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Author: kligarski

ios/RNSScreenStackHeaderSubview.mm

@@ -210,6 +210,10 @@ - (UIBarButtonItem *)getUIBarButtonItem
 {
   if (_barButtonItem == nil) {
 #if RNS_IPHONE_OS_VERSION_AVAILABLE(26_0)
+    // Starting from iOS 26, UIBarButtonItem's customView is streched to have at least 36 width.
+    // Stretching RNSScreenStackHeaderSubview means that its subviews are aligned to left instead
+    // of the center. To mitigate this, we add a wrapper view that will center
+    // RNSScreenStackHeaderSubview inside of itself.
     UIView *wrapperView = [UIView new];
     wrapperView.translatesAutoresizingMaskIntoConstraints = NO;
 
@@ -219,6 +223,10 @@ - (UIBarButtonItem *)getUIBarButtonItem
     [self.centerXAnchor constraintEqualToAnchor:wrapperView.centerXAnchor].active = YES;
     [self.centerYAnchor constraintEqualToAnchor:wrapperView.centerYAnchor].active = YES;
 
+    // To prevent UIKit from stretching subviews to all available width, we need to:
+    // 1. Set width of wrapperView to match RNSScreenStackHeaderSubview BUT when
+    //    RNSScreenStackHeaderSubview's width is smaller that minimal required 36 width, it breaks
+    //    UIKit's constraint. That's why we need to lower the priority of the constraint.
     NSLayoutConstraint *widthEqual = [wrapperView.widthAnchor constraintEqualToAnchor:self.widthAnchor];
     widthEqual.priority = UILayoutPriorityDefaultHigh;
     widthEqual.active = YES;
@@ -227,6 +235,7 @@ - (UIBarButtonItem *)getUIBarButtonItem
     heightEqual.priority = UILayoutPriorityDefaultHigh;
     heightEqual.active = YES;
 
+    // 2. Set content hugging prriority for RNSScreenStackHeaderSubview.
     [self setContentHuggingPriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisHorizontal];
     [self setContentHuggingPriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisVertical];