External Accessory

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Communicate with accessories connected to a device by the Apple Lightning connector or through Bluetooth using External Accessory.

Posts under External Accessory tag

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EASession(accessory:forProtocol:) always returns nil — MFI accessory iAP2
EASession(accessory:forProtocol:) always returns nil — MFI accessory iAP2 Platform: iOS 17+ | Hardware: Custom MFI-certified accessory (USB-C, iAP2) | Language: Swift Problem We have a custom MFI-certified accessory communicating over USB-C using ExternalAccessory. The app calls EASession(accessory:forProtocol:) after receiving EAAccessoryDidConnect but it always returns nil. We never get past session creation. What we have verified We captured a sysdiagnose on-device and analysed the accessoryd-packets log. The full iAP2 handshake completes successfully at the OS level: USB attach succeeds MFI auth certificate is present and Apple-issued Auth challenge and response complete successfully IdentificationInformation is accepted by iOS — protocol string and Team ID are correct EAAccessoryDidConnect fires as expected iOS sends StartExternalAccessoryProtocolSession — the OS-level session is established So the hardware, MFI auth, protocol string, and Team ID are all correct. Despite this, EASession(accessory:forProtocol:) returns nil in the app. We also confirmed: Protocol string in UISupportedExternalAccessoryProtocols in Info.plist matches the accessory exactly Protocol string in code matches Info.plist App entitlements are correctly configured EAAccessoryManager.shared().registerForLocalNotifications() is called before connection Current connection code @objc private func accessoryDidConnect(_ notification: Notification) { guard let accessory = notification.userInfo?[EAAccessoryKey] as? EAAccessory else { return } DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) { self.tryConnectToAccessory() } } private func tryConnectToAccessory() { DispatchQueue.main.asyncAfter(deadline: .now() + 3.0) { for accessory in EAAccessoryManager.shared().connectedAccessories { let session = EASession(accessory: accessory, forProtocol: "") // session is always nil here } } } Questions The packet log shows a ~4 second gap between EAAccessoryDidConnect firing and iOS internally completing session readiness (StartExternalAccessoryProtocolSession). Is there a reliable way to know when iOS Is it actually ready to grant an EASession, rather than using a fixed delay? Is there a delegate callback or notification that fires when the accessory protocol session is ready to be opened, rather than relying on EAAccessoryDidConnect + an arbitrary delay? Are there any known conditions on iOS 17+ under which EASession returns nil even though the iAP2 handshake completed successfully at the OS level? Is retrying EASession after a nil result a supported pattern, or does a nil result mean the session will never succeed for that connection? Any guidance appreciated.
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We are currently developing a FindMy device and we're wondering how to use UWB ranging functionality in the "Find My" app.
目前这个findmy 设备是已经通过MFI认证,不过后续想的在”Find My “应用上像 AirTag 一样支持UWB测距功能。 寻找了相关资料,在这篇文章《Nearby-Interaction-Accessory-Protocol-Specification-Release-R4》中找到了UWB的相关功能,但是需要我们自己开发第三方应用。 所以需要怎么做才可以做到像airtag 一样在“Find My”应用上显示距离和方向
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We are currently developing a FindMy device and we're wondering how to use UWB ranging functionality in the "Find My" app.
The FindMy device is currently MFI certified, but we plan to support UWB ranging functionality in the Find My app, similar to AirTag. After searching for relevant information, I found the relevant UWB functions in this article "Nearby-Interaction-Accessory-Protocol-Specification-Release-R4", but we need to develop third-party applications ourselves. So how can we make it display distance and direction in the "Find My" app like AirTag does?
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UVC over MFi – Is there official support? Implementation guidance?
Hello everyone, I’m looking for more detailed information regarding UVC (USB Video Class) over MFi within the Apple ecosystem and would appreciate some clarification. I’m interested in developing (or interfacing with) an accessory that transmits video over USB using the UVC standard, and I’d like to better understand how this works within the MFi (Made for iPhone) program. Here are my main questions: 1. Do iOS devices provide native support for UVC over USB-C or Lightning within the MFi framework? 2. Are there any specific firmware or authentication requirements when the accessory is MFi-certified? 3. Does UVC support depend solely on the hardware interface (USB-C vs Lightning), or are there additional software-level requirements? 4. Is there any official documentation outlining the recommended flow for implementing UVC-based video capture accessories on iOS? From what I understand, USB-C iPads appear to offer more direct support for standard UVC devices, but it’s not entirely clear how this integrates with the MFi ecosystem with iOS, especially for commercial product development. If anyone has gone through this process or can point me to relevant technical documentation, I would greatly appreciate the guidance. Thank you!
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External Keyboard DatePicker Issues
I am currently trying to get my app ready for full external keyboard support, while testing I found an issue with the native DatePicker. Whenever I enter the DatePicker with an external keyboard it only jumps to the time picker and I am not able to move away from it. Arrow keys don't work, tab and control + tab only move me to the toolbar and back. This is how they look like private var datePicker: some View { DatePicker( "", selection: date, in: minDate..., displayedComponents: [.date] ) .fixedSize() .accessibilityIdentifier("\(datePickerLabel).DatePicker") } private var timePicker: some View { DatePicker( "", selection: date, in: minDate..., displayedComponents: [.hourAndMinute] ) .fixedSize() .accessibilityIdentifier("\(datePickerLabel).TimePicker") } private var datePickerLabelView: some View { Text(datePickerLabel.localizedString) .accessibilityIdentifier(datePickerLabel) } And we implement it like this in the view: HStack { datePickerLabelView Spacer() datePicker timePicker } Does anyone know how to fix this behavior? Is it our fault or is it the system? The issue comes up both in iOS 18 and 26.
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Feb ’26
Is it safe to run Xcode from an external drive?
I’m currently facing a disk space limitation on my Mac. I’ve already freed up some storage by following the suggestions shared in a previous post, which helped partially, but the issue is not fully resolved and space is still a bottleneck for my workflow. To move forward, I’d like to ask a very concrete question: Is it safe and supported to move Xcode to an external hard drive (SSD), use it from there, and simply connect the drive whenever I need to work with Xcode? Specifically: Are there known issues with performance, stability, or updates? Are there components that must remain on the internal disk to avoid unexpected behavior? Is this a reasonable long-term setup, or just a temporary workaround? I want to make sure I’m not setting myself up for hidden problems down the road. Thanks in advance for any clarification or best practices you can share.
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Jan ’26
iPhone17 (iOS26) BLE connection issue (MTU, Primary Service)
I'm developing an App that works with BLE connection based devices. The BLE connection process, which connects well to the iPhone 16 without any problems, has not worked at all since the iPhone 17. Even when using the same iOS26 version, iPhone 17 is the only one having problems. Progress is stuck after frame 124 in the entire snoop below. Please check if it is a known problem or if there is a solution. 123 2025-11-04 02:01:39.262000 0.000000 localhost () 7c:c6:b6:91:10:04 () ATT 12 Sent Exchange MTU Response, Server Rx MTU: 232 124 2025-11-04 02:01:39.265000 0.003000 localhost () 7c:c6:b6:91:10:04 () ATT 16 Sent Read By Group Type Request, GATT Primary Service Declaration, Handles: 0x0001..0xffff
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Nov ’25
Custom USB Network Device Driver on iPhone
Hi, We are using the AX88772C as a USB->Ethernet bridge in a product we are developing. Due to the chip not following the NCM protocol, it is not supported by the default networking drivers on the iPhone. Initially, we intended on using DriverKit to develop a userspace driver for this device. However, we have been informed DriverKit is only available on iPad OS, not iOS. As such is the case, we have found two possible alternatives. First being IOkit, and the second being External Accessory Session (EASession). What are the limitations of each of these options? We need the ability to send and receive USB packets to Control and Bulk endpoints. Is this possible with either of the options defined above? Would either of these options require the device to be MFi certified? We have read that some APIs within IOkit require the apple device to be jailbroken. Is there a list of features that can be used without a jailbroken device? Documentation on these 2 options is limited, so any official documentation would be great. Thanks!
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Oct ’25
HELP ME
HELP ME someone is using all of these tools etc and have been hacking all of my devices and iClouds and certain apps using HomeKit iCloud kit Xcode and I need someone to help me debug my phone or teach me what to do they are using hardware or external / sharing across devices / and it’s seriously affecting my physical and mental health. I have contacted the FBI and have a meeting in October but I’m hoping someone can help me in the time being please it’s all of my devices and daugters tabelts / doesn’t matter if it’s android or iPhone . help plssss
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Sep ’25
EAWiFiUnconfiguredAccessoryBrowser "Accessory Setup" UI selects blank/null SSID by default
We've received several reports of a new bug while setting up our products with WAC. The Accessory Setup UI appears with a blank network selected and the message 'This accessory will be set up to join "(null)".' at top. The user can tap "Show Other Networks..." to select another network, but this experience is very confusing. Why does this UI present a choice that is known to be invalid when other valid choices exist? I've captured a screenshot and sysdiagnose from this case. In most cases this problem happens only intermittently, but I can reproduce it consistently by disconnecting my iPhone from any WiFi network (WiFi remains enabled). My suggestion for a better user experience is that this UI should select the default network according to these rules: The network to which iPhone is currently connected. Any network which is in the known/my list for this iPhone Any valid network I believe rule #1 is the existing behavior, but applying rules #2 and #3 as fallbacks would be an improvement. Is there anything I can change in my iOS code or in my accessory's WAC server to improve this experience?
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Sep ’25
Stay connected to Medical BLE device in background
I work for a large medical device company. We have a 1st party BLE enabled medical device that must be very battery efficient. To this end, if a connection is lost, the BLE radio is powered down after 60 seconds and will only turn back on when a physical button on the device is pressed. I've been tasked with connecting to the device, staying connected to the device, and being able to retrieve data from the device upon a timed action. For instance, this could include a data read and transmission while they sleep. The key part of this is staying reliably connected for extended periods of time. This is a BYOD setup, and we cannot control power profiles. I would very much appreciate any information, recommendations, and/or insights into solving this problem. Thanks!
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Sep ’25
HomeKit ADK Remote.OpenSSL fails with No setup info found in key-value store during pairing (HAPPlatformAccessorySetup.c:93)
Hello Apple Developers, I'm currently working on building a custom HomeKit Accessory using the HomeKit ADK v6.3 and running the Remote.OpenSSL sample on a Raspberry Pi 4 (64-bit Ubuntu / Linux Kernel 6.1.21-v8+). I'm trying to pair the accessory via the MFi HomeKit ADK pairing process. I've successfully compiled the ADK using: The application (Remote.OpenSSL) launches correctly, and the accessory server starts as expected, broadcasting via mDNS. However, when I attempt to initiate pairing via iOS (or simulate pairing), the following error occurs: Fault fatal error - HAPPlatformAccessorySetupLoadSetupInfo @ PAL/Linux/HAPPlatformAccessorySetup.c:93 This causes the application to crash.
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Jul ’25
External Accessory
Hi, we are listed for the MFI program as a licensed manufacturer. We have now started with the IAP3 sample code and the IAP chips to build up a USB communication between our accessory and an iOS device. We are looking for a sample project for the iOS part. Is there some available? The only official I can find is this: https://developer.apple.com/library/archive/samplecode/EADemo/Introduction/Intro.html#//apple_ref/doc/uid/DTS40010079 This app is somehow outdated and from 2016. Is there something else available as a starting point? And how does this relate to IOKit since it is available for serial communication on iOS16 as well? Kind regards,
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Jul ’25
Verifying braille output in an iOS app without a physical braille device?
I'm developing a calculator app and working to ensure a great experience for both VoiceOver and Braille display users. For expressions like (2+3)×5, I need two different accessibility outputs: VoiceOver (spoken): A descriptive string like “left paren two plus three right paren times five,” provided via .accessibilityValue. I'm using a custom spellOut function since VoiceOver doesn't announce parentheses—which are kind of important when doing math! Braille (symbolic): The literal math string (2+3)×5, provided using .accessibilityCustomContent("", ...), with an empty label so it’s not spoken aloud. The issue: I don’t have access to a Braille display device and Xcode’s Accessibility Inspector doesn’t seem to show the custom content. Is there any way to confirm that custom Braille content is being set correctly in Simulator or with other tools? Or…is there a "math mode" in VoiceOver that forces it to announce parentheses? Any advice or workarounds would be much appreciated! Thanks, Uhl
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Jul ’25
What kind of feedback is available through tvOS Bluetooth HID?
first post here and this is kinda a long shot. I’m working on a custom keypad project for a young man with some mobility issues that unfortunately prevents gestrue and voice control as UI options. id like to see if I can pull track metadata via a Bluetooth connection into a custom keyboard with a small screen. I know hid doesn’t support this but I was hoping maybe the API for iOS’s blueprint remote app could be leveraged. I haven’t don’t much with Apple previousl. Usually Roku and Crestron implantations but I’m hoping to see if I can accomplish something with Apple, without needing to implement any IP connection.
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Jul ’25
Example for AccessorySetupKit bluetoothTransportBriding
Hi there! I'm developing a dual-mode bluetooth accessory and would like to pair it through AccessorySetupKit. I'm using an ESP32 with Bluekitchen btstack. This supports CTKD, which seems to be a requirement for the Bluetooth transport bridging according the WWDC19 session 901. I've been in contact with the btstack developer and verified that I can get the device to generate an LTK for the classic transport when reading an encrypted attribute. I'm not able to get this to work with the bluetoothTransportBriding option with AccessorySetupKit though. What I've found so far is that if I omit the .bluetoothTransportBriding option during pairing I will get a pairing request when I read an encrypted attribute after connecting with the CBConnectPeripheralOptionEnableTransportBridgingKey option. If I accept this request it seems like the system automatically brings up the A2DP profile. However if I include .bluetoothTransportBriding and/or .bluetoothPairingLE this option does not pop up, but the system does not bring up the A2DP profile. In this case things seem to end up in a weird situation where the device doesn't show up for pairing in Bluetooth Settings either, making it impossible to manually connect for A2DP. Based on the AccessorySetupKit example from WWDC24 I've created a dice accessory firmware for ESP32 using btstack. The code for this is available here: https://github.com/ljodal/esp32-btstack-ctkd-test I've also tweaked the AccessorySetupKit example app for iOS to add the ASAccessory.SupportOptions. The code for that is available here: https://github.com/ljodal/accessorysetupkit-ctkd-test Is there any documentation available anywhere on what is expected of the device for Bluetooth Transport Bridging to work with AccessorySetupKit?
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Jul ’25
Wi-Fi Access Point Not Reconnecting While AVAudioSession Is Active
We’ve encountered a reproducible issue where the iPhone fails to reconnect to a Wi-Fi access point under the following conditions: The device is connected to a 2.4GHz Wi-Fi network. A Bluetooth audio accessory is connected (e.g. headset). AVAudioSession is active (such as during a voice call or when using the Voice Memos app). The user moves away from the access point, causing a disconnect. Upon returning within range, the access point is no longer recognized or reconnected while AVAudioSession remains active. However, if the Bluetooth device is disconnected or the AVAudioSession is deactivated, the Wi-Fi access point is immediately recognized again. We confirmed this behavior not only in my app but also using Apple's built-in Voice Memos app, suggesting this is not specific to our implementation. It appears that the Wi-Fi system deprioritizes reconnection while AVAudioSession is engaged. Could this be by design? Or is this a known issue or limitation with Wi-Fi and AVAudioSession interaction? Test Environment: Device: iPhone 13 mini iOS: 17.5.1 Wi-Fi: 2.4GHz band Accessories: Bluetooth headset We’d appreciate clarification on whether this is expected behavior or a bug. Thank you!
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Jun ’25