{"id":48784,"date":"2025-08-05T14:29:57","date_gmt":"2025-08-05T18:29:57","guid":{"rendered":"https:\/\/mjtsai.com\/blog\/?p=48784"},"modified":"2026-03-06T09:06:18","modified_gmt":"2026-03-06T14:06:18","slug":"macos-tahoe-26-developer-beta-5","status":"publish","type":"post","link":"https:\/\/mjtsai.com\/blog\/2025\/08\/05\/macos-tahoe-26-developer-beta-5\/","title":{"rendered":"macOS Tahoe 26 Developer Beta 5"},"content":{"rendered":"<p><a href=\"https:\/\/www.macrumors.com\/2025\/08\/05\/apple-seeds-macos-tahoe-beta-5-to-developers\/\">Juli Clover<\/a> (<a href=\"https:\/\/mrmacintosh.com\/macos-tahoe-beta-5-everything-you-need-to-know\/\">Mr. Macintosh<\/a>):<\/p>\n<blockquote cite=\"https:\/\/www.macrumors.com\/2025\/08\/05\/apple-seeds-macos-tahoe-beta-5-to-developers\/\">\n<p>Apple today provided developers with the fifth beta of macOS Tahoe 26 for testing purposes, with the update coming two weeks after the fourth beta.<\/p>\n<\/blockquote>\n\n<p>There are <a href=\"https:\/\/x.com\/mjtsai\/status\/1951059190216270054\">no updates<\/a> to the <a href=\"https:\/\/developer.apple.com\/documentation\/macos-release-notes\/macos-26-release-notes\">release notes<\/a>, which still say Beta 4.<\/p>\n\n<p><a href=\"https:\/\/mastodon.social\/@marioguzman\/114977561003194566\">Mario Guzm&aacute;n<\/a>:<\/p>\n<blockquote cite=\"https:\/\/mastodon.social\/@marioguzman\/114977561003194566\">\n<p>THIS IS THE NEW MACINTOSH HD ICON?! WTF<\/p>\n<\/blockquote>\n\n<p>Previously:<\/p>\n<ul>\n<li><a href=\"https:\/\/mjtsai.com\/blog\/2025\/07\/22\/macos-tahoe-26-developer-beta-4\/\">macOS Tahoe 26 Developer Beta 4<\/a><\/li>\n<li><a href=\"https:\/\/mjtsai.com\/blog\/2025\/06\/30\/assorted-notes-on-liquid-glass\/\">Assorted Notes on Liquid Glass<\/a><\/li>\n<\/ul>\n\n<p id=\"macos-tahoe-26-developer-beta-5-update-2025-08-06\">Update (<a href=\"#macos-tahoe-26-developer-beta-5-update-2025-08-06\">2025-08-06<\/a>): The <a href=\"https:\/\/developer.apple.com\/documentation\/macos-release-notes\/macos-26-release-notes\">release notes<\/a> now say &ldquo;beta 5&rdquo; and call out a few changes (integrated into the list, so you have to search for them):<\/p>\n<blockquote cite=\"https:\/\/developer.apple.com\/documentation\/macos-release-notes\/macos-26-release-notes\"><p>In beta 5 SDK, CoreData changed several <code>Sendable<\/code> annotations to resolve compatibility issues with Swift 6&rsquo;s new <code>MainActor<\/code> default isolation feature. These changes include marking <code>NSManagedObject<\/code> as <code>NS_SWIFT_NONISOLATED NS_SWIFT_NONSENDABLE<\/code>, marking <code>NSManagedObjectContext<\/code> as <code>NS_SWIFT_NONISOLATED NS_SWIFT_SENDABLE<\/code>, and requiring <code>NS_SWIFT_SENDABLE<\/code> closures for the family of <code>perform<\/code>, <code>performBlock<\/code>, <code>performBlockAndWait<\/code> and similar methods. These changes are ABI compatible with past releases but might introduce new warnings while building source code that violates the longstanding CoreData concurrency guidelines.<\/p><p><code>NSManagedObject<\/code> are mutable reference types inextricably related to others in a graph and cannot be made <code>Sendable<\/code>. They are expected to be isolated to the scope of the <code>NSManagedObjectContext<\/code> that creates or fetches them. <code>NSManagedObjectContext<\/code> is a style of actor which encapsulates its own dispatch queue. While it&rsquo;s impermissible to use many methods on <code>NSManagedObjectContext<\/code> from other threads, it is permissible to pass references around to invoke the <code>performBlock<\/code> family of methods, for the purpose of routing a <code>Sendable<\/code> closure to its managed dispatch queue. CoreData supports a user default <code>-com.apple.CoreData.ConcurrencyDebug 1<\/code> which can be used to enable additional assertions.<\/p><\/blockquote>\n\n<p>I assume this <a href=\"https:\/\/www.donnywals.com\/using-launch-arguments-for-easier-core-data-debugging\/\">debugging default<\/a> still breaks <code>NSAsynchronousFetchRequest<\/code> (FB8438285).<\/p>\n\n<p><a href=\"https:\/\/www.macrumors.com\/2025\/08\/05\/macintosh-hd-macos-tahoe\/\">Juli Clover<\/a> (<a href=\"https:\/\/hardware.slashdot.org\/story\/25\/08\/05\/2221223\/rip-to-the-macintosh-hd-hard-drive-icon-2000-2025\">Slashdot<\/a>):<\/p>\n<blockquote cite=\"https:\/\/www.macrumors.com\/2025\/08\/05\/macintosh-hd-macos-tahoe\/\">\n<p>Apple has been updating some classic Mac icons during the macOS Tahoe beta, upsetting some longtime Mac users who prefer the original look.<\/p>\n<\/blockquote>\n\n<p><a href=\"https:\/\/x.com\/ClassicII_MrMac\/status\/1952805847576527226\">Mr. Macintosh<\/a>:<\/p>\n<blockquote cite=\"https:\/\/x.com\/ClassicII_MrMac\/status\/1952805847576527226\">\n<p>RIP Macintosh HD icon (2001-2025) &#x1FAA6;&#x1F490;<\/p>\n<\/blockquote>\n\n<p><a href=\"https:\/\/duck.haus\/@joesteel\/114978125935825343\">Joe Rosensteel<\/a>:<\/p>\n<blockquote cite=\"https:\/\/duck.haus\/@joesteel\/114978125935825343\">\n<p>An external SSD enclosure that resembles a Samsung T7 but with offset port and vent holes like a Mophie power bank. It makes more sense than a naked hard drive because people always need external storage for their Macs that ship with almost none and can&rsquo;t house any internal drives anyway. Bold move to put the Apple logo on it though.<\/p>\n<\/blockquote>\n\n<p>Making it look like an SSD is fine, but why make it look like an <em>external<\/em> SSD? Anyway, the main problem is that <a href=\"https:\/\/mastodon.online\/@octothorpe\/114978554729765083\">it<\/a> <a href=\"https:\/\/mastodon.social\/@leebennett\/114979038672609574\">isn&rsquo;t<\/a> <a href=\"https:\/\/x.com\/flarup\/status\/1952871915112284673\">drawn<\/a> <a href=\"https:\/\/x.com\/DamienPetrilli\/status\/1953122990519906656\">well<\/a>. The <a href=\"https:\/\/mastodon.social\/@nicklockwood\/114981015250406041\">perspective<\/a> looks wrong and is very off-putting. They did the same thing with the new icon for mounted disk images.<\/p>\n\n<p><a href=\"https:\/\/pxlnv.com\/linklog\/tahoe-macintosh-hd-icon\/\">Nick Heer<\/a>:<\/p>\n<blockquote cite=\"https:\/\/pxlnv.com\/linklog\/tahoe-macintosh-hd-icon\/\">\n<p>I want to put a finer point on the problem with this icon: it is not a mere aesthetic preference or a reaction to change, but a simple acknowledgement that this icon is not good. It has a generic quality, a lack of personality. The perspective does not make sense, either. It is just a sad grey box without any connection to literal data storage on a modern Mac, the &ldquo;Macintosh HD&rdquo; label beside it on the Desktop, or any object in the real world.<\/p>\n<\/blockquote>\n\n<p><a href=\"https:\/\/mastodon.social\/@BasicAppleGuy\/114982213630020070\">BasicAppleGuy<\/a>:<\/p>\n<blockquote cite=\"https:\/\/mastodon.social\/@BasicAppleGuy\/114982213630020070\">\n<p>macOS Icon History<br \/>\nPreview<\/p>\n<\/blockquote>\n\n<p><a href=\"https:\/\/x.com\/krzyzanowskim\/status\/1952891526734069785\">Marcin Krzyzanowski<\/a>:<\/p>\n<blockquote cite=\"https:\/\/x.com\/krzyzanowskim\/status\/1952891526734069785\"><p>these small things that makes the beta 5 (already) feels half baked. the basic controls have broken layout.<\/p><\/blockquote>\n\n<p><a href=\"https:\/\/mastodon.social\/@lapcatsoftware\/114977408929624587\">Jeff Johnson<\/a>:<\/p>\n<blockquote cite=\"https:\/\/mastodon.social\/@lapcatsoftware\/114977408929624587\">\n<p>They&rsquo;ve glassed up the video play button in Safari.<\/p>\n<\/blockquote>\n\n<p><a href=\"https:\/\/mastodon.social\/@colincornaby\/114978908010608132\">Colin Cornaby<\/a>:<\/p>\n<blockquote cite=\"https:\/\/mastodon.social\/@colincornaby\/114978908010608132\">\n<p>I real curious to see what Apple pro apps like Logic and Final Cut do with Liquid Glass.<\/p>\n<\/blockquote>\n\n<p><a href=\"https:\/\/mastodon.social\/@isaiah\/114980735000908516\">Isaiah Carew<\/a>:<\/p>\n<blockquote cite=\"https:\/\/mastodon.social\/@isaiah\/114980735000908516\">\n<p>i continue to believe that OS 26 is being designed by people that hate computers and don&rsquo;t understand the people use them.<\/p>\n<\/blockquote>\n\n<p>Previously:<\/p>\n<ul>\n<li><a href=\"https:\/\/mjtsai.com\/blog\/2024\/11\/25\/swift-vision-improving-the-approachability-of-data-race-safety\/\">Swift Vision: Improving the Approachability of Data-Race Safety<\/a><\/li>\n<\/ul>\n\n<p id=\"macos-tahoe-26-developer-beta-5-update-2025-08-08\">Update (<a href=\"#macos-tahoe-26-developer-beta-5-update-2025-08-08\">2025-08-08<\/a>): <a href=\"https:\/\/mastodon.social\/@stroughtonsmith\/114987419416210088\">Steve Troughton-Smith<\/a>:<\/p>\n<blockquote cite=\"https:\/\/mastodon.social\/@stroughtonsmith\/114987419416210088\"><p>I guess it shouldn&rsquo;t be surprising, but with macOS 26 we have finally squandered the last of the &lsquo;free&rsquo; graphics performance uplift offered by the M1 chip. Window server has a hard time maintaining 60fps at 4K for moving a single Finder window around. Let&rsquo;s hope some of that improves in future betas, but I&rsquo;m not holding my breath<\/p><\/blockquote>\n\n<p><a href=\"https:\/\/mastodon.social\/@agiletortoise\/114984386872032223\">Greg Pierce<\/a>:<\/p>\n<blockquote cite=\"https:\/\/mastodon.social\/@agiletortoise\/114984386872032223\">\n<p>There are some weird and worrisome problems with beta 5, at least on Mac.<\/p>\n<p>The App Store version of Drafts crashes on launch on macOS 26b5, getting stuck in recursive layout loop.<\/p>\n<p>I worked around that crash, and can build-and-run on 26b5 and 15.5, no problem &#x2013; but if I upload that build to TestFlight, it works fine on 26b5, but crashes on launch with a different runtime issue on 15.5.<\/p>\n<\/blockquote>\n\n<p><a href=\"https:\/\/pdx.social\/@louie\/114989689416984046\">Louis Mantia<\/a>:<\/p>\n<blockquote cite=\"https:\/\/pdx.social\/@louie\/114989689416984046\">\n<p>One good feature in macOS 26 is the ability to change color for all folders on your computer. I&rsquo;m rocking that Classic Mac light indigo color right now. &#x263A;&#xFE0F;<\/p>\n<\/blockquote>\n\n<p><a href=\"https:\/\/pdx.social\/@siracusa@mastodon.social\/114990556198264532\">John Siracusa<\/a>:<\/p>\n<blockquote cite=\"https:\/\/pdx.social\/@siracusa@mastodon.social\/114990556198264532\">\n<p>I like that Labels in the Finder now change the color of the whole folder (like they used to in classic Mac OS)&#8230;except in the Dock, where all folders are always the same color. (FB18696288)<\/p>\n<\/blockquote>\n\n<p><a href=\"https:\/\/mastodon.social\/@BasicAppleGuy\/114993532340469737\">BasicAppleGuy<\/a>:<\/p>\n<blockquote cite=\"https:\/\/mastodon.social\/@BasicAppleGuy\/114993532340469737\">\n<p>macOS Icon History<br \/>\nMission Control<\/p>\n<\/blockquote>\n\n<p><a href=\"https:\/\/x.com\/flarup\/status\/1953186365367017822\">Michael Flarup<\/a> has a comparison of the old and new drive icons.<\/p>\n\n<p><a href=\"https:\/\/pdx.social\/@louie\/114990123597994835\">Louis Mantia<\/a>:<\/p>\n<blockquote cite=\"https:\/\/pdx.social\/@louie\/114990123597994835\">\n<p>The [window corner] mess Apple created cannot be overstated. Truly.<\/p>\n<\/blockquote>\n\n<p id=\"macos-tahoe-26-developer-beta-5-update-2026-03-06\">Update (<a href=\"#macos-tahoe-26-developer-beta-5-update-2026-03-06\">2026-03-06<\/a>): <a href=\"https:\/\/fatbobman.com\/en\/posts\/sendable-nsmanagedobjectcontext\/\">Fatbobman<\/a> (<a href=\"https:\/\/mastodon.social\/@fatbobman\/116170881926560668\">Mastodon<\/a>):<\/p>\n<blockquote cite=\"https:\/\/fatbobman.com\/en\/posts\/sendable-nsmanagedobjectcontext\/\">\n<p>When the same concurrency-related code fails to compile in Xcode 16 but builds cleanly in Xcode 26, what&rsquo;s your first instinct? Mine was that the compiler had gotten smarter &mdash; but reality turned out to be more nuanced. This post documents a recent debugging journey: starting from a test failure, tracing all the way down to the Core Data SDK interface, and ultimately discovering that the key change had nothing to do with the Swift compiler itself &mdash; it was how <code>NSManagedObjectContext<\/code> is imported into Swift that had changed.<\/p>\n<p>[&#8230;]<\/p>\n<p>Although <code>NSManagedObjectContext<\/code> can now be passed across isolation domains, that doesn&rsquo;t mean you should do so in production. Looking at SwiftData&rsquo;s interface, <code>ModelContext<\/code> does have an <code>@unchecked Sendable<\/code> extension &mdash; but it&rsquo;s marked <code>unavailable<\/code>, with an explicit note that <code>contexts cannot be shared across concurrency contexts<\/code>. Unless you have a genuine need to share context across isolation boundaries, the right approach is still to follow Core Data&rsquo;s established concurrency guidelines.<\/p>\n<\/blockquote>","protected":false},"excerpt":{"rendered":"<p>Juli Clover (Mr. Macintosh): Apple today provided developers with the fifth beta of macOS Tahoe 26 for testing purposes, with the update coming two weeks after the fourth beta. There are no updates to the release notes, which still say Beta 4. Mario Guzm&aacute;n: THIS IS THE NEW MACINTOSH HD ICON?! WTF Previously: macOS Tahoe [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"apple_news_api_created_at":"2025-08-05T18:29:59Z","apple_news_api_id":"efc8431d-c922-4b6c-a5bb-f851c4aa50a7","apple_news_api_modified_at":"2026-03-06T14:06:35Z","apple_news_api_revision":"AAAAAAAAAAAAAAAAAAAACQ==","apple_news_api_share_url":"https:\/\/apple.news\/A78hDHckiS2ylu_hRxKpQpw","apple_news_coverimage":0,"apple_news_coverimage_caption":"","apple_news_is_hidden":false,"apple_news_is_paid":false,"apple_news_is_preview":false,"apple_news_is_sponsored":false,"apple_news_maturity_rating":"","apple_news_metadata":"\"\"","apple_news_pullquote":"","apple_news_pullquote_position":"","apple_news_slug":"","apple_news_sections":"\"\"","apple_news_suppress_video_url":false,"apple_news_use_image_component":false,"footnotes":""},"categories":[2],"tags":[109,77,545,2785,30,2308,2742,71,2200],"class_list":["post-48784","post","type-post","status-publish","format-standard","hentry","category-technology","tag-coredata","tag-design","tag-icons","tag-liquid-glass","tag-mac","tag-macos-beta","tag-macos-tahoe-26","tag-programming","tag-swift-concurrency"],"apple_news_notices":[],"_links":{"self":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/48784","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/comments?post=48784"}],"version-history":[{"count":11,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/48784\/revisions"}],"predecessor-version":[{"id":51181,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/48784\/revisions\/51181"}],"wp:attachment":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/media?parent=48784"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/categories?post=48784"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/tags?post=48784"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}