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Subdivision shows in RealityComposerPro but not when loaded in Simulator
Hello, I am trying to use the subdivision mesh rendering option. I can see it working in RealityComposerPro: But not when loading asset and displaying in Simulator: Using this code: import SwiftUI import RealityKit import RealityKitContent struct AirspaceView: View { // MARK: - VIEW BODY var body: some View { RealityView { content in if let a = try? await Entity(named: "Models/Test/Test.usdc", in: realityKitContentBundle) { content.add(a) } } } } Any ideas why?
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594
Feb ’25
EntityAction for MaterialBaseTint - incorrect colours
Hello, I'm writing an EntityAction that animates a material base tint between two different colours. However, the colour that is being actually set differs in RGB values from that requested. For example, trying to set an end target of R0.5, G0.5, B0.5, results in a value of R0.735357, G0.735357, B0.735357. I can also see during the animation cycle that intermediate actual tint values are also incorrect, versus those being set. My understanding is the the values of material base colour are passed as a SIMD4. Therefore I have a couple of helper extensions to convert a UIColor into this format and mix between two colours. Note however, I don't think the issue is with this functions - even if their outputs are wrong, the final value of the base tint doesn't match the value being set. I wondered if this was a colour space issue? import simd import RealityKit import UIKit typealias Float4 = SIMD4<Float> extension Float4 { func mixedWith(_ value: Float4, by mix: Float) -> Float4 { Float4( simd_mix(x, value.x, mix), simd_mix(y, value.y, mix), simd_mix(z, value.z, mix), simd_mix(w, value.w, mix) ) } } extension UIColor { var float4: Float4 { var r: CGFloat = 0.0 var g: CGFloat = 0.0 var b: CGFloat = 0.0 var a: CGFloat = 0.0 getRed(&r, green: &g, blue: &b, alpha: &a) return Float4(Float(r), Float(g), Float(b), Float(a)) } } struct ColourAction: EntityAction { let startColour: SIMD4<Float> let targetColour: SIMD4<Float> var animatedValueType: (any AnimatableData.Type)? { SIMD4<Float>.self } init(startColour: UIColor, targetColour: UIColor) { self.startColour = startColour.float4 self.targetColour = targetColour.float4 } static func registerEntityAction() { ColourAction.subscribe(to: .updated) { event in guard let animationState = event.animationState else { return } let interpolatedColour = event.action.startColour.mixedWith(event.action.targetColour, by: Float(animationState.normalizedTime)) animationState.storeAnimatedValue(interpolatedColour) } } } extension Entity { func updateColour(from currentColour: UIColor, to targetColour: UIColor, duration: Double, endAction: @escaping (Entity) -> Void = { _ in }) { let colourAction = ColourAction(startColour: currentColour, targetColour: targetColour, endedAction: endAction) if let colourAnimation = try? AnimationResource.makeActionAnimation(for: colourAction, duration: duration, bindTarget: .material(0).baseColorTint) { playAnimation(colourAnimation) } } } The EntityAction can only be applied to an entity with a ModelComponent (because of the material), so it can be called like so: guard let modelComponent = entity.components[ModelComponent.self], let material = modelComponent.materials.first as? PhysicallyBasedMaterial else { return } let currentColour = material.baseColor.tint let targetColour = UIColor(_colorLiteralRed: 0.5, green: 0.5, blue: 0.5, alpha: 1.0) entity.updateColour(from:currentColour, to: targetColour, duration: 2)
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598
Feb ’25
RealityKit particleEmitter delay starting when toggling isEmitting
I have a scene built up in RealityComposerPro, in which I've added a ParticleEmitter with isEmitting set to False and 'Loop' set to True. In my app, when I toggle isEmitting to True there can be a delay of a few seconds before the ParticleEmitter starts. However, if I programatically add the emitter in code at that point, it starts immediately. To be clear, I'm seeing this on the VisionOS simulator - I don't have access to a device at this time. Am I misunderstanding how to control the ParticleEmitter when I need precise control on when it starts.
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568
Feb ’25
When to use an AnchorEntity or HandTrackingProvider in VisionOS
As I understand it there are two ways I can track a hand, or a joint, in RealityKit: either, create an AnchorEntity, for example AnchorEntity(.hand(.left, location: .palm)) or, set up an ARSession with a HandTrackingProvider ( a lot more code which I haven't repeated here). Assuming this is correct, when would I want to use one over the other?
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Feb ’25
Custom EntityAction - different behaviour VisionOS 2.6 vs 26
I implemented an EntityAction to change the baseColor tint - and had it working on VisionOS 2.x. import RealityKit import UIKit typealias Float4 = SIMD4<Float> extension UIColor { var float4: Float4 { if cgColor.numberOfComponents == 4, let c = cgColor.components { Float4(Float(c[0]), Float(c[1]), Float(c[2]), Float(c[3])) } else { Float4() } } } struct ColourAction: EntityAction { // MARK: - PUBLIC PROPERTIES let startColour: Float4 let targetColour: Float4 // MARK: - PUBLIC COMPUTED PROPERTIES var animatedValueType: (any AnimatableData.Type)? { Float4.self } // MARK: - INITIATION init(startColour: UIColor, targetColour: UIColor) { self.startColour = startColour.float4 self.targetColour = targetColour.float4 } // MARK: - PUBLIC STATIC FUNCTIONS @MainActor static func registerEntityAction() { ColourAction.subscribe(to: .updated) { event in guard let animationState = event.animationState else { return } let interpolatedColour = event.action.startColour.mixedWith(event.action.targetColour, by: Float(animationState.normalizedTime)) animationState.storeAnimatedValue(interpolatedColour) } } } extension Entity { // MARK: - PUBLIC FUNCTIONS func changeColourTo(_ targetColour: UIColor, duration: Double) { guard let modelComponent = components[ModelComponent.self], let material = modelComponent.materials.first as? PhysicallyBasedMaterial else { return } let colourAction = ColourAction(startColour: material.baseColor.tint, targetColour: targetColour) if let colourAnimation = try? AnimationResource.makeActionAnimation(for: colourAction, duration: duration, bindTarget: .material(0).baseColorTint) { playAnimation(colourAnimation) } } } This doesn't work in VisionOS 26. My current fix is to directly set the material base colour - but this feels like the wrong approach: @MainActor static func registerEntityAction() { ColourAction.subscribe(to: .updated) { event in guard let animationState = event.animationState, let entity = event.targetEntity, let modelComponent = entity.components[ModelComponent.self], var material = modelComponent.materials.first as? PhysicallyBasedMaterial else { return } let interpolatedColour = event.action.startColour.mixedWith(event.action.targetColour, by: Float(animationState.normalizedTime)) material.baseColor.tint = UIColor(interpolatedColour) entity.components[ModelComponent.self]?.materials[0] = material animationState.storeAnimatedValue(interpolatedColour) } } So before I raise this as a bug, was I doing anything wrong in the former version and got lucky? Is there a better approach?
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125
Sep ’25
SwiftUI Picker layout under MacOS26
Prior to MacOS 26, Multiple Pickers could be laid out with a uniform width. For example: struct LayoutExample: View { let fruits = ["apple", "banana", "orange", "kiwi"] let veg = ["carrot", "cauliflower", "peas", "Floccinaucinihilipilification Cucurbitaceae"] @State private var selectedFruit: String = "kiwi" @State private var selectedVeg: String = "carrot" var body: some View { VStack(alignment: .leading) { Picker(selection: $selectedFruit) { ForEach(fruits, id: \.self, content: Text.init) } label: { Text("Fruity choice") .frame(width: 150, alignment: .trailing) } .frame(width: 300) Picker(selection: $selectedVeg) { ForEach(veg, id: \.self, content: Text.init) } label: { Text("Veg") .frame(width: 150, alignment: .trailing) } .frame(width: 300) } } } Renders like this, prior to MacOS26: But now looks like this under MacOS 26: Is there anyway to control the size of the picker selection in MacOS 26?
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89
Sep ’25
SwiftUI TextField selection - strange initial values with iOS
When using a TextField with axis to set to .vertical on iOS, it sets a bound selection parameter to an erroneous value. Whilst on MacOS it performs as expected. Take the following code: import SwiftUI @main struct SelectionTestApp: App { var body: some Scene { WindowGroup { ContentView() } } } struct ContentView: View { @FocusState private var isFocused: Bool @State private var text = "" @State private var textSelection: TextSelection? = nil var body: some View { TextField("Label", text: $text, selection: $textSelection, axis: .vertical) .onChange(of: textSelection, initial: true) { if let textSelection { print("textSelection = \(textSelection)") } else { print("textSelection = nil") } } .focused($isFocused) .task { isFocused = true } } } Running this on MacOS target gives the following on the console: textSelection = nil textSelection = TextSelection(indices: SwiftUI.TextSelection.Indices.selection(Range(0[any]..<0[any])), affinity: SwiftUI.TextSelectionAffinity.downstream) Running the code on iOS gives: textSelection = TextSelection(indices: SwiftUI.TextSelection.Indices.selection(Range(1[any]..<1[any])), affinity: SwiftUI.TextSelectionAffinity.upstream) textSelection = TextSelection(indices: SwiftUI.TextSelection.Indices.selection(Range(1[any]..<1[any])), affinity: SwiftUI.TextSelectionAffinity.upstream) Note here the range is 1..<1 - which is incorrect. Also of side interest this behaviour changes if you remove the axis parameter: textSelection = nil Am I missing something, or is this a bug?
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149
Oct ’25
VideoPlayer crashes on Archive build
I have found that following code runs without issue from Xcode, either in Debug or Release mode, yet crashes when running from the binary produced by archiving - i.e. what will be sent to the app store. import SwiftUI import AVKit @main struct tcApp: App { var body: some Scene { WindowGroup { VideoPlayer(player: nil) } } } This is the most stripped down code that shows the issue. One can try and point the VideoPlayer at a file and the same issue will occur. I've attached the crash log: Crash log Please note that this was seen with Xcode 26.2 and MacOS 26.2.
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420
Dec ’25
How to correctly move a TextField selection cursor when inserting UTF16 text
I'm trying to implement a feature whereby a user can tap a button to insert a character at the cursor in a TextField - the cursor then needs to be moved forward to be in front of the insert character. I'm having trouble with characters such as π which are UTF16 encoded. In the following sample app, enter the following sequence: Enter 9 by keyboard tap + Enter 9 by keyboard tap π Enter 9 via keyboard tap + he TextField will show '9+9π+9' (i.e. the final + is inserted before 9 rather than after it. Any insight into what I am doing wrong? import SwiftUI @main struct TextInsertApp: App { var body: some Scene { WindowGroup { ContentView() } } } struct ContentView: View { @State private var text: String = "" @State private var selection: TextSelection? = nil var body: some View { TextField("", text: $text, selection: $selection) .background(.gray.opacity(0.4)) Button("+") { insert("+") } Button("π") { insert("π") } } func insert(_ insertString: String) { if let selection { if case let .selection(range) = selection.indices { if selection.isInsertion { text.insert(contentsOf: insertString, at: range.lowerBound) } else { text.replaceSubrange(range, with: insertString) } let cursor = text.utf16.index(range.upperBound, offsetBy: insertString.count) self.selection = .init(insertionPoint: cursor) } } else { text += insertString selection = .init(range: text.utf16.endIndex..<text.utf16.endIndex) } } }
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