I'm adapting modal sheet presentation for iPhone Duo. My root is a UITabBarController, and I present detail view controllers with present(_:animated:) using .pageSheet / UISheetPresentationController. I want to confirm how much of the sheet's placement and sizing I can control as the device moves between poses, and which APIs are the intended levers versus behavior the system owns. 1. Closed pose — constraining sheet width away from the edges With modalPresentationStyle = .pageSheet in a horizontally compact layout, the sheet spans the full width. Is there a supported way to constrain its width so it doesn't run edge-to-edge — e.g. via the presented controller's preferredContentSize, a .formSheet style, or a custom UIPresentationController with an overridden frameOfPresentedViewInContainerView? Does UISheetPresentationController honor a preferred width, or is width strictly derived from the container's size class? 2. Partial open — targeting which arrangement the sheet presents over When the device is partially open and multiple arrangements are visible, can I influence which arrangement (leading vs. trailing) the sheet is presented in? Does the presentation container respect reserved regions and the current UIArrangement, and is there a recommended way to anchor a modal presentation to a specific arrangement — or is the presenting view controller's location in the hierarchy the only determinant? 3. Fully open — driving large vs. compact sheet sizing When fully unfolded with the additional horizontal space, is detents the correct mechanism to switch between a compact and expanded sheet (e.g. .medium(), .large(), or a .custom detent resolved via UISheetPresentationController.Detent.custom)? Should selectedDetentIdentifier be updated in response to trait changes, and is sheetPresentationController.widthFollowsPreferredContentSizeWhenEdgeAttached relevant here? General question: Should all of the above be driven by observing UITraitCollection changes (size classes) via traitCollectionDidChange(_:) / the trait registration APIs, or is there dedicated iPhone Duo API tied to the hinge angle and arrangements that I should adopt for sheet presentation instead?

When I tried this, the app crashed immediately with a requirement to use NSTextContentStorage subclass

I tried to download the beta and install to external SSD connected to M1 Mac mini. The installation continues until restart. The external drive cannot be used to boot up. SSD is erased and set to: APFS GUID Partition Map This strategy has been used in the last few years with Intel MacBook. I wonder if this is a problem with macOS or M1 machine?