my dynamic island UI is triggering as empty when i send my curl, this is a pushToStart run push driven live activity and when i send my curl this is what appears, despite be being able to render the UI through a local push no problem, here is my curl. curl -v \ -H "apns-topic: MuscleMemory.KimchiLabs.com.push-type.liveactivity" \ -H "apns-push-type: liveactivity" \ -H "apns-priority: 10" \ -H "Content-Type: application/json" \ -H "authorization: bearer eyJhbGciOiJFUzI1NiIsImtpZCI6IjI4MjVTNjNEV0IifQ.eyJpc3MiOiJMOTZYUlBCSzQ2IiwiaWF0IjoxNzU4ODU2MDkyfQ.i83VbgROsxEzdgr512iQkVsp0FjHIoHq2L6IB2aL1fImJgX-XM6TM5frNnVyfva7haMd9fDGjO2D_wfCq8WnBg" \ --data '{ "aps": { "timestamp": '"$now"', "event": "start", "content-state": { "plain_text": "hello world", "userContentPage": ["hello world"] }, "attributes-type": "KimchiKit.DynamicRepAttributes", "attributes": { "activityID": "12345" }, "alert": { "title": "Workout started", "body": "We’ll show your reps on the Lock Screen.", "sound": "default" } } }' \ --http2 https://api.sandbox.push.apple.com/3/device/80d50a03472634d9381b729deec58a3e250ea0006b7acd7c2d6ef19e553dcdb010eb1434ff9a6907380f6ed3e9276d57d58f3cda3ac9fc3bea67abae116601a63ec77a34174fd271c4151ec898abae30 and heres my content state which resides in a shared module @available(iOS 17.0, *) public struct DynamicRepAttributes: ActivityAttributes, Codable { public struct ContentState: Codable, Hashable { public var plainText: String public var userContentPage: [String] public enum CodingKeys: String, CodingKey { case plainText = "plain_text" case userContentPage } public init(plainText: String, userContentPage: [String]) { self.plainText = plainText self.userContentPage = userContentPage } } public var activityID: String public init(activityID: String) { self.activityID = activityID } } Ive also alr verified my attributes type is correct, have been stuck on this issue would really appreciate the help

My start live activity CURL is not starting my live activity and I keep getting a decoding failure even though my curl matches my content state so my live activity is not starting. heres my CURL --header "apns-topic: MuscleMemory.KimchiLabs.com.push-type.liveactivity" \ --header "apns-push-type: liveactivity" \ --header "apns-priority: 10" \ --header "authorization: bearer eyJhbGciOiJFUzI1NiIsImtpZCI6IjI4MjVTNjNEV0IifQ.eyJpc3MiOiJMOTZYUlBCSzQ2IiwiaWF0IjoxNzU3NDYwMzQ2fQ.5TGvDRk5ZYLsvncjKwXIZYN78X88v5lCwX4fRvfl1QXjwv8tOtO2uoId27LQahXA3zqjruu_2YoOfqEtrppKXQ" \ --data '{ "aps": { "timestamp": '"$(date +%s)"', "event": "start", "content-state": { "plain_text": "hello world", "userContentPage": ["hello world"] }, "alert": { "sound": "chime.aiff" } }, "attributes-type": "KimchiKit.DynamicRepAttributes", "attributes": {} }' \ --http2 https://api.sandbox.push.apple.com/3/device/802fe7b4066e26b51ede7188a7077a9603507a0fa6ee8ffda946a864e75aa139602861538d6fb12100afbe9a3338d6c7c799d947dfacb2ee835f0339ecdc3165c9ed7e54839f5a3b89b76a011f5826cc and here is my content state public struct ContentState: Codable, Hashable { public var plainText: String public var userContentPage: [String] public enum CodingKeys: String, CodingKey { case plainText = "plain_text" case userContentPage } public init(plainText: String, userContentPage: [String]) { self.plainText = plainText self.userContentPage = userContentPage } } public init() {} }

Hi, I'm having this issue that I have have not been able to figure out as I've gone through a checklist and it seems I have everything in place, but im sending my pushToStartTokenUpdates token to a server and im able to test starting a live activity via CURL where it shows my push token going through and even my test payload but after a while I get this issue in my logs where it fails to find a live activity Push notifications are set up, im sending my token to APN and im even able to start live activities locally.

i finally got previews for dynamic island to work and I'm just trying to first work on adding a static UI elements to my dynamic island like i did for my live screen live activity, but my dynamic island view is showing up totally empty, if i add my app icon image to the compact leading closure, it doesn't appear, if i ad text to an expanded region closure it doesn't appear. am really stuck on this and would approeciate the help. var body: some View { Image("dynamicrep") .resizable() .scaledToFit() .clipShape(.circle) } } struct DynamicRepLiveActivity: Widget { var body: some WidgetConfiguration { ActivityConfiguration(for: DynamicRepAttributes.self) { context in VStack { HStack(spacing: 257) { Text("from \(context.attributes.titleName ?? "no title")") .fontWeight(.light) .font(.system(size: 16)) .foregroundStyle(Color.gray) Circle() .frame(width: 53, height: 50) .foregroundStyle(Color.gray).opacity(0.23) .overlay { Image("mmicon") } } .frame(maxWidth: 500, maxHeight: 210) Spacer() Text("\(context.attributes.contentBody ?? "no content")") } .activityBackgroundTint(Color.cyan) .activitySystemActionForegroundColor(Color.black) .frame(width: 500, height: 300) } dynamicIsland: { context in DynamicIsland { // Expanded UI goes here. Compose the expanded UI through // various regions, like leading/trailing/center/bottom DynamicIslandExpandedRegion(.leading) { Text("from \(context.attributes.titleName ?? "no title")") } DynamicIslandExpandedRegion(.trailing) { Circle() } DynamicIslandExpandedRegion(.bottom) { Text("\(context.attributes.contentBody ?? "no content")") } } compactLeading: { AppLogo() } compactTrailing: { Text("") //empty for now } minimal: { Text("hello") //empty for now } .widgetURL(URL(string: "MuscleMemory.KimchiLabs.com")) .keylineTint(Color.white) } } }

Hello, I have a small lightweight macOS application that includes a medium widget but the widget does not update with new data as often as I'd like. I understand that in apple's WidgetKit documentation they mention that apple controls when the widget updates due to battery life concerns, but I'd like to know if theres any way at all to control when the widget updates or when I think it makes sense to do so if I am not able to control how often it refreshes new data. https://github.com/Alexx1105/MacStat-v2.1

Im building a macOS application where the UI is a blurry transparent background that is somewhat see through like what apple uses for the macOS control center and I'm using the NSVisualEffectView from AppKit to do so. My question is, does the Xcode simulator accurately portray translucent UI views? in other words: "what you see is what you get" or will the vibrancy be more pronounced when the app is run on my machine itself. var material: NSVisualEffectView.Material = .contentBackground //blurry background to cover the whole UI var blendUI: NSVisualEffectView.BlendingMode = .behindWindow // applying the blurry background to the UI window itself var allowsVibrancy: Bool = true func makeNSView(context: Context) -> NSVisualEffectView { let blurryEffectView = NSVisualEffectView() blurryEffectView.material = material blurryEffectView.blendingMode = blendUI return NSVisualEffectView() } func updateNSView(_ nsView: NSVisualEffectView, context: Context) { // _ added, no argument label needed nsView.material = .contentBackground nsView.blendingMode = blendUI } } struct ContentView: View { var body: some View { ZStack{ EffectView(material: NSVisualEffectView.Material.contentBackground, blendUI: NSVisualEffectView.BlendingMode.behindWindow ) } } }

I know this is a more abnormal question to ask on this forum but I really would like to gauge feedback from a community of other Swift developers on an idea. A colleague and I are seriously considering building a open-source web based SwiftUI component catalog that feature a collection of prebuilt modular components very similar to Shadcn for those of you who have worked in React but for SwiftUI where you can also contribute your own SwiftUI elements. Im curious if this would be something iOS/Swift devs would be possibly interested in and would love to hear thoughts on this idea. This is not a component library as Xcode technically has one thats built in, but rather fully built out SwiftUI elements such as UIs that use glass morphism for macOS, calendars for iOS apps, charts, etc.

I have backend API caller file that retrieves and displays unwrapped JSON data via URLRequest(). All the data is printed to my console when I build the project but it's not being displayed in the actual UI of my iOS simulator. I have a class in my ContentView that updates the UI and filters the extracted fields shown here below: class NotionCall: ObservableObject { @Published var extractedContent: [BlockBody.Block] = [] func makeAPIRequest() { makeRequest { results in let extractedData = results.map { block -> BlockBody.Block in var extractedBlock = block extractedBlock.ExtractedFields = block.paragraph?.textFields.compactMap { textField in textField.PlainText ?? textField.RichText ?? textField.content //iterate over PlainText, RichText, and Content fields and return the non nill values } ?? [] //validate objects even if they are nil return extractedBlock } DispatchQueue.main.async { self.extractedContent = extractedData } } } } @StateObject var NotionCaller = NotionCall() //manage lifecycle of instance And then below here is my SwiftUI structure that contains List(NotionCaller.extractedContent) { block in ForEach(block.ExtractedFields, id: \.self) { field in Text(field) meant to display the extracted data to the UI: var body: some View { NavigationStack { ZStack { List(NotionCaller.extractedContent) { block in ForEach(block.ExtractedFields, id: \.self) { field in Text(field) } } ZStack { Color(hex: "#f9f9f9") .ignoresSafeArea() VStack { TextField(" Search keywords", text: $searchKeywords) //change font later .frame(height: 48) .overlay(RoundedRectangle(cornerRadius: 30).strokeBorder(style: StrokeStyle())) .foregroundColor(.white) .background(.white) .cornerRadius(30) .padding() .scaledToFit() .frame(maxHeight: .infinity, alignment: .top) } VStack { Spacer() Divider() .padding() HStack { Button(action: { //add functionality later }) { Image("menuButton") .frame(alignment: .bottom) .padding(.horizontal, 42) Spacer() } HStack { Button(action: { //add functionality later }) { Image("notificationButton") .frame(alignment: .leading) .padding(.leading, 30) Spacer() } } HStack { Button(action: { }) { Image("notionImportButton") .frame( alignment: .trailing) .padding(.horizontal) .padding(.horizontal) } } } .onAppear { NotionCaller.makeAPIRequest() } } } } } } }

I have a bunch of JSOn data printed to my console but I want that data to be displayed in my UI on the iOS simulator and content view UI. ill show the class with my instances and property wrapper im using aswell as the function thats calling my other code that displays the data in the console @Published var makeapirequest: String = "" //make sure instance is correct func makeAPIRequest() { makeRequest() } } @StateObject public var NotionCaller = NotionCall() //manage lifecycle of instance and then below is the Text() line I added the display the data aswell as the onAppear modifier NotionCaller.makeAPIRequest() } Text(NotionCaller.makeapirequest) im trying to display the data by calling the instance of the function that calls makeRequest() but the data is still being displayed in the console rather than in my swiftUI.

Im making an API call using notions API to access and retrieve data from my Notion page and I'm successfully making the url request and accessing the page, however I seem to be struggling with returning the actual data that I have in that page and parsing the JSON data as right now, my console only outputs the makeup of my notion page rather than the formatted and parsed data. I made a codable struct meant to replicate the structure of a notion page based off their documentation then I'm passing that struct to my JSON parsing function but my data still is not being parsed and returned. heres what I have. import Foundation struct Page: Codable, Hashable { //Codable struct for notion "Page" for defining content aswell as object representation in a codable struct of all the basic components that make up a notion page per notion's documentation let created_time: String let created_by: String let last_edited_time: String let object: String let cover: String let emoji: String let icon: String struct properties: Codable, Hashable { let title: String let dueDate: String let status: String } struct dueDate: Codable, Hashable { let id: String let type: String let date: String let start: String let end: String? //optionals added to "end" and "time_zone" as these values are set to null in the documentation let time_zone: String? } struct Title: Codable,Hashable { let id: String let type: String let title: [String] } struct annotations: Codable, Hashable { let bold: Bool let italic: Bool let strikethrough: Bool let underline: Bool let code: Bool let color: String } let English: String let Korean: String let Pronounciation: String let in_trash: Bool let public_url: String? let annotations: Bool } let url = URL(string: "https://api.notion.com/v1/pages/8efc0ca3d9cc44fbb1f34383b794b817") let apiKey = "secret_Olc3LXnpDW6gI8o0Eu11lQr2krU4b870ryjFPJGCZs4" let session = URLSession.shared func makeRequest() { if let url = url { var request = URLRequest(url: url) let header = "Bearer " + apiKey //authorization header declaration request.addValue(header, forHTTPHeaderField: "authorization") //append apikey request.addValue("2022-06-28",forHTTPHeaderField: "Notion-Version") //specify version per notions requirments let task = URLSession.shared.dataTask(with: request) { data, response, error in if let httpError = error { print("could not establish HTTP connection:\(httpError)") } else { if let httpResponse = response as? HTTPURLResponse { if httpResponse.statusCode == 200 { } else { print("invalid api key:\(httpResponse.statusCode)") } } } if let unwrapData = data { //safely unwrapping the data value using if let if let makeString = String(data: unwrapData, encoding: .utf8) { print(makeString) } else { print("no data is being returned:") } do { let decoder = JSONDecoder() //JSONDecoder method to decode api data, let codeUnwrappedData = try decoder.decode(Page.self,from: unwrapData) //Page. specifies its a struct, from: passes the data parmeter that contains the api data to be decoded //PASS STRUCTURESDATABASE STRUCT print("data:\(codeUnwrappedData)") } catch { print("could not parse json data") } if let httpResponse = response as? HTTPURLResponse { if httpResponse.statusCode == 200 { print(String(data: unwrapData, encoding: .utf8)!) } else { print("unsuccessful http response:\(httpResponse)") } } } } task.resume() } }

Im using Notions API to print out some data from one of my own pages in notion and im using URLSession to make the request then parsing the unwrapped data but nothing is being returned to my console and I know my endpoint and API key is correct. I've gone through the notion API documentation can't can't seem to find anything in it that I am not doing or doing wrong. Ill provide my code as well as the documentation I've been consulting: https://developers.notion.com/reference/intro import Foundation struct Page: Codable { let id: String let title: String } let endpoint = URL(string: "https://api.notion.com/v1/pages/8efc0ca3d9cc44fbb1f34383b794b817") let apiKey = "… redacted …" let session = URLSession.shared func makeRequest() { if let endpoint = endpoint { let task = URLSession.shared.dataTask(with: endpoint) { data, response, error in if let taskError = error { print("could not establish url request:\(taskError)") return } if let unwrapData = data { //safely unwrapping the data value using if let do { let decoder = JSONDecoder() //JSONDecoder method to decode api data, let codeUnwrappedData = try decoder.decode(Page.self,from: unwrapData) //type: specifies its a struct, from: passes the data parmeter that contains the api data to be decoded } catch { print("could not parse json data") } } if let httpResponse = response as? HTTPURLResponse { if httpResponse.statusCode == 200 { if let apiData = data { print(String(data: apiData, encoding: .utf8)!) } } else { print("unsuccessful http response:\(httpResponse)") } makeRequest() } } task.resume() } }

I have an async function where im using the withUnsafeContinuation method and closure but for some reason Xcode is not letting me pass either 'error' or 'Error' for continuation.resume(throwing:). I get the error "Cannot convert value of type 'any Error'" public func parseResponseData(data: Data) async throws -> TextResult { return try await withUnsafeContinuation { continuation in Task { do { let decoder = JSONDecoder() let result = try await decoder.decode(TextResult.self, from: data) continuation.resume(returning: result) } catch { continuation.resume(throwing: error) } } } }

I have some c code that returns memory usage of a current task on my machine and recently redacted it to use the proc_getallinfio struct so I can instead retrieve systemwide memory usage. im calling that code in swift however im getting the error "Initializer 'init(_:)' requires that 'proc_taskallinfo' conform to 'BinaryInteger'" and im not sure what the appropriate field is to pass that works with proc_getallinfo struct. resident_size does not work in this context. import IOKit import Foundation @_silgen_name("kernMem") func kernMem(storeMemData: UnsafeMutablePointer <proc_taskallinfo>) -> kern_return_t @main struct MacStatAppApp: App { @State public var printMemory: String = "" //dynamic state object to store data that will be passed to swiftUI var body: some Scene { WindowGroup { ContentView(printMemory: $printMemory) //binding for printMemory to pass data to contentview .onAppear { var storeMemData = proc_taskallinfo() //define pointer let result = kernMem(storeMemData: &storeMemData) if result == KERN_SUCCESS { let memoryUsage = Double(storeMemData) / (1024.0 * 1024.0 * 1024.0) //conversion for GB, 1024 to the power of 3 print(String(format: "memory usage: %.2f GB", memoryUsage)) } else { print("failed to obtain memory usage data:\(result)") } } } } }

Im honestly a bit lost and looking for general pointers. Here is the general flow of my project. I have an Xcode project where I want to return and convert the temperature values accessed from the apple smc and I found a GitHub repo with all the smc key sensors for the M3Pros/Max chips: https://github.com/exelban/stats/issues/1703 basically, I have all these keys stored in an array in obj-c like so: NSArray *smcKeys = @[ @"Tp01", @"Tp05", @"Tp09", @"Tp0D", @"Tp0b", @"Tp0f", @"Tp0j", @"Tp0n",@"Tp0h", @"Tp0L", @"Tp0S", @"Tp0V", @"Tp0z", @"Tp0v", @"Tp17", @"Tp1F", @"Tp1J", @"Tp1p", @"Tp1h", @"Tp1R", ]; I am passing all these keys by passing 'smcKeys' in a regular C code file I have here that is meant to open, close and read the data shown here: #include "smc.h" #include <mach/mach.h> #include <IOKit/IOKitLib.h> #include "smckeys.h" io_connect_t conn; kern_return_t openSMC(void) { kern_return_t result; kern_return_t service; io_iterator_t iterator; service = IOServiceGetMatchingServices(kIOMainPortDefault, IOServiceMatching("AppleSMC"), &iterator); if(service == 0) { printf("error: could not match dictionary"); return 0; } result = IOServiceOpen(service, mach_task_self(), 0, &conn); IOObjectRelease(service); return 0; } kern_return_t closeSMC(void) { return IOServiceClose(conn); } kern_return_t readSMC(char *smcKeys, SMCVal_t *val) { kern_return_t result; uint32_t keyCode = *(uint32_t *)smcKeys; SMCVal_t inputStruct; SMCVal_t outputStruct; inputStruct.datasize = sizeof(SMCVal_t); inputStruct.datatype = 'I' << 24; //a left shift operation. turning the I into an int by shifting the ASCII value 24 bits to the left inputStruct.data[0] = keyCode; result = IOConnectCallStructMethod(conn, 5, &inputStruct, sizeof(SMCVal_t), &outputStruct, (size_t*)&inputStruct.datasize); if (result == kIOReturnSuccess) { if (val -> datasize > 0) { if (val -> datatype == ('f' << 24 | 'l' << 16 | 't' << 8 )) { //bit shifting to from 32bit operation associated with the ASCII charecters'f', 'l', and 't', sets datatype field. double temp = *(double *)val -> data; return temp; } } } return 0.0; } Which I am then then calling the functions from this file in a swift file and converting the values to Fahrenheit but no data is being printed in my console: import IOKit public class getTemperature { public struct SMCVal_t { var datasize: UInt32 var datatype: UInt32 var data: (UInt8, UInt8, UInt8, UInt8, UInt8, UInt8, UInt8, UInt8) } @_silgen_name("openSMC") func openSMC() -> kern_return_t @_silgen_name("closeSMC") func closeSMC() -> kern_return_t @_silgen_name("readSMC") func readSMC(key: UnsafePointer<CChar>?,val: UnsafeMutablePointer<SMCVal_t>) -> kern_return_t func convertAndPrintTempValue(key:UnsafePointer<CChar>?,scale: Character, showTemp: Bool ) -> kern_return_t { let openSM = openSMC() guard openSM == 0 else { print("Failed to open SMC: \(openSM)") return kern_return_t() } let closeSM = closeSMC() guard closeSM == 0 else { print("could not close SMC: \(closeSM)") return IOServiceClose(conn) } func convertAndPrint(val: SMCVal_t) -> Double { if val.datatype == (UInt32("f".utf8.first!) << 24 | UInt32("l".utf8.first!) << 16 | UInt32("t".utf8.first!) << 8) { let extractedTemp = Double(val.data.0) return( extractedTemp * 9.0 / 5.0 + 32.0 ) } return 0.0 } let smcValue = SMCVal_t(datasize: 0, datatype: 0, data: (0,0,0,0,0,0,0,0)) let convertedVal = convertAndPrint(val: smcValue) print("Temperarure:\(convertedVal)F°") return kern_return_t() } } I know this is a lot but I am honestly looking for any tips to fill in any gaps in my knowledge for anyone who's built a similar application meant to extract any sort of data from Mac hardware.

I have an Xcode project with an obj-c .c file and a .h file aswell as a .swift file where I am calling functions from those obj-c files with a bridging header but when I build my project I get a duplicate symbols error and Xcode doesn't show where. here is .h header file: #define smc_h #include &lt;stdint.h&gt; #include &lt;mach/mach.h&gt; #include &lt;IOKit/IOKitLib.h&gt; typedef struct { uint32_t datasize; uint32_t datatype; uint8_t data[8]; } SMCVal_t; io_connect_t conn; kern_return_t openSMC(void); kern_return_t closeSMC(void); kern_return_t readSMC(char *key, SMCVal_t *val); double convertToFahrenheit(SMCVal_t *val); #endif /* smc_h */ my .c implementation file: #include "smc.h" kern_return_t openSMC(void) { kern_return_t result; kern_return_t service; io_iterator_t iterator; service = IOServiceGetMatchingServices(kIOMainPortDefault, IOServiceMatching("AppleSMC"), &amp;iterator); if(service == 0) { printf("error: could not match dictionary"); return 0; } result = IOServiceOpen(service, mach_task_self(), 0, &amp;conn); IOObjectRelease(service); return 0; } kern_return_t closeSMC(void) { return IOServiceClose(conn); } kern_return_t readSMC(char *key, SMCVal_t *val) { kern_return_t result; uint32_t keyCode = *(uint32_t *)key; SMCVal_t inputStruct; SMCVal_t outputStruct; inputStruct.datasize = sizeof(SMCVal_t); inputStruct.datatype = 'I' &lt;&lt; 24; //a left shift operation. turning the I into an int by shifting the ASCII value 24 bits to the left inputStruct.data[0] = keyCode; result = IOConnectCallStructMethod(conn, 5, &amp;inputStruct, sizeof(SMCVal_t), &amp;outputStruct, (size_t*)&amp;inputStruct.datasize); if (result == kIOReturnSuccess) { if (val -&gt; datasize &gt; 0) { if (val -&gt; datatype == ('f' &lt;&lt; 24 | 'l' &lt;&lt; 16 | 't' &lt;&lt; 8 )) { //bit shifting to from 32bit operation associated with the ASCII charecters'f', 'l', and 't', sets datatype field. double temp = *(double *)val -&gt; data; return temp; } } } return 0.0; } double convertToFahrenheit(SMCVal_t *val) { if(val -&gt; datatype == ('f' &lt;&lt; 24 | 'l' &lt;&lt; 16 | 't' &lt;&lt; 8 )) { //checking if val-&gt;datatype is equal to the result of the bit-shifting operation. double temp = *(double *)val -&gt; data; return (temp * 9.0 / 5.0) + 32.0; } return 0.0; } And my .swift file where my objc functions are called: import IOKit public class CPUTempCaller { public struct SMCVal_t { var datasize: UInt32 var datatype: UInt32 var data: (UInt8, UInt8, UInt8, UInt8, UInt8, UInt8, UInt8, UInt8) } @_silgen_name("openSMC") func openSMC() -&gt; Int32 @_silgen_name("closeSMC") func closeSMC() -&gt; Int32 @_silgen_name("readSMC") func readSMC(key: UnsafePointer&lt;CChar&gt;?,val: UnsafeMutablePointer&lt;SMCVal_t&gt;) -&gt; kern_return_t @_silgen_name("convertToFahrenheit") func convertToFahrenheit(val: UnsafePointer&lt;SMCVal_t&gt;) -&gt; Double { let openSM = openSMC() guard openSM == 0 else { print("Failed to open SMC: \(openSM)") return 0.0; } let closeSM = closeSMC() guard closeSM == 0 else { print("could not close SMC: \(closeSM)") return 0.0; } func convertAndPrintTempValue(key:UnsafePointer&lt;CChar&gt;?,scale: Character, showTemp: Bool ) -&gt; Double? { var SMCValue = SMCVal_t(datasize: 0, datatype: 0, data:(0,0,0,0,0,0,0,0)) //initializing SMC value if let Key = key { //check if nil. If not nil, proceed to code block execution let key = "TC0P" let keyCString = (key as NSString).utf8String //passing key as null terminated utf8 string let readSMCResult = readSMC(key: keyCString, val: &amp;SMCValue) //call readSMC obj-C function, store result in "readSMCResult" if readSMCResult != KERN_SUCCESS { print("Failed to read SMC: \(readSMCResult)") } } if showTemp { //return nil if showTemp is false let convertRawToFahrenheit = convertToFahrenheit(val: &amp;SMCValue) let scaleToStr = String(scale) print(String(format: "Temperature: %0.1f °%c", convertRawToFahrenheit, scaleToStr)) return nil } else { print("could not convert temperature and format values in Fahrenheit") return nil } } return 0.0; } }