Hiding SwiftUI views

There are several ways to hide a SwiftUI view, although they don’t all agree on what it means to hide the view. Do you want it to be invisible, or actually not there? To make it invisible you need only set its opacity to zero or use the hidden modifier. But the view will still… Read more

SwiftUI drag & drop does not support file promises

SwiftUI doesn’t offer anything equivalent to NSFilePromiseProvider, i.e. to write data to the drop destination. You have to ditch SwiftUI and use AppKit’s drag & drop APIs instead. FB13583826. Is that it? I know that’s not a very helpful in some sense, but I wasted days trying to figure out how to implement this very… Read more

NSImage is dangerous

Screenshot of an excerpt from Xcode's debug console showing the output of AddressSanitizer, having detected data race involving NSImage.

NSImage is formally documented as largely not thread-safe: The following classes and functions are generally not thread-safe. In most cases, you can use these classes from any thread as long as you use them from only one thread at a time. Check the class documentation for additional details. Apple’s Threading Programming Guide > Appendix A:… Read more

SwiftUI main thread hang detector

Illustration of the MacOS Spinning Pinwheel of Death cursor

This is just a little snippet that is quite useful for reporting when your GUI thread (the main thread / actor) hangs for a significant amount of time. There are numerous heavier-weight tools for analysing this sort of thing, but I’ve found that this simple monitor does what I need most of the time. You… Read more