It's not missing. It moved. It's now in the bottom-left corner of the Interface Builder area of the screen. It's just to the left of the filter search bar, just above the "Deactivate Breakpoints" button.

Lots of bugs with UISlider.TrackConfiguration. neutralValue only works if the slider's min value is 0.0 and the max value is 1.0 and the slider's value is between 0 and 1. And of course neutralValue is also in the range 0...1. allowsTickValuesOnly is not honored if ticks are set. Even when set to false it acts as if it is true. enabledRange only respects the upper range, not the lower range. Time to file a bug report. P.S. You can work around the neutralValue issue by converting the slider's value of 0...1 with let desiredValue = slider.value * 20 - 10. That will give you a result in the range -10...10.

UISlider now has a trackConfiguration property of type UISlider.TrackConfiguration which in turn has a neutralValue property. I can't speak to a SwiftUI Slider.

Unfortunately iOS 26 no longer honors any tintColor set at the UIWindow, UINavigationBar, or UIToolbar level for any glass components. So this includes any UIBarButtomItems including standard back bar items. As you've seen, you can only tint individual bar button items. Everyone affected by this should file a bug report using Feedback Assistant so Apple knows that this needs to be fixed.

I forgot to mention that the Feedback Assistant now (as of a day or two ago) has much saner options for versions. Thanks. P.S. I just saw your comment confirming this as well.

If you don't want to backup the simulators, then setup Time Machine to exclude ~/Library/Developer/CoreSimulator If you don't want to backup the derived data used during builds, then exclude ~/Library/Developer/Xcode/DerivedData

The Pop-up button page in the HIG has a link to SwiftUI MenuPickerStyle along with a link to NSPopUpButton for AppKit. I'm actually not familiar with AppKit or SwiftUI (just UIKit) but hopefully that points you in the right direction.

You get the new glass look automatically. Just create normal UIBarButtonItem instances with appropriate images and set them to the view controller's toolbarItems. You automatically get the look in the second picture. You just might need to correctly use fixedSpace or flexibleSpace to get the proper spacing. See Build a UIKit app with the new design. Jump to the "Navigation and toolbars" section. If you still need help, post your relevant code to get better help.

My old app icons and the new glass icon file do not have the same name and I do not get any errors.

Correct

To add the new icon file to your project, go to the Xcode project navigator and right-click on the folder that you want to put the icon file in. It doesn't need to be in any specific folder in your project. Choose "Add Files to "MyProject"... from the context menu. Then select and add the new icon file. Once the icon file is added to your project, see https://developer.apple.com/forums/thread/787576 for a thread on setting up your target to use the new icon. It also explains how use both the new and the old icons (assuming you want to support macOS/iOS 26 as well as prior versions).

I'm running a MacBook Pro with a built in trackpad on macOS 15.5. I just used UTM to create a VM for macOS 26. Initially the Settings app in the macOS 26 VM did not show either a mouse or trackpad. I shutdown the VM. Then in UTM I highlighted the macOS 26 VM on the left and then clicked the settings icon (three little sliders icon) in the top-right corner of UTM. Then select Virtualization. The Pointer setting was set to Mac Trackpad. I changed it to Generic Mouse. Then I saved the change and launched the VM. I brought up the Settings app in the running macOS 26 VM and I then I saw Mouse between Keyboard and Printers & Scanners. I selected Mouse to bring up the mouse settings which includes the Natural Scrolling toggle. I turned it off and life was good again. I don't know if the above will work with your Mac and mouse but it worked with my Mac and trackpad. To me there is nothing "natural" about "Natural Scrolling". Too many decades of muscle memory of proper scrolling. :)

In my existing app, after opening the project in Xcode 26 and adding the new glass icon file (AppIconGlass.icon in my case) to the project, I needed to do the following: Select your target Select the General tab Scroll down to the "App Icons and Launch Screen" section. In the "App Icon" field, enter the name of the new glass icon, minus the extension (AppIconGlass in my case). Enable the "App Icons Source - Include all app icon assets" option. That's it. Just make sure you do not have any manual entries in your Info.plist related to the app icons. Xcode will add them automatically as part of the build. And it will do so in a way that shows the new glass icon for iOS 26 and the previous app icons for iOS 18 and earlier.

Start with the UIKit documentation. There you will find a link for App and Environment. That in turn has a link for Managing your app’s life cycle and Scenes.

Run Xcode 26 under macOS 26. It's the OS, not the app that provides the new glassy look.