I've got a full-screen animation of a bunch of circles filled with gradients, with plenty of (careless) overdraw, plus real-time audio processing driving the animation, plus the overhead of SwiftUI's dependency analysis, and that app uses less energy (on iPhone 13) than the Xcode "Metal Game" template which is a rotating textured cube (a trivial GPU workload). Why is that? How can I investigate further? Does CoreAnimation have access to a compositor fast-path that a Metal app cannot access? Maybe another data point: when I do the same circles animation using SwiftUI's Canvas, the energy use is "Very High" and GPU utilization is also quite high. Eventually the phone's thermal state goes "Serious" and I get a message on the device that "Charging will resume when iPhone returns to normal temperature".

I'm trying to create a MTLFXTemporalScaler as follows (this is adapted from the sample code): func updateTemporalScaler() { let desc = MTLFXTemporalScalerDescriptor() desc.inputWidth = renderTarget.renderSize.width desc.inputHeight = renderTarget.renderSize.height desc.outputWidth = renderTarget.windowSize.width desc.outputHeight = renderTarget.windowSize.height desc.colorTextureFormat = .bgra8Unorm desc.depthTextureFormat = .depth32Float desc.motionTextureFormat = .rg16Float desc.outputTextureFormat = .bgra8Unorm guard let temporalScaler = desc.makeTemporalScaler(device: device) else { fatalError("The temporal scaler effect is not usable!") } temporalScaler.motionVectorScaleX = Float(renderTarget.renderSize.width) temporalScaler.motionVectorScaleY = Float(renderTarget.renderSize.height) mfxTemporalScaler = temporalScaler } I'm getting the following error the 3rd time the code is called: /AppleInternal/Library/BuildRoots/91a344b1-f985-11ee-b563-fe8bc7981bff/Library/Caches/com.apple.xbs/Sources/MetalPerformanceShadersGraph/mpsgraph/MetalPerformanceShadersGraph/Runtimes/MPSRuntime/Operations/RegionOps/ANRegion.mm:855: failed assertion `ANE intermediate buffer handle not same!' When I copy the code out to a playground, it succeeds when called with the same sequence of descriptors. Does this seem like a bug with MTLFXTemporalScaler?

I've been using an XCFramework of LuaJIT for years now in my app. After upgrading to Xcode 16, calls to the LuaJIT interpreter started segfaulting on macOS in release mode only. Works on iOS (both debug/release). Works fine with Xcode 15.4 (both debug/release). I have a very simple repro. Wondering what could actually cause that sort of thing, given it's the same XCFramework (i.e. precompiled with optimization on). Guessing this is something having to do with the way LuaJIT is called, or the environment in which it runs, when the optimizer is turned on. https://github.com/LuaJIT/LuaJIT/issues/1290 (FB15512926)

In my Swift app, Xcode has decided to put various important settings like, SWIFT_VERSION under "User Defined." Does anyone know why?

I'm trying to switch to UIKit's document lifecycle due to serious bugs with SwiftUI's version. However I'm noticing the template project from Xcode isn't compatible with Swift 6 (I already migrated my app to Swift 6.). To reproduce: File -> New -> Project Select "Document App" under iOS Set "Interface: UIKit" In Build Settings, change Swift Language Version to Swift 6 Run app Tap "Create Document" Observe: crash in _dispatch_assert_queue_fail Does anyone know of a work around other than downgrading to Swift 5?

I'm streaming mp3 audio data using URLSession/AudioFileStream/AVAudioConverter and getting occasional silent buffers and glitches (little bleeps and whoops as opposed to clicks). The issues are present in an offline test, so this isn't an issue of underruns. Doing some buffering on the input coming from the URLSession (URLSessionDataTask) reduces the glitches/silent buffers to rather infrequent, but they do still happen occasionally. var bufferedData = Data() func parseBytes(data: Data) { bufferedData.append(data) // XXX: this buffering reduces glitching // to rather infrequent. But why? if bufferedData.count > 32768 { bufferedData.withUnsafeBytes { (bytes: UnsafeRawBufferPointer) in guard let baseAddress = bytes.baseAddress else { return } let result = AudioFileStreamParseBytes(audioStream!, UInt32(bufferedData.count), baseAddress, []) if result != noErr { print("❌ error parsing stream: \(result)") } } bufferedData = Data() } } No errors are returned by AudioFileStream or AVAudioConverter. func handlePackets(data: Data, packetDescriptions: [AudioStreamPacketDescription]) { guard let audioConverter else { return } var maxPacketSize: UInt32 = 0 for packetDescription in packetDescriptions { maxPacketSize = max(maxPacketSize, packetDescription.mDataByteSize) if packetDescription.mDataByteSize == 0 { print("EMPTY PACKET") } if Int(packetDescription.mStartOffset) + Int(packetDescription.mDataByteSize) > data.count { print("❌ Invalid packet: offset \(packetDescription.mStartOffset) + size \(packetDescription.mDataByteSize) > data.count \(data.count)") } } let bufferIn = AVAudioCompressedBuffer(format: inFormat!, packetCapacity: AVAudioPacketCount(packetDescriptions.count), maximumPacketSize: Int(maxPacketSize)) bufferIn.byteLength = UInt32(data.count) for i in 0 ..< Int(packetDescriptions.count) { bufferIn.packetDescriptions![i] = packetDescriptions[i] } bufferIn.packetCount = AVAudioPacketCount(packetDescriptions.count) _ = data.withUnsafeBytes { ptr in memcpy(bufferIn.data, ptr.baseAddress, data.count) } if verbose { print("handlePackets: \(data.count) bytes") } // Setup input provider closure var inputProvided = false let inputBlock: AVAudioConverterInputBlock = { packetCount, statusPtr in if !inputProvided { inputProvided = true statusPtr.pointee = .haveData return bufferIn } else { statusPtr.pointee = .noDataNow return nil } } // Loop until converter runs dry or is done while true { let bufferOut = AVAudioPCMBuffer(pcmFormat: outFormat, frameCapacity: 4096)! bufferOut.frameLength = 0 var error: NSError? let status = audioConverter.convert(to: bufferOut, error: &error, withInputFrom: inputBlock) switch status { case .haveData: if verbose { print("✅ convert returned haveData: \(bufferOut.frameLength) frames") } if bufferOut.frameLength > 0 { if bufferOut.isSilent { print("(haveData) SILENT BUFFER at frame \(totalFrames), pending: \(pendingFrames), inputPackets=\(bufferIn.packetCount), outputFrames=\(bufferOut.frameLength)") } outBuffers.append(bufferOut) totalFrames += Int(bufferOut.frameLength) } case .inputRanDry: if verbose { print("🔁 convert returned inputRanDry: \(bufferOut.frameLength) frames") } if bufferOut.frameLength > 0 { if bufferOut.isSilent { print("(inputRanDry) SILENT BUFFER at frame \(totalFrames), pending: \(pendingFrames), inputPackets=\(bufferIn.packetCount), outputFrames=\(bufferOut.frameLength)") } outBuffers.append(bufferOut) totalFrames += Int(bufferOut.frameLength) } return // wait for next handlePackets case .endOfStream: if verbose { print("✅ convert returned endOfStream") } return case .error: if verbose { print("❌ convert returned error") } if let error = error { print("error converting: \(error.localizedDescription)") } return @unknown default: fatalError() } } }

The document-based SwiftUI example app (https://developer.apple.com/documentation/swiftui/building-a-document-based-app-with-swiftui) doesn't specify a launch image. It would seem per the HIG that the "pinkJungle" background in the app would be a decent candidate for a launch image, since it will be in the background when the document browser comes up. However when specifying it as the UIImageName, it is not aligned the same as the background image. I'm having trouble figuring out how it should be aligned to match the image. The launch image seems to be scaled up a bit over scaledToFill. I suppose a launch storyboard might make this more explicit, but I still should be able to do it without one. This is the image when displayed as the launch image: and this is how it's rendered in the background right before the document browser comes up: