feat: UIKit instrumentation now sets the current view (#26)

## Which problem is this PR solving?
UIKit Instrumentation was emitting `viewDidAppear` and
`viewDidDisappear` events, but wasn't persisting the "current screen"
value as the SwiftUI Navigation instrumentation did in #23

## Short description of the changes
UIKit Instrumentation now tracks the "current screen" value

Computing "current screen" is a little complex but tldr we use the
following (in order of precedence):
- `accessiblityIdentifier`
- Storybook Identifier
- `view.title`
- current class name of the view controller

`honeycombIdentifier` is provided as an escape hatch for clients to opt
out of this precedence chain and set some explicit value

This PR also updates our smoke test app to use nested UIKit navigations
as a way to exercise the "current screen" computations.

Note that we don't do anything in the `viewDidDisappear` event: I
considered setting the current screen to `nil` but opted against that
because
1. it seemed like there were cases where, View B is replacing View A,
View A's `viewDidDisappear` would run _after_ View B's `viewDidAppear`.
Thus setting current screen to `nil` would actually clobber the (now
correct) value corresponding to whatever we get from View B
2. I reasoned that if one view is disappearing, then it must be replaced
by some other view, and that other view is responsible to setting
current screen (either automatically, if the new view is a UIKit view,
or explicitly, if it's a SwiftUI view)

## How to verify that this has the expected result
- [x] run the smoke test app and manually inspect collector output
- [x] updated smoke tests

Author: MustafaHaddara

Examples/SmokeTest/SmokeTest.xcodeproj/project.pbxproj

@@ -7,9 +7,9 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
-		452B71DD2CE52C8600C27FB2 /* ViewInstrumentationView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 452B71DC2CE52C8600C27FB2 /* ViewInstrumentationView.swift */; };
 		366309102CE51BDC00B97612 /* UIKitView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3663090F2CE51BDC00B97612 /* UIKitView.swift */; };
-		366309122CE51EF000B97612 /* UIKitView.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 366309112CE51EF000B97612 /* UIKitView.storyboard */; };
+		366309122CE51EF000B97612 /* UIKitViewStoryboard.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 366309112CE51EF000B97612 /* UIKitViewStoryboard.storyboard */; };
+		452B71DD2CE52C8600C27FB2 /* ViewInstrumentationView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 452B71DC2CE52C8600C27FB2 /* ViewInstrumentationView.swift */; };
 		452B71E12CE6A52600C27FB2 /* NavigationExamplesView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 452B71E02CE6A52600C27FB2 /* NavigationExamplesView.swift */; };
 		AF6DEFEA2C8D3CE000363027 /* SmokeTestApp.swift in Sources */ = {isa = PBXBuildFile; fileRef = AF6DEFE92C8D3CE000363027 /* SmokeTestApp.swift */; };
 		AF6DEFEC2C8D3CE000363027 /* ContentView.swift in Sources */ = {isa = PBXBuildFile; fileRef = AF6DEFEB2C8D3CE000363027 /* ContentView.swift */; };
@@ -41,9 +41,9 @@
 /* End PBXContainerItemProxy section */
 
 /* Begin PBXFileReference section */
-		452B71DC2CE52C8600C27FB2 /* ViewInstrumentationView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ViewInstrumentationView.swift; sourceTree = "<group>"; };
 		3663090F2CE51BDC00B97612 /* UIKitView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UIKitView.swift; sourceTree = "<group>"; };
-		366309112CE51EF000B97612 /* UIKitView.storyboard */ = {isa = PBXFileReference; lastKnownFileType = file.storyboard; path = UIKitView.storyboard; sourceTree = "<group>"; };
+		366309112CE51EF000B97612 /* UIKitViewStoryboard.storyboard */ = {isa = PBXFileReference; lastKnownFileType = file.storyboard; path = UIKitViewStoryboard.storyboard; sourceTree = "<group>"; };
+		452B71DC2CE52C8600C27FB2 /* ViewInstrumentationView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ViewInstrumentationView.swift; sourceTree = "<group>"; };
 		452B71E02CE6A52600C27FB2 /* NavigationExamplesView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NavigationExamplesView.swift; sourceTree = "<group>"; };
 		AF6DEFE62C8D3CE000363027 /* SmokeTest.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = SmokeTest.app; sourceTree = BUILT_PRODUCTS_DIR; };
 		AF6DEFE92C8D3CE000363027 /* SmokeTestApp.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SmokeTestApp.swift; sourceTree = "<group>"; };
@@ -118,7 +118,7 @@
 				AF6DEFED2C8D3CE100363027 /* Assets.xcassets */,
 				AF6DEFEF2C8D3CE100363027 /* Preview Content */,
 				3663090F2CE51BDC00B97612 /* UIKitView.swift */,
-				366309112CE51EF000B97612 /* UIKitView.storyboard */,
+				366309112CE51EF000B97612 /* UIKitViewStoryboard.storyboard */,
 			);
 			path = SmokeTest;
 			sourceTree = "<group>";
@@ -263,7 +263,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				AF6DEFF12C8D3CE100363027 /* Preview Assets.xcassets in Resources */,
-				366309122CE51EF000B97612 /* UIKitView.storyboard in Resources */,
+				366309122CE51EF000B97612 /* UIKitViewStoryboard.storyboard in Resources */,
 				AF6DEFEE2C8D3CE100363027 /* Assets.xcassets in Resources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

Examples/SmokeTest/SmokeTest/UIKitView.swift

@@ -16,20 +16,29 @@ struct UIKView_preview: PreviewProvider {
 
 struct StoryboardViewControllerRepresentation: UIViewControllerRepresentable {
     func makeUIViewController(context: Context) -> some UIViewController {
-        let storyboard = UIStoryboard(name: "UIKitView", bundle: Bundle.main)
-        let controller = storyboard.instantiateViewController(identifier: "UIKitView")
+        let storyboard = UIStoryboard(name: "UIKitViewStoryboard", bundle: Bundle.main)
+        let controller = storyboard.instantiateViewController(identifier: "UIKitNavigationRoot")
         return controller
     }
 
     func updateUIViewController(_ uiViewController: UIViewControllerType, context: Context) {
     }
 }
 
-class ViewController: UIViewController {
+class UIKitScreenViewController: UIViewController {
 
     override func viewDidLoad() {
         super.viewDidLoad()
+        self.title = "UIKit Screen"
         // Do any additional setup after loading the view.
     }
 
 }
+
+class UIKitMenuViewController: UIViewController {
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        title = "UIKit Menu"
+    }
+}

Examples/SmokeTest/SmokeTest/UIKitView.storyboard Examples/SmokeTest/SmokeTest/UIKitViewStoryboard.storyboard

@@ -8,10 +8,10 @@
         <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
     </dependencies>
     <scenes>
-        <!--View Controller-->
+        <!--Kit Screen View Controller-->
         <scene sceneID="s0d-6b-0kx">
             <objects>
-                <viewController storyboardIdentifier="UIKitView" id="Y6W-OH-hqX" customClass="ViewController" sceneMemberID="viewController">
+                <viewController id="Y6W-OH-hqX" customClass="UIKitScreenViewController" customModule="SmokeTest" customModuleProvider="target" sceneMemberID="viewController">
                     <view key="view" contentMode="scaleToFill" id="5EZ-qb-Rvc">
                         <rect key="frame" x="0.0" y="0.0" width="393" height="852"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
@@ -60,6 +60,9 @@
                         </subviews>
                         <viewLayoutGuide key="safeArea" id="vDu-zF-Fre"/>
                         <color key="backgroundColor" systemColor="systemBackgroundColor"/>
+                        <accessibility key="accessibilityConfiguration" identifier="UI KIT SCREEN OVERRIDE">
+                            <bool key="isElement" value="NO"/>
+                        </accessibility>
                         <constraints>
                             <constraint firstItem="vDu-zF-Fre" firstAttribute="trailing" secondItem="ks9-AV-zp6" secondAttribute="trailing" constant="16" id="34M-ZV-0ya"/>
                             <constraint firstItem="zfX-ff-qIS" firstAttribute="top" secondItem="DzX-1X-ZOc" secondAttribute="bottom" constant="16" id="3eY-tS-YQ1"/>
@@ -80,10 +83,59 @@
                             <constraint firstItem="008-k5-M1T" firstAttribute="centerX" secondItem="5EZ-qb-Rvc" secondAttribute="centerX" id="xun-d3-rYB"/>
                         </constraints>
                     </view>
+                    <navigationItem key="navigationItem" id="CFx-hq-SqH"/>
                 </viewController>
                 <placeholder placeholderIdentifier="IBFirstResponder" id="Ief-a0-LHa" userLabel="First Responder" customClass="UIResponder" sceneMemberID="firstResponder"/>
             </objects>
-            <point key="canvasLocation" x="61.832061068702288" y="3.5211267605633805"/>
+            <point key="canvasLocation" x="1915.2671755725189" y="3.5211267605633805"/>
+        </scene>
+        <!--Kit Menu View Controller-->
+        <scene sceneID="WJl-a9-s4a">
+            <objects>
+                <viewController id="bfq-Fn-kGB" customClass="UIKitMenuViewController" customModule="SmokeTest" customModuleProvider="target" sceneMemberID="viewController">
+                    <view key="view" contentMode="scaleToFill" id="uMH-m2-CcE">
+                        <rect key="frame" x="0.0" y="0.0" width="393" height="852"/>
+                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <subviews>
+                            <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="fill" contentVerticalAlignment="fill" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="7xf-19-0Op">
+                                <rect key="frame" x="0.0" y="401" width="393" height="51"/>
+                                <autoresizingMask key="autoresizingMask" flexibleMinX="YES" flexibleMaxX="YES" flexibleMinY="YES" flexibleMaxY="YES"/>
+                                <edgeInsets key="layoutMargins" top="8" left="8" bottom="8" right="8"/>
+                                <state key="normal" title="Button"/>
+                                <buttonConfiguration key="configuration" style="plain" title="Go To UIKit App" buttonSize="large" titleAlignment="center">
+                                    <fontDescription key="titleFontDescription" type="system" pointSize="20"/>
+                                </buttonConfiguration>
+                                <connections>
+                                    <segue destination="Y6W-OH-hqX" kind="show" id="CMK-mH-lON"/>
+                                </connections>
+                            </button>
+                        </subviews>
+                        <viewLayoutGuide key="safeArea" id="zJ1-ch-MPe"/>
+                        <color key="backgroundColor" systemColor="systemBackgroundColor"/>
+                    </view>
+                    <navigationItem key="navigationItem" id="sHW-hM-6E5"/>
+                </viewController>
+                <placeholder placeholderIdentifier="IBFirstResponder" id="3Fx-Ex-bh1" userLabel="First Responder" customClass="UIResponder" sceneMemberID="firstResponder"/>
+            </objects>
+            <point key="canvasLocation" x="1054.1984732824426" y="3.5211267605633805"/>
+        </scene>
+        <!--Navigation Controller-->
+        <scene sceneID="0Yh-qJ-qYw">
+            <objects>
+                <navigationController storyboardIdentifier="UIKitNavigationRoot" automaticallyAdjustsScrollViewInsets="NO" id="b2m-ne-2Y2" sceneMemberID="viewController">
+                    <toolbarItems/>
+                    <navigationBar key="navigationBar" contentMode="scaleToFill" id="2fV-z7-NIw">
+                        <rect key="frame" x="0.0" y="59" width="393" height="44"/>
+                        <autoresizingMask key="autoresizingMask"/>
+                    </navigationBar>
+                    <nil name="viewControllers"/>
+                    <connections>
+                        <segue destination="bfq-Fn-kGB" kind="relationship" relationship="rootViewController" id="bph-pf-i0m"/>
+                    </connections>
+                </navigationController>
+                <placeholder placeholderIdentifier="IBFirstResponder" id="Hr9-Vd-AxC" userLabel="First Responder" customClass="UIResponder" sceneMemberID="firstResponder"/>
+            </objects>
+            <point key="canvasLocation" x="127.48091603053435" y="3.5211267605633805"/>
         </scene>
     </scenes>
     <resources>

Examples/SmokeTest/SmokeTestUITests/SmokeTestUITests.swift

@@ -157,7 +157,7 @@ final class SmokeTestUITests: XCTestCase {
         let app = XCUIApplication()
         app.launch()
         app.buttons["UIKit"].tap()
-        XCTAssert(app.staticTexts["Sample UIKit App"].waitForExistence(timeout: uiUpdateTimeout))
+        XCTAssert(app.buttons["Go To UIKit App"].waitForExistence(timeout: uiUpdateTimeout))
 
         app.buttons["Core"].tap()
         XCTAssert(app.buttons["Flush"].waitForExistence(timeout: uiUpdateTimeout))
@@ -168,6 +168,9 @@ final class SmokeTestUITests: XCTestCase {
         let app = XCUIApplication()
         app.launch()
         app.buttons["UIKit"].tap()
+        XCTAssert(app.buttons["Go To UIKit App"].waitForExistence(timeout: uiUpdateTimeout))
+        app.buttons["Go To UIKit App"].tap()
+
         XCTAssert(app.staticTexts["Sample UIKit App"].waitForExistence(timeout: uiUpdateTimeout))
 
         app.buttons["Simple Button"].tap()

README.md

@@ -86,8 +86,15 @@ UIKit views will automatically be instrumented, emitting `viewDidAppear` and `vi
 - `view.title` - Title of the view controller, if provided.
 - `view.nibName` - The name of the view controller's nib file, if one was specified.
 - `view.animated` - true if the transition to/from this view is animated, false if it isn't.
-- `view.class` - name of the swift/objective-c class this view 
-controller has.
+- `view.class` - name of the swift/objective-c class this view controller has.
+- `screen.name` - name of the screen that appeared. In order of precedence, this attribute will have the value of the first of these to be set:
+    - `accessiblityIdentifier` of the view that appeared
+    - `view.title` - as defined above. If the view is a UINavigationController, Storybook Identifier (below) will be used in preference to `view.title`.
+    - Storybook Identifier - unique id identifying the view controller within its Storybook.
+    - `view.class` - as defined above
+- `screen.path` - the full path leading to the current view, consisting of the current view's `screen.name` as well as any parent views.
+    
+`viewDidAppear` events will also track `screen.name` as the "current screen" (as with the manual instrumentation described below), and will include that value as `screen.name` on other, non-navigation spans emitted. 
 
 #### Interaction
 

Sources/Honeycomb/HoneycombNavigationSpanInstrumentation.swift

@@ -15,7 +15,7 @@ func getTracer() -> Tracer {
 
 internal class HoneycombNavigationProcessor {
     static let shared = HoneycombNavigationProcessor()
-    var currentNavigationPath: String? = nil
+    var currentNavigationPath: [String] = []
 
     private init() {}
 
@@ -29,7 +29,7 @@ internal class HoneycombNavigationProcessor {
     }
 
     func reportNavigation(path: String) {
-        currentNavigationPath = path
+        currentNavigationPath = [path]
 
         // emit a span that says we've navigated to this path
         getTracer().spanBuilder(spanName: navigationSpanName)
@@ -71,6 +71,9 @@ internal class HoneycombNavigationProcessor {
         reportNavigation(path: unencodablePath)
     }
 
+    func setCurrentNavigationPath(_ path: [String]) {
+        currentNavigationPath = path
+    }
 }
 
 extension View {
@@ -96,15 +99,28 @@ public struct HoneycombNavigationPathSpanProcessor: SpanProcessor {
         parentContext: SpanContext?,
         span: any ReadableSpan
     ) {
-        if HoneycombNavigationProcessor.shared.currentNavigationPath != nil {
+        let currentViewPath = HoneycombNavigationProcessor.shared.currentNavigationPath
+        if !currentViewPath.isEmpty {
             span.setAttribute(
                 key: "screen.name",
-                value: HoneycombNavigationProcessor.shared.currentNavigationPath!
+                value: currentViewPath.last!
+            )
+            span.setAttribute(
+                key: "screen.path",
+                value: serializePath(currentViewPath)
             )
-
         }
     }
 
+    private func serializePath(_ path: [String]) -> String {
+        return
+            path
+            .filter { str in
+                !str.starts(with: ("_"))
+            }
+            .joined(separator: "/")
+    }
+
     public func onEnd(span: any ReadableSpan) {}
 
     public func shutdown(explicitTimeout: TimeInterval? = nil) {}

Sources/Honeycomb/UIKit/UIViewController.swift

@@ -4,6 +4,33 @@
     import UIKit
 
     extension UIViewController {
+        var storyboardId: String? {
+            return value(forKey: "storyboardIdentifier") as? String
+        }
+
+        private var viewName: String {
+            // prefer storyboardId over title for UINavigationController
+            // prefer title over storyboardId for other classes
+            if self.isKind(of: UINavigationController.self) {
+                return self.view.accessibilityIdentifier
+                    ?? self.storyboardId
+                    ?? self.title
+                    ?? NSStringFromClass(type(of: self))
+            }
+            return self.view.accessibilityIdentifier
+                ?? self.title
+                ?? self.storyboardId
+                ?? NSStringFromClass(type(of: self))
+        }
+
+        private func viewStack() -> [String] {
+            if var parentPath = self.parent?.viewStack() {
+                parentPath.append(self.viewName)
+                return parentPath
+            }
+            return [self.viewName]
+        }
+
         private func setAttributes(span: Span, className: String, animated: Bool) {
             if let title = self.title {
                 span.setAttribute(key: "view.title", value: title)
@@ -20,6 +47,9 @@
 
             // Internal classes from SwiftUI will likely begin with an underscore
             if !className.hasPrefix("_") {
+                // set this _before_ creating the span
+                HoneycombNavigationProcessor.shared.setCurrentNavigationPath(viewStack())
+
                 let span = getUIKitViewTracer().spanBuilder(spanName: "viewDidAppear").startSpan()
                 setAttributes(span: span, className: className, animated: animated)
                 span.end()