refactor: move request signing to Swift by nickolas-dimitrakas · Pull Request #872 · mParticle/mparticle-apple-sdk

nickolas-dimitrakas · 2026-08-27T20:48:02Z

The stack

refactor: move request signing to Swift #872 — request signing
refactor: move URL request header assembly to Swift #873 — URL request headers
refactor: move endpoint host resolution to Swift #874 — endpoint host resolution
test: pin the exact endpoint URL strings before converting them #875 — endpoint URL characterization tests
refactor: move endpoint path-style decisions to Swift #876 — endpoint path-style decisions

Review bottom-up; merge top-down. This is #872.

First of five. Stacked on #868 — base it on #868's head after that PR is rebased onto
workstation/swift-migration; it currently branches off #861 and is missing #862.

What moves

MPRequestSigner owns four things extracted from MPURLRequestBuilder:

the HMAC-SHA256 hex encode,
the METHOD\nDATE\npath[?query] signature shape (config, audience),
the METHOD\nDATE\npath<body> shape (identity, events),
and the 8192-character query cap.

hmacSha256Encode:key: keeps its selector as a one-line forward.
MPURLRequestBuilderTests.m calls it through a test-only category and remains the
behaviour contract.

Two ObjC quirks preserved on purpose

An embedded NUL truncates. The original ran both strings through
cStringUsingEncoding: + strlen, so anything after a NUL was never hashed. Swift
reproduces that by hashing only the bytes before the first NUL — bytesUpToFirstNUL.
A nil message or key yields nil, but an empty message still hashes.
testInvalidHMACSha256Encode pins both halves.

The query cap counts UTF-16 units to match NSString.length, not Swift's grapheme count.

CommonCrypto → CryptoKit

Both are system libraries, so no podspec or Package.swift change. Output is
byte-identical, verified against the existing ObjC reference vector plus a new
openssl-derived one in the Swift mirror test.

Gate

Item	Result
1. Zero public-ABI diff	pass — `abi-guard.sh check` clean, `Include/` diff empty
2. `pod lib lint` x3 podspecs	iOS pass ("passed validation"); tvOS not runnable locally
3. Build iOS + tvOS	iOS pass, no new warnings; tvOS not runnable locally
4. `trunk check`	pass — no new issues
5. ObjC + Swift suites	pass — ObjC 982/982, Swift 368/368 (14 new here)

MPURLRequestBuilder is not in mParticle-Apple-SDK/Include/, so it has no ABI baseline
entry.

tvOS is CI-only: this machine has the tvOS 26.2 SDK but only the 26.0 simulator
runtime, so no tvOS destination resolves and pod lint's tvOS leg fails the whole lint even
though iOS passes. Environmental, not a compile failure.

On the test suites: both suites flake under Xcode's default parallel testing on this
machine — MPUserDefaultsTests races on shared UserDefaults, and several slow ObjC
tests time out and force an xctest restart that prints "0 failures" while silently
skipping ~75 tests. Both reproduce on the unmodified base, so the counts above were taken
with -parallel-testing-enabled NO. Filed separately.

🤖 Generated with Claude Code

github-actions · 2026-08-27T20:48:29Z

🐦 Swift Migration Progress

Production implementation code at 0e50c4ced1ea compared with 502ba6d79e3e.

Area	Goal	Progress	Base	This PR	Swift SLOC	Objective-C remaining	Change
Core SDK	Short term — in scope	`████▎░░░░░`	41.60%	41.90%	6,072	8,418	🚀 +0.30 pp
Core SDK	Long term — all Objective-C	`███░░░░░░░`	29.62%	29.85%	6,072	14,273	🚀 +0.23 pp
SDK kit infrastructure	Short term — in scope	`░░░░░░░░░░`	0.00%	0.00%	0	3,340	➖ 0.00 pp
SDK kit infrastructure	Long term — all Objective-C	`░░░░░░░░░░`	0.00%	0.00%	0	3,725	➖ 0.00 pp
Standalone kits	Short term — in scope	`▏░░░░░░░░░`	1.06%	1.06%	152	14,231	➖ 0.00 pp
Standalone kits	Long term — all Objective-C	`▏░░░░░░░░░`	1.06%	1.06%	152	14,231	➖ 0.00 pp

Objective-C retained by design: Core SDK 5,855 · SDK kit infrastructure 385 · Standalone kits 0.

This PR's code movement

Area	Swift lines added	Objective-C lines removed
Core SDK	58	64
SDK kit infrastructure	0	0
Standalone kits	0	0

How this is measured

Current composition uses production source lines of code (SLOC) from cloc; comments and blank lines are excluded.
Short term — in scope excludes the Objective-C the migration will not delete, so 100% is the end of this project: every in-scope implementation gone.
Long term — all Objective-C keeps the full denominator. Reaching 100% there means the public API itself becomes Swift, which is a breaking change reserved for a future major release.
The gap between the two rows is the retained public/kit contract, runtime-identity, and boundary-glue surface listed in Tools/swift-migration-retained-objc.txt.
Retained wrappers keep their Objective-C interface but still shed logic to Swift. That thinning moves the long-term row and the retained figure, not the short-term row.
Both revisions are measured with the manifest from the head revision, so a manifest edit does not by itself move the reported change. A retained file this pull request renamed or deleted still counts as retained at the base.
Pull request movement uses physical additions/deletions from git diff base...head --numstat; it counts retained files too and is intentionally separate from SLOC totals.
Core excludes SDK kit infrastructure and vendored libraries. Standalone kits include only files below Kits/**/Sources.
Tests, examples, headers, build outputs, vendored libraries, and the MParticle/Sources Swift overlay are excluded.
Objective-C++ (.mm) is included in the Objective-C figures and removed counts.

Generated with cloc 2.10. This report is informational and does not gate migration direction.

github-actions · 2026-08-27T20:50:57Z

📦 SDK Size Impact Report

Measures how much the SDK adds to an app's size (with-SDK minus without-SDK).

Metric	Target Branch	This PR	Change
App Bundle Impact	2.16 MB	2.16 MB	+4 KB
Executable Impact	848 bytes	848 bytes	+N/A
XCFramework Size	6.66 MB	6.67 MB	+4 KB

➡️ SDK size impact change is minimal.

Raw measurements

Target branch (workstation/swift-migration):

{"baseline_app_size_kb":84,"baseline_executable_size_bytes":75464,"with_sdk_app_size_kb":2292,"with_sdk_executable_size_bytes":76312,"sdk_impact_kb":2208,"sdk_executable_impact_bytes":848,"xcframework_size_kb":6824}

This PR:

{"baseline_app_size_kb":84,"baseline_executable_size_bytes":75464,"with_sdk_app_size_kb":2296,"with_sdk_executable_size_bytes":76312,"sdk_impact_kb":2212,"sdk_executable_impact_bytes":848,"xcframework_size_kb":6828}

cursor · 2026-09-01T14:17:18Z

PR Summary

Medium Risk
Changes how x-mp-signature is computed for config, audience, identity, and events; parity tests mitigate risk but any subtle crypto or string-format drift would break authenticated API calls.

Overview
Extracts HTTP request signing from MPURLRequestBuilder into a new ObjC-exposed Swift type, MPRequestSigner, as the first step in the network Swift migration.

MPURLRequestBuilder no longer uses CommonCrypto inline for HMAC or hand-built signature strings. It imports the Swift module and delegates HMAC-SHA256 hex, canonical signature message formatting (METHOD\nDATE\npath[?query] vs METHOD\nDATE\npath<body>), and the 8192 UTF-16-unit query limit to MPRequestSigner. The private hmacSha256Encode:key: wrapper remains a one-line forward.

MPRequestSigner implements HMAC with CryptoKit and deliberately preserves legacy ObjC behavior: nil message or key → nil HMAC, embedded NUL truncates inputs before hashing, and empty query still uses ?. New MPRequestSignerTests lock these rules plus a reference HMAC vector; existing MPURLRequestBuilderTests stay the integration contract.

^{Reviewed by Cursor Bugbot for commit 0e50c4c. Bugbot is set up for automated code reviews on this repo. Configure here.}

Extracts HMAC-SHA256 encoding and signature-message assembly from MPURLRequestBuilder into a Foundation-only Swift type, per docs/swift-migration/CONVERSION-RECIPE.md. MPRequestSigner owns four things: the HMAC hex encode, the two signature-message shapes (path + "?" + query for config and audience, path + body for identity and events), and the 8192-character query cap. The .m still owns NSMutableURLRequest, the cache policy, the timeout, every header assignment, and its MPILogError calls -- it resolves the state machine, kit container, web view and user defaults into plain values before calling Swift, because mParticle-Apple-SDK-Swift cannot import the ObjC module. hmacSha256Encode:key: keeps its selector as a one-line forward. MPURLRequestBuilderTests.m calls it through a test-only category, and it stays the behaviour contract. Two ObjC behaviours are preserved deliberately and covered by tests: - The original passed the strings through cStringUsingEncoding: and strlen, so an embedded NUL truncates the message or the key. Swift reproduces that by hashing only the bytes before the first NUL. - A nil message or key yields nil, but an empty message still hashes. MPURLRequestBuilderTests testInvalidHMACSha256Encode pins both. The query cap counts UTF-16 units, matching NSString.length rather than Swift's grapheme count. Signing switches from CommonCrypto to CryptoKit. Both are system libraries, so no podspec or Package.swift change is needed, and the output is byte-identical -- verified against the existing ObjC reference vector plus a new openssl-derived one in the Swift mirror test. MPURLRequestBuilder is not in mParticle-Apple-SDK/Include/, so it has no ABI baseline entry; Include/ has a zero diff and abi-guard.sh check passes. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

nickolas-dimitrakas self-assigned this Aug 27, 2026

Base automatically changed from feat/BWS-Swift-Migration-9 to workstation/swift-migration August 31, 2026 18:01

nickolas-dimitrakas force-pushed the refactor/request-signing-to-swift branch from 1832cb7 to 4ebab21 Compare August 31, 2026 20:37

nickolas-dimitrakas marked this pull request as ready for review September 1, 2026 14:17

nickolas-dimitrakas requested a review from a team as a code owner September 1, 2026 14:17

nickolas-dimitrakas force-pushed the refactor/request-signing-to-swift branch from 4ebab21 to 0e50c4c Compare September 1, 2026 15:00

BrandonStalnaker approved these changes Sep 1, 2026

View reviewed changes

nickolas-dimitrakas merged commit 95f8700 into workstation/swift-migration Sep 1, 2026
79 of 80 checks passed

nickolas-dimitrakas deleted the refactor/request-signing-to-swift branch September 1, 2026 15:07

Navigation Menu

refactor: move request signing to Swift - #872

refactor: move request signing to Swift#872
nickolas-dimitrakas merged 1 commit into
workstation/swift-migrationfrom
refactor/request-signing-to-swift

nickolas-dimitrakas commented Aug 27, 2026 •

edited

Loading

Uh oh!

github-actions Bot commented Aug 27, 2026 •

edited

Loading

Uh oh!

github-actions Bot commented Aug 27, 2026 •

edited

Loading

Uh oh!

cursor Bot commented Sep 1, 2026 •

edited

Loading

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Conversation

nickolas-dimitrakas commented Aug 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

The stack

What moves

Two ObjC quirks preserved on purpose

CommonCrypto → CryptoKit

Gate

Uh oh!

github-actions Bot commented Aug 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

🐦 Swift Migration Progress

This PR's code movement

Uh oh!

github-actions Bot commented Aug 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

📦 SDK Size Impact Report

Uh oh!

cursor Bot commented Sep 1, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

PR Summary

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

nickolas-dimitrakas commented Aug 27, 2026 •

edited

Loading

github-actions Bot commented Aug 27, 2026 •

edited

Loading

github-actions Bot commented Aug 27, 2026 •

edited

Loading

cursor Bot commented Sep 1, 2026 •

edited

Loading