macOS Big Sur changes for developers

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Revision as of 20:31, 2 October 2020 by Jonas (talk | contribs) (ARM64/AArch64/AppleSilicon Support: Workaround for macOS bug)

This article applies to macOS only.

See also: Multiplatform Programming Guide

User interface changes

macOS 11 Big Sur introduces many user interface changes that update the appearance of applications and make them more iOS-like. It also adds support for familiar iOS features — such as SF Symbols and text styles.

Icons and Images

macOS 11 refreshes icon design throughout the system and also introduces multipurpose feature icons that can represent items or functions in sidebars and tables. It also adopts iOS SF Symbols. macOS 11 automatically maps AppKit shared images — such as Action, Unlocked, and Share — to specific symbols. In some cases, a symbol might not have the same size or alignment as the AppKit image it replaces, so check your layout.

SF Symbols.png

Application icons

In macOS 11, application icons combine a rounded-rectangle shape, a front-facing perspective, and a consistent drop shadow.

macOS11 app icons1.png

The new design does not preclude judicious expressiveness. For example, the Preview, Xcode, and TextEdit icons continue to combine depictions of the physical objects that best convey the applicationʼs core purpose, while incorporating the new shape, perspective, and shadow.

macOS11 app icons2.png

Document Icons

To compose a document icon, the system combines your application icon with the familiar folded-corner icon shape. If your application opens or creates a large number of document types, you can also supply a custom centre image or background appearance to help people distinguish them.

macOS11 doc icons.png

Feature Icons

A feature icon can represent an item (or category of items), a technology, or a type of information in a table view or in the content sidebar of a preferences window. A feature icon typically uses the macOS 11 rounded rectangle shape to contain a simple, unambiguous glyph, but it can also use custom shapes and colors. For help designing a feature icon, download the production template included in the Apple Design Resources for macOS.

macOS 11 macOS 10.15
macOS11 feature icon.png macOS10 feature icon.png

Application Accent Colours

In macOS 11, you can specify an accent colour to customize the appearance of your applicationʼs buttons, selection highlighting, and sidebar glyphs. The system applies your accent colour when the current value in the user's General > Accent colour preferences is multicolour.

If users set the Accent colour preferences to a value other than multicolour, the system applies their chosen colour to the relevant items throughout your application, replacing your accent colour. The exception is a sidebar glyph that uses a fixed colour you specify. Because a fixed-colour sidebar glyph uses a specific colour to provide meaning, the system does not override its colour when users change the value of Accent colour preferences. To learn more, see Sidebars.

The iCloud glyph remains teal, even when the other glyphs use orange.

iClould glyph.png

Windows and Views

Throughout macOS 11, windows adopt visual cues from iOS interfaces. For example, windows integrate the sidebar, toolbar, and content areas, use an increased corner radius, and display lightweight controls.

macos11 window view.png

Toolbars and Title Bars

By default, toolbars are taller, window titles can display inline with controls, and toolbar items no longer include a bezel.

macOS 11 macOS 10.15
macOS11 tool-title bar.png macOS10 tool-title bar.png

To match the default toolbar’s increased height, toolbar items automatically use the large control size. The exception is an integrated toolbar-title bar area — such as the one in a Safari window — which continues to use the regular control size. To accommodate the new default size, you’ll probably need to adjust the layout of your toolbar.

macOS 11 macOS 10.15
macOS11 tool bar.png macOS10 tool bar.png

Continuing to use the minSize and maxSize APIs to set the size of a toolbar item can clip the control, because the current values don’t account for the larger default size. Use constraints if you need to specify minimum or maximum sizes for a toolbar control.

When horizontal space is limited, the toolbar can display the Search button in place of the search bar. When users click the Search button, the bar expands; when they click elsewhere in the window, the search bar collapses and the toolbar displays the button again.

macOS11 toolbar search.png

In a preferences window, the toolbar can use SF Symbols, but the title position remains above the toolbar buttons. When needed for clarity, individual toolbar buttons can include colour. To indicate the active preference pane, the window applies a system-provided selection appearance to the selected toolbar button.

macOS 11 macOS 10.15
macOS11 prefs toolbar.png macOS10 prefs toolbar.png

If your window includes multiple panes, you can align different subsets of toolbar items with each pane, so that as people resize the window, each set of items remains above its associated view.


In macOS 11, a sidebar extends to the full height of the window. Within the sidebar, default item spacing, row height, and glyph size all increase, and the selected-item highlight uses a rounded-corner appearance.

macOS 11 macOS 10.15
macOS11 sidebar.png macOS10 sidebar.png

A sidebar’s row height, text, and glyph size depend on its overall size, which can be small, medium, or large. You can set the size programmatically, but users can also change it by selecting a different sidebar icon size in General preferences. The table below shows the differences in default sidebar metrics between macOS 11 and previous versions of macOS.

Sidebar size Sidebar component macOS 11 (default) macOS 10.15 and earlier (default)
Small Row height 24pt 22pt
SF symbol scale Medium †
Glyph size 16pt × 16pt
Text size (style) 11pt (Subhead) 11pt
Medium Row height 28pt 24pt
SF symbol scale Medium
Glyph size 20pt × 20pt 18pt × 18pt
Text size (style) 13pt (Body) 13pt
Large Row height 32pt 32pt
SF symbol scale Medium
Glyph size 24pt × 24pt 24pt × 24pt
Text size (style) 15pt (Title 3) 13pt
All Horizontal spacing between cells 17pt 3pt
Vertical spacing between cells 0pt 2pt
† In some cases, a small sidebar may use small-scale SF Symbols by default.

Using SF Symbols is the easiest way to create sidebar glyphs that use the new metrics. Alternatively, you can use PDF template images to create sidebar glyphs; if you must use bitmap images, be sure to create them in small, medium, and large sizes, at both @1x and @2x resolutions.

By default, sidebar glyphs use the current accent colour (to learn more, see Application Accent Colours). If you need to clarify the meaning of an individual sidebar glyph, you can give it a fixed color that persists regardless of the user’s Accent colour preferences. Don’t use the ability to specify a fixed colour to stylize your application as a whole. In macOS, people expect to see their chosen accent colour throughout all the applications they use.

Table Views

In macOS 11, table views are larger overall, using taller rows, a larger font size, and more space between items to increase visual separation within and around table content. macOS 11 introduces three table-view styles to define different appearances that work well in specific window areas: inset, full-width, and automatic. For developer guidance, see

The inset style adds insets to the expanded spaciousness of macOS 11 tables. Because the inset style increases the visual space around the content, it works well in tables that fill the area between other views — such as sidebars and toolbars — and echoes the changes in sidebar appearance.

macOS11 tableview inset.png

The classic, full-width table style remains available, but automatically includes the required content padding at the beginning and end of each row. The full-width style works best for tables that already have a visual margin around them, such as a table embedded in a preferences pane.

macOS11 tableview classic.png

The automatic style means the system uses the table view’s position in the view hierarchy to help determine its appearance.

To create more spacious tables, macOS 11 uses several new table-view metrics. In the diagrams that follow, you can see how the layout of a table row differs between macOS 11 and macOS 10.15 and earlier.

macOS 11 macOS 10.15
macOS11 tableview layout.png macOS10 tableview layout.png

The following table lists the values for the table-row layout areas shown above.

Table-view metric macOS 11 macOS 10.15 and earlier
Recommended row height 24pt 17pt
Minimum row height for text-only rows 18pt 17pt
Inset at leading and trailing row edges 10pt (inset style); 0pt (other styles)
Padding at leading and trailing row edges 6pt
Intercell spacing (17,0) (3,2)
Text size (style) 13pt (Body) 11pt

In addition to the values listed in the table above, inset-style tables in macOS 11 also include a 10pt vertical inset before the first row and after the last row.

As you adjust the layout of your table content to follow the new metrics:

  • Make sure your icons or glyphs can fit into a 16pt × 16pt area when you use the recommended 24pt row height
  • Consider adding 6 points of space between items within a row to ensure a spacious table appearance
  • If you don’t update your application, the appearance of your tables doesn’t change when your application runs in macOS 11. The exception is a table that implements a sidebar. If you identify the table style as a source list, the system automatically applies the new sidebar appearance. For guidance, see Sidebars; for developer guidance, see

Tip: TIP In macOS 11, a table's width continues to equal the width of its rows, but the new padding and insets prevent columns and cells from covering the entire row. The system also uses the specified style to determine the space to add to row background features, like selection appearance or alternating row colors. If you need to provide content that completely covers a row — such as a custom background appearance — add it to the row instead of the cells.


Sheets no longer unfurl from the bottom edge of the parent window’s toolbar. In macOS 11, a sheet is a rounded rectangle view that floats on top of the dimmed parent window.

macOS 11 macOS 10.15
macOS11 sheet.png macOS10 sheet.png


Alerts are cardlike rectangles that use the same corner radius as all windows in macOS 11. Within an alert, most content is center aligned.

macOS11 alert.png

You can also use red text to emphasize a destructive action in an alert.

macOS11 alert red.png


macOS 11 introduces visual changes to menus and menu content. If you use standard menus and menu items, you get the following default appearances automatically:

  • Menu item titles use the same 13-point font size as sidebars and window content areas.
  • Menu separator lines are 1 point thick and inset from the sides.
  • The selection highlight for a menu item is a rounded rectangle that’s inset from the edges of the menu.
macOS 11 macOS 10.15
macOS11 menu.png macOS10 menu.png


Refreshed AppKit controls — such as checkboxes, pop-up buttons, push buttons, and segmented controls — emphasize simplicity and boldness, similar to iOS controls while maintaining familiar appearances. When you use standard AppKit controls in your application, you shouldn’t have to adjust your interface to adopt the new appearances. The exception is the slider, which is taller.

Slider Size macOS 11 (default) macOS 10.15 and earlier (default)
Without tick marks Regular 28pt 19pt
Small 20pt 15pt
Mini 17pt 13pt
With tick marks Regular 28pt 24pt
Small 20pt 18pt
Mini 17pt 15pt
Slider without tick marks
macOS 11 macOS 10.15
macOS10 slider notick.png macOS11 slider notick.png
Slider with tick marks
macOS 11 macOS 10.15
macOS11 slider ticks.png macOS10 slider ticks.png

Beginning in macOS 11, the track of a slider with tick marks aligns with the center of the thumb.


Beginning in macOS 11, SF Pro is available as a variable font. The variable font format delivers a single package that includes the glyphs for all supported weights — such as regular, bold, and ultralight — in both uprights and italics. The variable format also supports optical sizing, which is a way to interpolate between glyphs to create size-specific versions of SF Pro to fit every design. Optical sizing replaces the need for the fixed-range Text and Display variants of SF Pro.

macOS 11 also introduces support for the full range of text styles, such as body, headline, and callout. Dynamic Type is not available in macOS 11. For guidance, see Typography.


A widget elevates a small amount of useful content from your application. In macOS 11, you can create widgets in small, medium, and large sizes; people choose the size they want when they add your widget to Notification Center.

You can also create widgets for iOS and iPadOS. For guidance, see Widgets; for developer guidance, see WidgetKit.

Removed features

  • Kernel extensions using certain KPIs deprecated in macOS 10.15 Catalina no longer load. Refer to the support page.

New features


macOS Big Sur 11 improves system security by requiring an administrator password when a certificate trust settings change is made in the admin trust domain. Running as the root user alone is no longer sufficient to modify certificate trust. User trust domain settings continue to require confirmation by entering the password for the user’s account. This change may affect you if one of the following is true:

  • You have written scripts which call /usr/bin/security add-trusted-cert -d ... as root.
  • Your process runs as root and calls the SecTrustSettingsSetTrustSettings function to trust a certificate.
  • Workflows that add trust settings in the admin trust domain, such as for an enterprise root certificate, may require modification if the user can’t authenticate as an administrator at the time settings are changed.
    • Workaround: Use Apple Configurator 2 to create and install a configuration profile containing your root certificate.


  • The kern.argmax limit has been increased, allowing programs to receive longer argument lists.
  • Darwin kevent now allows non-parent processes to register for NOTE_EXITSTATUS, which delivers the same values as the wait() family of functions in the event data. Refer to the wait4() man page for more information. This event is subject to the following security checks:
    • The requesting process is allowed to send signals by sandbox restrictions.
    • The requesting process and the target process are running as the same user or the requesting process has root privileges.


  • Support for Web Extensions is now available. Existing Chrome and Firefox extensions can be converted for Safari using xcrun safari-web-extension-converter and distributed through the App Store for use in Safari 14.

Time Machine

  • APFS-formatted backup volumes are now supported for faster, more compact, and more reliable backups. New local and network Time Machine backup destinations are formatted as APFS by default. Time Machine will continue backing up to existing HFS backup volumes.


  • The Hypervisor framework now requires the entitlement.
  • A new Virtualization framework provides high-level APIs to run Linux in a virtual machine.

Built-in dynamic linker cache

New in macOS Big Sur 11 beta, the system ships with a built-in dynamic linker cache of all system-provided libraries. As part of this change, copies of dynamic libraries are no longer present on the filesystem. Code that attempts to check for dynamic library presence by looking for a file at a path or enumerating a directory will fail. Instead, check for library presence by attempting to dlopen() the path, which will correctly check for the library in the cache.

As the libraries are no longer present on the filesystem, it makes it difficult to disassemble them! Fortunately, there are ways to extract the system libraries from the cache. One way is provided by Apple itself: the dyld_shared_cache_util command-line tool. Unfortunately, this tool does not come installed with macOS Big Sur. However, the tool is open source - see dyld_shared_cache_util.

ARM64/AArch64/AppleSilicon Support

macOS 11 Big Sur is the first macOS version that supports Apple's AArch64 processors on the desktop. FPC trunk supports targeting this platform. During the beta period, you will need the Xcode-beta application that you can download from Apple if you are a registered developer (it may also become available as part of a public beta at a later date). The following instructions assume that you are working on an AArch64 Mac, and that the bundle is located in the /Applications folder. You can place it elsewhere and adjust the paths accordingly so long as there are no spaces in the path. The following instructions also assume you have already installed FPC 3.2.0 for Intel.

  1. Compile a native AArch64 compiler
    make distclean
    make FPC=ppcx64 OPT="-ap -FD/Applications/ -XR/Applications/" CPU_TARGET=aarch64 -j 4 FPMAKEOPT="-T 4" all > build.log
  2. Move the created native compiler to a safe place
    cp compiler/ppca64 .
  3. Build a complete native FPC distribution for Darwin/AArch64
    make distclean
    make FPC=$PWD/ppca64 OPT="-ap -FD/Applications/ -XR/Applications/" -j 4 FPMAKEOPT="-T 4" OVERRIDEVERSIONCHECK=1 all > build.log
  4. Install the built toolchain globally (under /usr/local)
    sudo make FPC=$PWD/ppca64 OPT="-ap -FD/Applications/ -XR/Applications/" install
  5. Enable the fpc binary to find the AArch64 compiler (ppca64). You only need to do this once, even if you build/install newer build later on (unless the version number of trunk would change)
    sudo ln -sf /usr/local/lib/fpc/3.3.1/ppca64 /usr/local/bin
  6. Create a file called ".fpc.cfg" (note the starting ".") in your home directory with the following contents
    #include /etc/fpc.cfg

Now you can use either fpc or ppca64 to compile AArch64 programs.


Warning: When you wish to build a newer version later on, make sure to restart at step 1. As always, compiling the trunk sources is only supported when you start with one of the latest two FPC releases, or with a compiler built from the same trunk sources. Starting with a trunk compiler built using previous trunk sources is not and never will be supported.

Apple Big Sur "New Look" external links

Apple Silicon external links