgent = userAgent ?? URLSessionDispatcher.defaultUserAgent()
         }
     }
 
+    private static func defaultUserAgent() -> String {
+        assetMainThread()
+        #if os(OSX)
+            let webView = WebView(frame: .zero)
+            let currentUserAgent = webView.stringByEvaluatingJavaScript(from: "navigator.userAgent") ?? ""
+        #elseif os(iOS)
+            let webView = UIWebView(frame: .zero)
+            let currentUserAgent = webView.stringByEvaluatingJavaScript(from: "navigator.userAgent") ?? ""
+        #elseif os(tvOS)
+            let currentUserAgent = ""
+        #endif
+        return currentUserAgent.appending(" PiwikTracker SDK URLSessionDispatcher")
+    }
+
     func send(event: Event, success: @escaping ()->(), failure: @escaping (_ error: Error)->()) {
         let url = baseURL.setting(event.queryItems)
-        var request = URLRequest(url: url, cachePolicy: .reloadIgnoringCacheData, timeoutInterval: timeout)
-        request.setValue(userAgent, forHTTPHeaderField: "User-Agent")
-        request.httpMethod = "GET"
+        let request = buildRequest(baseURL: url, method: "GET")
         send(request: request, success: success, failure: failure)
     }
 
     func send(events: [Event], success: @escaping ()->(), failure: @escaping (_ error: Error)->()) {
-        let eventsAsQueryItems = events.map({ event in event.queryItems })
+        let eventsAsQueryItems = events.map({ $0.queryItems })
         let serializedEvents = eventsAsQueryItems.map({ items in
             items.flatMap({ item in
                 guard let value = item.value,
@@ -67,14 +65,19 @@ final class URLSessionDispatcher: Dispatcher {
             failure(error)
             return
         }
-        var request = URLRequest(url: baseURL, cachePolicy: .reloadIgnoringCacheData, timeoutInterval: timeout)
-        request.setValue("application/json; charset=utf-8", forHTTPHeaderField: "Content-Type")
-        request.setValue(userAgent, forHTTPHeaderField: "User-Agent")
-        request.httpMethod = "POST"
-        request.httpBody = jsonBody
+        let request = buildRequest(baseURL: baseURL, method: "POST", contentType: "application/json; charset=utf-8", body: jsonBody)
         send(request: request, success: success, failure: failure)
     }
 
+    private func buildRequest(baseURL: URL, method: String, contentType: String? = nil, body: Data? = nil) -> URLRequest {
+        var request = URLRequest(url: baseURL, cachePolicy: .reloadIgnoringCacheData, timeoutInterval: timeout)
+        request.httpMethod = method
+        body.map { request.httpBody = $0 }
+        contentType.map { request.setValue($0, forHTTPHeaderField: "Content-Type") }
+        userAgent.map { request.setValue($0, forHTTPHeaderField: "User-Agent") }
+        return request
+    }
+
     private func send(request: URLRequest, success: @escaping ()->(), failure: @escaping (_ error: Error)->()) {
         let task = session.dataTask(with: request) { data, response, error in
             // should we check the response?
@@ -93,7 +96,7 @@ final class URLSessionDispatcher: Dispatcher {
 fileprivate extension Event {
     var queryItems: [URLQueryItem] {
         get {
-            var items = [
+            let items = [
                 URLQueryItem(name: "idsite", value: siteId),
                 URLQueryItem(name: "rec", value: "1"),
                 // Visitor
@@ -115,7 +118,6 @@ fileprivate extension Event {
                 URLQueryItem(name: "m", value: DateFormatter.minuteDateFormatter.string(from: date)),
                 URLQueryItem(name: "s", value: DateFormatter.secondsDateFormatter.string(from: date)),
 
-
                 //screen resolution
                 URLQueryItem(name: "res", value:String(format: "%1.0fx%1.0f", screenResolution.width, screenResolution.height)),
 
@@ -124,11 +126,11 @@ fileprivate extension Event {
                 URLQueryItem(name: "e_n", value: eventName),
                 URLQueryItem(name: "e_v", value: eventValue != nil ? "\(eventValue!)" : nil),
 
-                ].filter({ $0.value != nil }) // remove the items that lack the value
-            for dimension in dimensions {
-                items.append(URLQueryItem(name: "dimension\(dimension.index)", value: dimension.value))
-            }
-            return items + customTrackingParameters.map({ key, value in return URLQueryItem(name: key, value: value) })
+                ].filter { $0.value != nil }
+
+            let dimensionItems = dimensions.map { URLQueryItem(name: "dimension\($0.index)", value: $0.value) }
+            let customItems = customTrackingParameters.map { return URLQueryItem(name: $0.key, value: $0.value) }
+            return items + dimensionItems + customItems
         }
     }
 }

README.md

@@ -129,7 +129,7 @@ PiwikTracker.shared?.logger = DefaultLogger(minLevel: .error)
 You can also write your own `Logger` and send the logs whereever you want. Just write a new class/struct an let it conform to the `Logger` protocol.
 
 ### Custom User Agent
-The `PiwikTracker` will create a default user agent derived from the WKWebView user agent. This is why you should always instantiate and configure the `PiwikTracker` on the main thread.
+The `PiwikTracker` will create a default user agent derived from the WKWebView user agent.
 You can instantiate the `PiwikTracker` using your own user agent.
 
 ```