Activity Indicator: Remove branching of SwiftUI views to improve performance and readability

[imthath-m]

Platforms Impacted

• iOS
• macOS

Description of changes

Using conditional branching in SwiftUI views leads to performance issues as explained here in this WWDC video.

In ActivityIndicator, the View.modifyIf method is used multiple times which results in conditional branching of SwiftUI views. They cause performance issues and are not so easy to read. They can be easily avoided as shown in the changes.

Ideally, I would prefer that modifyIf extension is removed and condition branching of SwiftUI views is done explicitly so that developers can be easily made aware of its performance issues.

Binary change

Total increase: 0 bytes
Total decrease: -42,168 bytes

File	Before	After	Delta
Total	3,11,48,816 bytes	3,11,06,648 bytes	🎉 -42,168 bytes

Full breakdown

File	Before	After	Delta
__.SYMDEF	48,86,280 bytes	48,77,304 bytes	🎉 -8,976 bytes
SwiftUI+ViewModifiers.o	1,36,096 bytes	1,23,656 bytes	🎉 -12,440 bytes
ActivityIndicator.o	1,76,688 bytes	1,55,936 bytes	🎉 -20,752 bytes

Verification

Tested the demo app to ensure to no change in the ActivityIndicator's behaviour. It still appears and runs the same.

Visual Verification

Before	After
Screenshot or description before this change	Screenshot or description with this change

Pull request checklist

This PR has considered:

• Light and Dark appearances
• iOS supported versions (all major versions greater than or equal current target deployment version)
• VoiceOver and Keyboard Accessibility
• Internationalization and Right to Left layouts
• Different resolutions (1x, 2x, 3x)
• Size classes and window sizes (iPhone vs iPad, notched devices, multitasking, different window sizes, etc)
• iPad Pointer interaction
• SwiftUI consumption (validation or new demo scenarios needed)
• Objective-C exposure (provide it only if needed)

Microsoft Reviewers: Open in CodeFlow

[imthath-m]

@microsoft-github-policy-service agree

[mischreiber]

Looks like a clean upgrade, and my testing bears it out as well. Thanks!

[imthath-m]

Thanks for approving the changes.

Can you approve this workflow as well?