For Mac users, not much has changed in the system over the past six years. Although central apps such as the system settings and, with macOS Tahoe, the entire appearance have changed, hardly anyone will claim that the functions have significantly increased. Internally, however, macOS grew enormously during these years. Howard Oakley has been observing what is changing behind the scenes for many years. His current evaluation reveals steady, strong growth, which reveals some patterns. For this purpose, Oakley carried out an automated count of all bundles located in the “/System/Library” folder. As a starting point for his comparison, he chose macOS 10.14 (Mojave), which was released in September 2018. The number of bundles in the system library has now doubled – from 4,800 to a good 9,800. The kernel extensions also increased in size: Tahoe includes almost 950; in macOS 10.15 it was 515.
Lots of changes under the hood
Oakley notes that there were many changes during this period: Mojave was the last macOS to run 32-bit apps natively and where user and user data resided on the same volume. Both parts of data are now strictly separated from each other, and macOS starts from a cryptographically secured snapshot. Third-party kernel extensions can only be used by actively disabling System Integrity Protection (SIP). Oakley sees the largest numerical increases in system bundles in the context of the introduction of a new Apple silicon generation. When the M3 was introduced, the number of bundles grew by a full 900 entries; with the M4 there were another 600.
Frameworks increasingly private
The bundles collected in the library folder are mostly frameworks that can be used by several programs. Public frameworks are documented interfaces that are also available to third-party developers. Private frameworks, on the other hand, are reserved for Apple. There is a clear trend here: the proportion of public frameworks has fallen from almost 24 to less than 15 percent since 2019. On top of that, Apple is increasingly using the Dynamic Shared Library (dyld) format. Interested developers can only decipher their contents via reverse engineering.
