[SwiftUI] AvatarGroup SwiftUI API

[mischreiber]

Platforms Impacted

• iOS
• visionOS
• macOS

Description of changes

Creating a SwiftUI API for AvatarGroup.

Yes, it's always been a SwiftUI control, but the API was only ever designed to be used in a UIKit wrapper, where Avatar elements could be added and removed via event-driven method calls. Our new API is fully data-driven, as befits a native SwiftUI control.

let style = MSFAvatarGroupStyle.stack
let size = MSFAvatarSize.size40
let avatarCount = 5

// Basic initializer--there are more properties to explore!
AvatarGroup(style: style,
            size: size,
            avatarCount: avatarCount) { index in

    // Create and yield an Avatar for the given callback index.
    Avatar(style: style,
           size: size,
           image: fetchImage(index),
           primaryText: fetchName(index))
}

As part of this change, I've also avoided the ability to mark an AvatarGroup as transparent, aligning with our latest designs. This will eventually be deprecated across all existing Avatar endpoints.

Binary change

Total increase: 12,544 bytes
Total decrease: -52,432 bytes

File	Before	After	Delta
Total	31,203,440 bytes	31,163,552 bytes	🎉 -39,888 bytes

Full breakdown

File	Before	After	Delta
CalendarViewWeekdayHeadingView.o	77,928 bytes	83,480 bytes	⚠️ 5,552 bytes
SegmentedControl.o	330,216 bytes	333,640 bytes	⚠️ 3,424 bytes
PopupMenuController.o	375,464 bytes	378,064 bytes	⚠️ 2,600 bytes
MSFAvatarGroup.o	31,184 bytes	32,152 bytes	⚠️ 968 bytes
BottomSheetController.o	525,872 bytes	525,512 bytes	🎉 -360 bytes
MultilineCommandBar.o	140,104 bytes	139,352 bytes	🎉 -752 bytes
IndeterminateProgressBar.o	231,928 bytes	231,112 bytes	🎉 -816 bytes
HUD.o	267,176 bytes	266,200 bytes	🎉 -976 bytes
Avatar.o	604,704 bytes	596,968 bytes	🎉 -7,736 bytes
__.SYMDEF	4,863,752 bytes	4,855,520 bytes	🎉 -8,232 bytes
AvatarGroup.o	417,456 bytes	383,896 bytes	🎉 -33,560 bytes

Verification

Visual Verification

SwiftUI

AvatarGroupSwiftUI.mp4

UIKit

AvatarGroupUIKit.mp4

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