itshan

⚠️ Private API Warning ⚠️ Use this at your own risk. Apple reserves the right to block you in App Review if you’ve got the stones to use this, and it could always break in a future API version. But also, has anyone actually ever been dinged for this, specifically, when both ChatGPT, Grok, and Claude are all using it? One for the philosophers. We use ObjC runtime introspection to locate the CAFilter class, find the private variableBlur selector, and apply it as a filter to our UIVisualEffectView’s CALayer.  We do something weird but important in our UIVisualEffectView. Instead of just putting the variableBlur on… the view, we search out a subview via subviews.first: the mysterious and subtle _UIVisualEffectBackdropView. This is a smidgen of UIKit internals that actually does the sampling of pixels under the view and applies the initial effect to it. Anything we directly add to the top-level filter is just applied to the already-modified pixels. Putting our filter on this backdrop view directly applies the effect to the pixels sampled under your view. So this looks a bit dodgy right now, with a virtually imperceptible blurring. If any. Not much to see here. Because I am not doing it right (yet).  We set the inputRadius of our variable blur, but we haven’t actually set a variable component to it. We need to add inputMaskImage. This is a CGImage applied to the filter properties, and we multiply each pixel location by the alpha to determine the blur amount across the bar’s height (you can actually do this across any dimension). High alpha = more blurry; low alpha = less blurry. While we’re at it, it’s as good a time as any to refactor out our UIVisualEffectView into a UIKit subclass.  Refactor out our UIVisualEffectView so we can access layoutSubviews() · View gist It’s actually the best time for this, since we need to access view geometry in layoutSubviews() to size our mask correctly. Now we can set inputMaskImage with a vertical gradient, going from white (alpha = 1) at the top to clear (alpha = 0) at the bottom. We also set inputNormalizeEdges to avoid the effect breaking at the screen edges (try it without).  Woah. We have achieved progressive blur. Graphics work is like asbestos removal; you make one breakthrough only to have a puff of spiky death dust billow out from the panel gaps. But we can vacuum up this hard edge to our header by feathering. This is just another gradient mask, this time added to our layer rather than our filter. This leaves the bottom edge of our UIVisualEffectView fully transparent, ramping up to the opaque blur about halfway up. Now we have a true progressive blur, with our content beneath scrolling up towards the void and dispersing their colours. This second gradient mask naturally throws your blur out of whack, making part of it transparent, so you’ll need to spin your wheels a little mucking around with blur radius and gradient curves until you’re happy. This is what we mean by design polish. Read design kisses here to learn my 3 favourite design flourishes 🎨 blog.jacobstechtavern.com/p/…