chore: migrate UUID from v4 to v7

CHANGELOG.md

@@ -1,14 +1,16 @@
 ## Next
 
+- chore: migrate UUID from v4 to v7 ([#145](https://github.com/PostHog/posthog-ios/pull/145))
+
 ## 3.5.1 - 2024-06-12
 
-- recording: fix `screenshotMode` typo ([#143](https://github.com/PostHog/posthog-android/pull/143))
+- recording: fix `screenshotMode` typo ([#143](https://github.com/PostHog/posthog-ios/pull/143))
 
 ## 3.5.0 - 2024-06-11
 
 - chore: change host to new address ([#139](https://github.com/PostHog/posthog-ios/pull/139))
 - fix: rename groupProperties to groups for capture methods ([#140](https://github.com/PostHog/posthog-ios/pull/140))
-- recording: add `screenshotMode` option for session replay instead of wireframe ([#142](https://github.com/PostHog/posthog-android/pull/142))
+- recording: add `screenshotMode` option for session replay instead of wireframe ([#142](https://github.com/PostHog/posthog-ios/pull/142))
 
 ## 3.4.0 - 2024-05-23
 

PostHog.xcodeproj/project.pbxproj

@@ -33,6 +33,7 @@
 		3AE3FB49299391DF00AFFC18 /* PostHogStorage.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3AE3FB48299391DF00AFFC18 /* PostHogStorage.swift */; };
 		3AE3FB4B2993A68500AFFC18 /* PostHogStorageTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3AE3FB4A2993A68500AFFC18 /* PostHogStorageTest.swift */; };
 		3AE3FB4E2993D1D600AFFC18 /* PostHogSessionManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3AE3FB4D2993D1D600AFFC18 /* PostHogSessionManager.swift */; };
+		690B2DF32C205B5600AE3B45 /* TimeBasedEpochGenerator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 690B2DF22C205B5600AE3B45 /* TimeBasedEpochGenerator.swift */; };
 		690FF05F2AE7E2D400A0B06B /* Data+Gzip.swift in Sources */ = {isa = PBXBuildFile; fileRef = 690FF05E2AE7E2D400A0B06B /* Data+Gzip.swift */; };
 		690FF0AF2AEB9C1400A0B06B /* DateUtils.swift in Sources */ = {isa = PBXBuildFile; fileRef = 690FF0AE2AEB9C1400A0B06B /* DateUtils.swift */; };
 		690FF0B52AEBBD3C00A0B06B /* DictUtils.swift in Sources */ = {isa = PBXBuildFile; fileRef = 690FF0B42AEBBD3C00A0B06B /* DictUtils.swift */; };
@@ -81,6 +82,8 @@
 		699991942AFE1B56000DCB78 /* PostHog.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 3AC745B5296D6FE60025C109 /* PostHog.framework */; };
 		699991952AFE1B56000DCB78 /* PostHog.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = 3AC745B5296D6FE60025C109 /* PostHog.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
 		6999919A2AFE1BAB000DCB78 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 699991992AFE1BAB000DCB78 /* AppDelegate.swift */; };
+		699C5FE62C20178E007DB818 /* UUIDUtils.swift in Sources */ = {isa = PBXBuildFile; fileRef = 699C5FE52C20178E007DB818 /* UUIDUtils.swift */; };
+		699C5FEF2C20242A007DB818 /* UUIDTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = 699C5FEE2C20242A007DB818 /* UUIDTest.swift */; };
 		69BA38D72B888E8500AA69D6 /* PrivacyInfo.xcprivacy in Resources */ = {isa = PBXBuildFile; fileRef = 69BA38D62B888E8500AA69D6 /* PrivacyInfo.xcprivacy */; };
 		69EE82BA2BA9C50400EB9542 /* PostHogReplayIntegration.swift in Sources */ = {isa = PBXBuildFile; fileRef = 69EE82B92BA9C50400EB9542 /* PostHogReplayIntegration.swift */; };
 		69EE82BC2BA9C53000EB9542 /* PostHogSessionReplayConfig.swift in Sources */ = {isa = PBXBuildFile; fileRef = 69EE82BB2BA9C53000EB9542 /* PostHogSessionReplayConfig.swift */; };
@@ -276,6 +279,7 @@
 		3AE3FB48299391DF00AFFC18 /* PostHogStorage.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PostHogStorage.swift; sourceTree = "<group>"; };
 		3AE3FB4A2993A68500AFFC18 /* PostHogStorageTest.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PostHogStorageTest.swift; sourceTree = "<group>"; };
 		3AE3FB4D2993D1D600AFFC18 /* PostHogSessionManager.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PostHogSessionManager.swift; sourceTree = "<group>"; };
+		690B2DF22C205B5600AE3B45 /* TimeBasedEpochGenerator.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TimeBasedEpochGenerator.swift; sourceTree = "<group>"; };
 		690FF02F2AE7C5BA00A0B06B /* PostHogExampleWithPods.xcodeproj */ = {isa = PBXFileReference; lastKnownFileType = "wrapper.pb-project"; name = PostHogExampleWithPods.xcodeproj; path = PostHogExampleWithPods/PostHogExampleWithPods.xcodeproj; sourceTree = "<group>"; };
 		690FF0532AE7DB3700A0B06B /* PostHogExampleWithSPM.xcodeproj */ = {isa = PBXFileReference; lastKnownFileType = "wrapper.pb-project"; name = PostHogExampleWithSPM.xcodeproj; path = PostHogExampleWithSPM/PostHogExampleWithSPM.xcodeproj; sourceTree = "<group>"; };
 		690FF05E2AE7E2D400A0B06B /* Data+Gzip.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Data+Gzip.swift"; sourceTree = "<group>"; };
@@ -326,6 +330,8 @@
 		6999918E2AFE1B39000DCB78 /* Preview Assets.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = "Preview Assets.xcassets"; sourceTree = "<group>"; };
 		699991902AFE1B39000DCB78 /* PostHogExampleMacOS.entitlements */ = {isa = PBXFileReference; lastKnownFileType = text.plist.entitlements; path = PostHogExampleMacOS.entitlements; sourceTree = "<group>"; };
 		699991992AFE1BAB000DCB78 /* AppDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
+		699C5FE52C20178E007DB818 /* UUIDUtils.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UUIDUtils.swift; sourceTree = "<group>"; };
+		699C5FEE2C20242A007DB818 /* UUIDTest.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UUIDTest.swift; sourceTree = "<group>"; };
 		69BA38D62B888E8500AA69D6 /* PrivacyInfo.xcprivacy */ = {isa = PBXFileReference; lastKnownFileType = text.xml; path = PrivacyInfo.xcprivacy; sourceTree = "<group>"; };
 		69EE82B92BA9C50400EB9542 /* PostHogReplayIntegration.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PostHogReplayIntegration.swift; sourceTree = "<group>"; };
 		69EE82BB2BA9C53000EB9542 /* PostHogSessionReplayConfig.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PostHogSessionReplayConfig.swift; sourceTree = "<group>"; };
@@ -470,6 +476,8 @@
 				690FF0BE2AEFA97F00A0B06B /* FileUtils.swift */,
 				690FF0B42AEBBD3C00A0B06B /* DictUtils.swift */,
 				690FF0AE2AEB9C1400A0B06B /* DateUtils.swift */,
+				699C5FE52C20178E007DB818 /* UUIDUtils.swift */,
+				690B2DF22C205B5600AE3B45 /* TimeBasedEpochGenerator.swift */,
 			);
 			path = Utils;
 			sourceTree = "<group>";
@@ -548,6 +556,7 @@
 				690FF0E22AEFD12900A0B06B /* PostHogConfigTest.swift */,
 				690FF0E82AEFD3BD00A0B06B /* PostHogQueueTest.swift */,
 				690FF0F42AF0F06100A0B06B /* PostHogSDKTest.swift */,
+				699C5FEE2C20242A007DB818 /* UUIDTest.swift */,
 			);
 			path = PostHogTests;
 			sourceTree = "<group>";
@@ -1081,6 +1090,8 @@
 				69EE82BA2BA9C50400EB9542 /* PostHogReplayIntegration.swift in Sources */,
 				3AE3FB472992AB0000AFFC18 /* Hedgelog.swift in Sources */,
 				69261D132AD5685B00232EC7 /* PostHogFeatureFlags.swift in Sources */,
+				699C5FE62C20178E007DB818 /* UUIDUtils.swift in Sources */,
+				690B2DF32C205B5600AE3B45 /* TimeBasedEpochGenerator.swift in Sources */,
 				69261D1D2AD967CD00232EC7 /* PostHogFileBackedQueue.swift in Sources */,
 				3AE3FB432992985A00AFFC18 /* Reachability.swift in Sources */,
 				69F518122BAC783300F52C14 /* CGColor+Util.swift in Sources */,
@@ -1094,6 +1105,7 @@
 				690FF0F52AF0F06100A0B06B /* PostHogSDKTest.swift in Sources */,
 				690FF0E12AEFC59100A0B06B /* PostHogFileBackedQueueTest.swift in Sources */,
 				3A62647529CB0168007E8C07 /* TestPostHog.swift in Sources */,
+				699C5FEF2C20242A007DB818 /* UUIDTest.swift in Sources */,
 				3A62646A29C9E385007E8C07 /* MockPostHogServer.swift in Sources */,
 				690FF0BB2AEF8B8200A0B06B /* PostHogContextTest.swift in Sources */,
 				690FF0E32AEFD12900A0B06B /* PostHogConfigTest.swift in Sources */,

PostHog/Models/PostHogEvent.swift

@@ -25,7 +25,7 @@ public class PostHogEvent {
         case apiKey
     }
 
-    init(event: String, distinctId: String, properties: [String: Any]? = nil, timestamp: Date = Date(), uuid: UUID = .init(), apiKey: String? = nil) {
+    init(event: String, distinctId: String, properties: [String: Any]? = nil, timestamp: Date = Date(), uuid: UUID = UUID.v7(), apiKey: String? = nil) {
         self.event = event
         self.distinctId = distinctId
         self.properties = properties ?? [:]
@@ -61,8 +61,8 @@ public class PostHogEvent {
 
         guard let distinctId = (json["distinct_id"] as? String) ?? (properties["distinct_id"] as? String) else { return nil }
 
-        let uuid = ((json["uuid"] as? String) ?? (json["message_id"] as? String)) ?? UUID().uuidString
-        let uuidObj = UUID(uuidString: uuid) ?? UUID()
+        let uuid = ((json["uuid"] as? String) ?? (json["message_id"] as? String)) ?? UUID.v7().uuidString
+        let uuidObj = UUID(uuidString: uuid) ?? UUID.v7()
 
         let apiKey = json["api_key"] as? String
 

PostHog/PostHogSDK.swift

@@ -733,7 +733,7 @@ private let sessionChangeThreshold: TimeInterval = 60 * 30
     }
 
     private func rotateSession() {
-        let newSessionId = UUID().uuidString
+        let newSessionId = UUID.v7().uuidString
         let newSessionLastTimestamp = now().timeIntervalSince1970
 
         sessionLock.withLock {

PostHog/PostHogSessionManager.swift

@@ -25,7 +25,8 @@ class PostHogSessionManager {
             anonymousId = storage.getString(forKey: .anonymousId)
 
             if anonymousId == nil {
-                anonymousId = idGen(UUID()).uuidString
+                let uuid = UUID.v7()
+                anonymousId = idGen(uuid).uuidString
                 setAnonId(anonymousId ?? "")
             }
         }

PostHog/Utils/TimeBasedEpochGenerator.swift

@@ -0,0 +1,86 @@
+//
+//  TimeBasedEpochGenerator.swift
+//  PostHog
+//
+//  Created by Manoel Aranda Neto on 17.06.24.
+//
+
+import Foundation
+
+class TimeBasedEpochGenerator {
+    static let shared = TimeBasedEpochGenerator()
+
+    // Private initializer to prevent multiple instances
+    private init() {}
+
+    private var lastEntropy = [UInt8](repeating: 0, count: 10)
+    private var lastTimestamp: UInt64 = 0
+
+    private let lock = NSLock()
+
+    func v7() -> UUID {
+        var uuid: UUID?
+
+        lock.withLock {
+            uuid = generateUUID()
+        }
+
+        // or fallback to UUID v4
+        return uuid ?? UUID()
+    }
+
+    private func generateUUID() -> UUID? {
+        let timestamp = Date().timeIntervalSince1970
+        let unixTimeMilliseconds = UInt64(timestamp * 1000)
+
+        var uuidBytes = [UInt8]()
+
+        let timeBytes = unixTimeMilliseconds.bigEndianData.suffix(6) // First 6 bytes for the timestamp
+        uuidBytes.append(contentsOf: timeBytes)
+
+        if unixTimeMilliseconds == lastTimestamp {
+            var check = true
+            for index in (0 ..< 10).reversed() where check {
+                var temp = lastEntropy[index]
+                temp = temp &+ 0x01
+                check = lastEntropy[index] == 0xFF
+                lastEntropy[index] = temp
+            }
+        } else {
+            lastTimestamp = unixTimeMilliseconds
+
+            // Prepare the random part (10 bytes to complete the UUID)
+            let status = SecRandomCopyBytes(kSecRandomDefault, lastEntropy.count, &lastEntropy)
+            // If we can't generate secure random bytes, use a fallback
+            if status != errSecSuccess {
+                let randomData = (0 ..< 10).map { _ in UInt8.random(in: 0 ... 255) }
+                lastEntropy = randomData
+            }
+        }
+        uuidBytes.append(contentsOf: lastEntropy)
+
+        // Set version (7) in the version byte
+        uuidBytes[6] = (uuidBytes[6] & 0x0F) | 0x70
+
+        // Set the UUID variant (10xx for standard UUIDs)
+        uuidBytes[8] = (uuidBytes[8] & 0x3F) | 0x80
+
+        // Ensure we have a total of 16 bytes
+        if uuidBytes.count == 16 {
+            return UUID(uuid: (uuidBytes[0], uuidBytes[1], uuidBytes[2], uuidBytes[3],
+                               uuidBytes[4], uuidBytes[5], uuidBytes[6], uuidBytes[7],
+                               uuidBytes[8], uuidBytes[9], uuidBytes[10], uuidBytes[11],
+                               uuidBytes[12], uuidBytes[13], uuidBytes[14], uuidBytes[15]))
+        }
+
+        return nil
+    }
+}
+
+extension UInt64 {
+    // Correctly generate Data representation in big endian format
+    var bigEndianData: Data {
+        var bigEndianValue = bigEndian
+        return Data(bytes: &bigEndianValue, count: MemoryLayout<UInt64>.size)
+    }
+}

PostHog/Utils/UUIDUtils.swift

@@ -0,0 +1,17 @@
+//
+//  UUIDUtils.swift
+//  PostHog
+//
+//  Created by Manoel Aranda Neto on 17.06.24.
+//
+
+// Inspired and adapted from https://github.com/nthState/UUIDV7/blob/main/Sources/UUIDV7/UUIDV7.swift
+// but using SecRandomCopyBytes
+
+import Foundation
+
+public extension UUID {
+    static func v7() -> Self {
+        TimeBasedEpochGenerator.shared.v7()
+    }
+}

PostHogTests/PostHogSessionManagerTest.swift

@@ -35,7 +35,7 @@ class PostHogSessionManagerTest: QuickSpec {
             let distinctId = sut.getDistinctId()
             expect(distinctId) == anonymousId
 
-            let idToSet = UUID().uuidString
+            let idToSet = UUID.v7().uuidString
             sut.setDistinctId(idToSet)
             let newAnonymousId = sut.getAnonymousId()
             let newDistinctId = sut.getDistinctId()
@@ -48,7 +48,7 @@ class PostHogSessionManagerTest: QuickSpec {
 
         it("Can can accept id customization via config") {
             let config = PostHogConfig(apiKey: "123")
-            let fixedUuid = UUID()
+            let fixedUuid = UUID.v7()
             config.getAnonymousId = { _ in fixedUuid }
             let sut = PostHogSessionManager(config)
             let anonymousId = sut.getAnonymousId()

PostHogTests/UUIDTest.swift

@@ -0,0 +1,101 @@
+//
+//  UUIDTest.swift
+//  PostHogTests
+//
+//  Created by Manoel Aranda Neto on 17.06.24.
+//
+
+import Foundation
+
+import Foundation
+import Nimble
+@testable import PostHog
+import Quick
+
+class UUIDTest: QuickSpec {
+    private func compareULongs(_ l1: UInt64, _ l2: UInt64) -> Int {
+        let high1 = Int32(bitPattern: UInt32((l1 >> 32) & 0xFFFF_FFFF))
+        let high2 = Int32(bitPattern: UInt32((l2 >> 32) & 0xFFFF_FFFF))
+        var diff = compareUInts(high1, high2)
+        if diff == 0 {
+            let low1 = Int32(bitPattern: UInt32(l1 & 0xFFFF_FFFF))
+            let low2 = Int32(bitPattern: UInt32(l2 & 0xFFFF_FFFF))
+            diff = compareUInts(low1, low2)
+        }
+        return diff
+    }
+
+    private func compareUInts(_ i1: Int32, _ i2: Int32) -> Int {
+        if i1 < 0 {
+            return Int(i2 < 0 ? (i1 - i2) : 1)
+        }
+        return Int(i2 < 0 ? -1 : (i1 - i2))
+    }
+
+    override func spec() {
+        it("mostSignificantBits") {
+            let uuid = UUID(uuidString: "019025e6-b135-7e40-97df-ae0cebef184c")!
+            expect(uuid.mostSignificantBits) == 112_631_663_430_041_152
+        }
+
+        it("leastSignificantBits") {
+            let uuid = UUID(uuidString: "019025e6-b135-7e40-97df-ae0cebef184c")!
+            expect(uuid.leastSignificantBits) == -7_503_087_083_654_801_332
+        }
+
+        it("test sorted and duplicated") {
+            let count = 10000
+
+            var created: [UUID] = []
+            for _ in 0 ..< count {
+                created.append(UUID.v7())
+            }
+
+            let sortedUUIDs = created.sorted { uuid1, uuid2 in
+                if uuid1.mostSignificantBits != uuid2.mostSignificantBits {
+                    return uuid1.mostSignificantBits < uuid2.mostSignificantBits
+                }
+                return uuid1.leastSignificantBits < uuid2.leastSignificantBits
+            }
+
+            var unique: Set<UUID> = Set(minimumCapacity: count)
+
+            for i in 0 ..< created.count {
+                expect(sortedUUIDs[i]) == created[i]
+                if !unique.insert(created[i]).inserted {
+                    fatalError("Duplicate at index \(i)")
+                }
+            }
+        }
+    }
+}
+
+extension UUID {
+    var mostSignificantBits: Int64 {
+        let uuidBytes = withUnsafePointer(to: uuid) {
+            $0.withMemoryRebound(to: UInt8.self, capacity: 16) {
+                Array(UnsafeBufferPointer(start: $0, count: 16))
+            }
+        }
+
+        var mostSignificantBits: UInt64 = 0
+        for i in 0 ..< 8 {
+            mostSignificantBits = (mostSignificantBits << 8) | UInt64(uuidBytes[i])
+        }
+        return Int64(bitPattern: mostSignificantBits)
+    }
+
+    var leastSignificantBits: Int64 {
+        let uuidBytes = withUnsafePointer(to: uuid) {
+            $0.withMemoryRebound(to: UInt8.self, capacity: 16) {
+                Array(UnsafeBufferPointer(start: $0, count: 16))
+            }
+        }
+
+        var leastSignificantBits: UInt64 = 0
+        for i in 8 ..< 16 {
+            leastSignificantBits = (leastSignificantBits << 8) | UInt64(uuidBytes[i])
+        }
+        return Int64(bitPattern: leastSignificantBits)
+    }
+}