Merged PR 414899: MSLabel and MSButton should respect "adjustFontForContentSizeCategory" property

Currently, both MSLabel and MSButton listen to content size category change notification, and update its font size accordingly. We should follow the iOS native behavior that only when "adjustFontForContentSizeCategory" is true, we should update dynamically update the font size. iOS default for adjustFontForContentSizeCategory is set to false, but for MSLabel and MSButton we will set it to true..

Button, label, cell demo in various accessibility text sizes

Author: harrieshin

OfficeUIFabric.Demo/OfficeUIFabric.Demo/Demos/ObjectiveCDemoController.m

@@ -36,6 +36,9 @@ - (void)viewDidLoad {
         [[self.container leftAnchor] constraintEqualToAnchor:[self.scrollingContainer leftAnchor]],
         [[self.container widthAnchor] constraintEqualToAnchor:[self.scrollingContainer widthAnchor]],
     ]];
+
+    MSButton *testButton = [self createButtonWithTitle:@"Test" action:nil];
+    [self.container addArrangedSubview:testButton];
 }
 
 - (UIStackView *)createVerticalContainer {

OfficeUIFabric/Controls/MSButton.swift

@@ -48,6 +48,7 @@ import UIKit
 
 // MARK: - MSButton
 
+/// By default, `titleLabel`'s `adjustsFontForContentSizeCategory` is set to true to automatically update its font when device's content size category changes
 @IBDesignable
 open class MSButton: UIButton {
     private struct Constants {
@@ -119,9 +120,8 @@ open class MSButton: UIButton {
         }
 
         titleLabel?.font = Constants.titleFont
+        titleLabel?.adjustsFontForContentSizeCategory = true
         update()
-
-        NotificationCenter.default.addObserver(self, selector: #selector(handleContentSizeCategoryDidChange), name: UIContentSizeCategory.didChangeNotification, object: nil)
     }
 
     open override func layoutSubviews() {
@@ -159,8 +159,4 @@ open class MSButton: UIButton {
 
         contentEdgeInsets = style.contentEdgeInsets
     }
-
-    @objc private func handleContentSizeCategoryDidChange() {
-        update()
-    }
 }

OfficeUIFabric/Controls/MSLabel.swift

@@ -5,6 +5,7 @@
 
 import UIKit
 
+/// By default, `adjustsFontForContentSizeCategory` is set to true to automatically update its font when device's content size category changes
 open class MSLabel: UILabel {
     @objc open var colorStyle: MSTextColorStyle = .regular {
         didSet {
@@ -55,6 +56,7 @@ open class MSLabel: UILabel {
 
         updateFont()
         updateTextColor()
+        adjustsFontForContentSizeCategory = true
 
         NotificationCenter.default.addObserver(self, selector: #selector(handleContentSizeCategoryDidChange), name: UIContentSizeCategory.didChangeNotification, object: nil)
         if #available(iOS 13, *) { } else {
@@ -76,7 +78,9 @@ open class MSLabel: UILabel {
     }
 
     @objc private func handleContentSizeCategoryDidChange() {
-        updateFont()
+        if adjustsFontForContentSizeCategory {
+            updateFont()
+        }
     }
 
     @objc private func handleDarkerSystemColorsStatusDidChange() {