Fix Picker layout on Mac Catalyst 26+

[kubaflo]

On Mac Catalyst 26+, the Picker view was incorrectly positioned, appearing visually shifted within the picker controller.
This PR centers UIPickerView using NSLayoutConstraint when added to the pickerController’s view. This ensures correct alignment, predictable sizing, and consistent layout behavior across Mac Catalyst versions.

Fixes #33229

Before	After

[dotnet-policy-service]

Hey there @@kubaflo! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[Copilot]

Pull request overview

This PR fixes a layout issue with the Picker view on Mac Catalyst 26+ where the UIPickerView was incorrectly positioned within the picker controller. The fix centers the UIPickerView using NSLayoutConstraint instead of relying solely on frame-based layout, ensuring correct alignment and consistent behavior across Mac Catalyst versions.

Key Changes:

• Replaces frame-based layout with Auto Layout constraints for UIPickerView positioning
• Ensures the picker view is centered horizontally and properly sized within the alert controller
• Maintains backward compatibility while fixing the layout issue on Mac Catalyst 26+

[PureWeen]

Build issue: pickerController on line 87 should be _pickerController (missing underscore). There is no local variable named pickerController in this method — only the field _pickerController. This will fail to compile on MacCatalyst.

Minor suggestion: Since the new constraints fully define the picker's layout, the initial frame passed to new UIPickerView(frame) on line 53 is now effectively ignored. Consider simplifying to new UIPickerView() to make it clear constraints drive the layout.

[kubaflo]

🤖 AI Summary

📊 Expand Full Review

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🔍 Pre-Flight — Context & Validation

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📝 Review Session — Remove explicit frame use for UIPickerView · 7ce058a

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Issue: #33229 - [MacOS 26] Text on picker options are not centered on macOS 26.1
PR: #33146 - Fix Picker layout on Mac Catalyst 26+
Author: kubaflo
Platforms Affected: Mac Catalyst (macOS 26+ / iOS 26 SDK), labeled platform/macos, version/iOS-26
Milestone: .NET 10 SR5

Summary

On Mac Catalyst 26+, the UIPickerView inside the UIAlertController used for the Mac Catalyst Picker implementation was incorrectly positioned. The old code used frame-based layout with a hardcoded x=0 and width=269, causing the picker to appear left-aligned when the alert controller's view was wider. The fix replaces frame-based positioning with Auto Layout (NSLayoutConstraint) to properly center and size the picker.

Files Changed

File	Type	Changes
src/Core/src/Handlers/Picker/PickerHandler.iOS.cs	Fix	+12, -3

No test files changed.

Key Technical Changes

1. Removed using RectangleF = CoreGraphics.CGRect; alias (no longer needed)
   new UIPickerView() (no frame)
2. Added TranslatesAutoresizingMaskIntoConstraints = false
3. Added NSLayoutConstraint array: CenterX, Width (container), Top (paddingTitle offset), Height (240)

Reviewer Feedback

Reviewer	Commit	Feedback	Status
copilot-pull-request-reviewer[bot]	f718cd0	COMMENTED: Overview of fix, no blockers	Informational
build failure; (2) Suggest new UIPickerView()	Addressed in latest commit

Note: PureWeen's review was on commit 81abfc96. Current HEAD is 7ce058a0. Both concerns have been addressed: _pickerController is used correctly, and new UIPickerView() is used without frame. PureWeen has not re-reviewed after the fix.

Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
PR	PR #33146	Replace frame-based UIPickerView layout with NSLayoutConstraint (CenterX, Width=container, Top=paddingTitle, Height= PENDING (Gate)	PickerHandler.iOS.cs (+12)	Original PR; addresses Mac Catalyst 26+ positioning regression	240)

Edge Cases Noted

• Fix uses WidthAnchor.ConstraintEqualTo(container. makes picker full container width. This changes behavior on ALL Mac Catalyst versions, not just 26+. On macOS 15, old code worked (269px width, x=0). Need to verify regression risk on older Mac Catalyst.WidthAnchor)
• No automated tests included in PR.

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🚦 Gate — Test Verification

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📝 Review Session — Remove explicit frame use for UIPickerView · 7ce058a

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** FAILED - No automated tests exist for this issueResult:**
Platform Requested: ios (user-specified)
Actual Affected Platform: Mac Catalyst (macOS #if MACCATALYST code path26+)
Mode: N/ Could not runA

Gate Failure Reason

No automated tests exist for Issue #33229. The PR does not include any test files:

gh pr view 33146 --json files --jq '.files[].path' | grep -E "TestCases|UnitTests|DeviceTests"
 (no output)

• No issue-specific test in TestCases.HostApp/Issues/
• No NUnit test in TestCases.Shared.Tests/Tests/Issues/
• No snapshot test added to TestCases.Mac.Tests/

Platform Mismatch

User requested ios platform, but the bug lives entirely in the #if MACCATALYST code block in PickerHandler.iOS.cs. Tests run on iOS simulators would not exercise this code path. Correct platform would be maccatalyst.

Autonomous Decision

Per SHARED-RULES.md autonomous execution guidance:
Document as FAILED, proceed to Report

• Try-fix phase: SKIPPED (Gate did not pass; no test baseline exists to verify fix)

Tests Needed

To properly validate this fix, a UI test should be written:

• HostApp page: Open the Picker on Mac Catalyst, verify picker options are centered
• Test: Take screenshot of open picker on Mac Catalyst 26+, compare against baseline
• Suggested tool: Use write-tests-agent to create Issue33229 test

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🔧 Fix — Analysis & Comparison

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📝 Review Session — Remove explicit frame use for UIPickerView · 7ce058a

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Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
PR	PR #33146	Replace frame-based UIPickerView layout with PENDING (Gate not passed)	PickerHandler.iOS.cs (+12)	Original PR	NSLayoutConstraint

Exhausted: SKIPPED (Gate did not pass; no tests exist to validate any fix)No

Selected Fix: PR's fix (by only candidate reviewed; no empirical try-fix possible without tests)default

Skip Reason

Try-fix phase was skipped because Gate did not pass. Gate requires automated tests to:

1. Verify tests FAIL without the fix
2. Verify tests PASS with the fix

Without tests, try-fix cannot empirically validate any fix candidate. All 5 model invocations were skipped.

Code Review Assessment of PR Fix

Despite not being able to run try-fix empirically, a code review assessment of the PR's fix:

Correct approach: Auto Layout (NSLayoutConstraint) is the right solution for Mac Catalyst 26+ where frame-based layout behavior changed.

Constraints added:

Potential concern: Width = container width changes behavior on all Mac Catalyst versions (not just 26+). On macOS 15, the old 269pt hardcoded width worked. The container width may differ. However, filling the container width is generally correct Auto Layout behavior.

PureWeen's feedback addressed:

• _pickerController (with underscore) used correctly in latest commit
• new UIPickerView() (without frame) used in latest commit

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📋 Report — Final Recommendation

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📝 Review Session — Remove explicit frame use for UIPickerView · 7ce058a

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Final Recommendation: REQUEST CHANGES##

Summary

PR #33146 fixes a real regression in the Mac Catalyst Picker where UIPickerView options appeared left-aligned (not centered) on macOS 26+. The fix replaces a hardcoded frame-based layout (x=0, width=269) with NSLayoutConstraint-based Auto Layout, which correctly centers and sizes the picker within the alert controller's view.

The fix is technically sound and addresses PureWeen's prior review feedback (build-breaking missing underscore on _pickerController, and the unused frame constructor). However, the PR is missing automated a notable gap for a regression fix on a platform-specific code path.tests

Root Cause

On Mac Catalyst 26+, the UIAlertController view geometry changed, making the hardcoded CGRect(x: 0, paddingTitle, width: 269, height: 240) no longer produce a centered layout. When the alert container grew wider, the picker stayed at x=0 and appeared left-aligned.

Fix Quality Assessment

Aspect	Assessment
Fix approach (Auto Layout NSLayoutConstraint is the right solution for Mac Catalyst 26+	Correct )
PureWeens blockers addressed Both build issue and simplification suggestion fixed
Constraint correctness Fully defines position + size (CenterX, Width, Top, Height)
Backward Changes behavior on all Mac Catalyst versions, not just 26+ (see below)	compatibility
Test No automated regression has no safety net	tests coverage

Platform Scope Note

The constraints change behavior on all Mac Catalyst (not just 26+). Previously on macOS 15, the 269pt wide picker worked. Now the picker fills the container width. This should be fine (full width is better than arbitrary 269pt) but it's an untested behavior change on older Mac Catalyst.

Reviewer Feedback Status

Reviewer	Status	Details
_pickerController) + simplification (new UIPickerView())
Latest commit	Addressed	Both concerns fixed in commit ` re-review needed from PureWeen

Request Changes Rationale

1. Missing Regression fix with no automated test coverage. If Mac Catalyst layout behavior changes again, there's nothing to catch it. A UI test or snapshot test should be added.tests
2. PureWeen's CHANGES_REQUESTED not The technical issues were fixed, but PureWeen hasn't re-reviewed. The PR needs a fresh approval after the fixes.dismissed
3. PR description missing NOTE Required by repository template.block

Suggested PR Title Update

Current: Fix Picker layout on Mac Catalyst 26+
Suggested: [MacCatalyst] Picker: Fix UIPickerView centering on macOS 26+

Gate Result

No automated tests exist for Issue #33229. Tests could not be run.FAILED

Try-Fix

Gate did not pass. No test baseline for empirical validation.SKIPPED

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📋 Expand PR Finalization Review

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Title: ✅ Good

Current: Fix Picker layout on Mac Catalyst 26+

Description: ✅ Good

Description needs updates. See details below.

✨ Suggested PR Description

[!NOTE]
Are you waiting for the changes in this PR to be merged?
It would be very helpful if you could test the resulting artifacts from this PR and let us know in a comment if this change resolves your issue. Thank you!

Root Cause

On Mac Catalyst 26+, the UIAlertController's container view dimensions changed such that a UIPickerView initialized with a hardcoded frame (x=0, y=paddingTitle, width=269, height=240) appeared left-aligned instead of centered. The fixed x=0 origin and width=269 no longer matched the wider alert controller container geometry introduced in macOS 26.

Description of Change

Replaced frame-based UIPickerView initialization with frameless construction (new UIPickerView()) and explicit NSLayoutConstraint Auto Layout constraints:

• CenterX aligned to the picker controller's view center
• Width equal to the full container width (replaces hardcoded 269px)
• Top offset by paddingTitle from the container top (preserves title padding behavior)
• Height set to 240pt

Also removed the now-unused using RectangleF = CoreGraphics.CGRect; alias.

All changes are scoped to the #if MACCATALYST code no impact on iOS behavior.path

Before / After

Before	After

Issues Fixed

Fixes #33229

Code Review: ✅ Passed

Code PR #33146Review

File reviewed: src/Core/src/Handlers/Picker/PickerHandler.iOS.cs
no iOS impact.

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Looks Good

• TranslatesAutoresizingMaskIntoConstraints = false is correctly set before activating required when mixing AddSubview with Auto Layout.constraints
• UIPickerView() (no-frame init) is the correct approach when Auto Layout will drive the layout.
• Constraints fully define position and no ambiguous layout:size
  • Horizontal: CenterXAnchor + WidthAnchor (over-constrained but not conflicting)
  • Vertical: TopAnchor offset + HeightAnchor
• paddingTitle correctly preserved as the TopAnchor offset maintains title padding behavior.constant
• pickerHeight (240) correctly reused for both the view's HeightAnchor constraint and the existing container height constraint below.
• using RectangleF = CoreGraphics.CGRect; alias correctly it was only used for the old frame constructor.removed
• Width change from hardcoded 269px to container.WidthAnchor is picker now adapts to the container, which is the correct behavior.appropriate

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1. Trailing whitespace

Line: immediately after _pickerController.View.AddSubview(pickerView);

The diff shows a blank line with trailing tab whitespace (\t\t\t\t\t). This is cosmetic but may fail the repo's formatting lint check.

Recommendation: Remove the trailing whitespace from that blank line.

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2. Redundant null-conditional operator

Line:

pickerView?.ReloadAllComponents();

pickerView was assigned two lines earlier as new UIPickerView() and cannot be null at this point. The ?. is unnecessary.

Recommendation: Change to pickerView.ReloadAllComponents(); for clarity. (The ?. appeared in the original code before the fix when pickerView might have been nullable, but now it's always non-null here.)

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3. Constraint API inconsistency (pre-existing)

The new constraints use the modern NSLayoutConstraint.ActivateConstraints([...]) API, but the existing container height constraint below uses the older AddConstraint(height) pattern. The PR doesn't need to fix pre-existing code, but this is worth noting for future cleanup.

4. No automated test coverage

The fix addresses a visual regression (picker options not centered on Mac Catalyst 26+) with no accompanying automated test. UI tests for Mac Catalyst Picker centering would help prevent regressions. This is a gap, not a blocker, as visual layout issues are difficult to test automatically.

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Overall Verdict

The fix is technically correct. Auto Layout constraints are the right approach for Mac Catalyst 26+ where frame-based layout behavior changed. The two minor issues (trailing whitespace, redundant null-conditional) are cosmetic and non-blocking.

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