fix: TTFD waits for next drawn frame

[philipphofmann]

📜 Description

The SDK waits for the next drawn frame after users call reportFullyDisplayed to reflect when UI changes are visible to the user correctly.

💡 Motivation and Context

Preparation for #3471.

💚 How did you test it?

Unit tests and simulator.

📝 Checklist

You have to check all boxes before merging:

• I reviewed the submitted code.
• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.

🔮 Next steps

[codecov]

Codecov Report

Merging #3505 (e81bf86) into main (f0ce81c) will increase coverage by 0.006%.
The diff coverage is 100.000%.

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #3505       +/-   ##
=============================================
+ Coverage   89.197%   89.204%   +0.006%     
=============================================
  Files          528       528               
  Lines        57431     57466       +35     
  Branches     20572     20599       +27     
=============================================
+ Hits         51227     51262       +35     
- Misses        5291      5295        +4     
+ Partials       913       909        -4     

Files	Coverage Δ
Sources/Sentry/SentryTimeToDisplayTracker.m	100.000% <100.000%> (ø)
.../Sentry/SentryUIViewControllerPerformanceTracker.m	98.800% <100.000%> (ø)
...ce/SentryPerformanceTrackingIntegrationTests.swift	100.000% <ø> (ø)
...iewController/SentryTimeToDisplayTrackerTest.swift	99.618% <100.000%> (+1.642%)	⬆️
...entryUIViewControllerPerformanceTrackerTests.swift	97.274% <100.000%> (+0.210%)	⬆️

... and 15 files with indirect coverage changes

---

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[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1197.37 ms	1215.67 ms	18.31 ms
Size	21.58 KiB	418.33 KiB	396.75 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
45d3ca5	1248.27 ms	1255.48 ms	7.21 ms
1437c68	1244.86 ms	1254.18 ms	9.32 ms
db31083	1252.52 ms	1266.65 ms	14.13 ms
32c4446	1225.00 ms	1231.29 ms	6.29 ms
7bb0873	1360.94 ms	1362.24 ms	1.30 ms
ad7cec6	1203.22 ms	1224.74 ms	21.52 ms
ff09c7e	1240.94 ms	1262.66 ms	21.72 ms
a176fc4	1239.78 ms	1258.98 ms	19.20 ms
3277f18	1229.29 ms	1248.92 ms	19.63 ms
8f397a7	1251.82 ms	1268.34 ms	16.52 ms

App size

Revision	Plain	With Sentry	Diff
45d3ca5	20.76 KiB	427.54 KiB	406.78 KiB
1437c68	22.85 KiB	410.96 KiB	388.11 KiB
db31083	22.85 KiB	407.62 KiB	384.77 KiB
32c4446	22.84 KiB	403.24 KiB	380.39 KiB
7bb0873	22.85 KiB	407.09 KiB	384.24 KiB
ad7cec6	20.76 KiB	427.32 KiB	406.55 KiB
ff09c7e	20.76 KiB	427.76 KiB	407.00 KiB
a176fc4	22.84 KiB	403.24 KiB	380.39 KiB
3277f18	22.84 KiB	402.88 KiB	380.03 KiB
8f397a7	20.76 KiB	420.55 KiB	399.79 KiB

Previous results on branch: fix/ttfd-wait-frame

Startup times

Revision	Plain	With Sentry	Diff
dcef2fe	1239.04 ms	1252.16 ms	13.12 ms

App size

Revision	Plain	With Sentry	Diff
dcef2fe	21.58 KiB	418.48 KiB	396.90 KiB

[brustolin]

The SDK waits for the next drawn frame after users call reportFullyDisplayed to reflect when UI changes are visible to the user correctly. As this change is a breaking change, this fix only works when enabling performance V2

This was always the intention, if its not working properly, I don't think is a breaking change fixing it. I prefer to not add this V2 thing.

[philipphofmann]

Okay, I didn't know it was the intention. We will add the V2 option, but it's better if we use it sparingly. I will update the PR.

[brustolin]

LGTM