IOBluetooth

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Gain user-space access to Bluetooth devices using IOBluetooth.

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BLE audio packet loss on iPhone 17 (Bluetooth 6 / N1) in real-time streaming
Hello Apple Bluetooth team, We are developing a real-time call translation system that streams raw PCM audio over BLE between iPhone and custom earbuds. This works reliably on iPhone 14 / 15 / 16, but on iPhone 17 (Bluetooth 6, N1 chip) we see severe and repeatable BLE packet loss, affecting both microphone uplink and TTS downlink. Our audio stream 16 kHz, 16-bit mono PCM 20 ms frames (~640 bytes) continuous bidirectional BLE streaming What happens on iPhone 17 BLE packets are frequently dropped entire audio frames are missing results in ASR gaps and broken TTS playback occurs even with strong RSSI and no RF interference Same firmware, same BLE protocol, same MTU and connection interval work normally on older iPhones. Questions We would like to know: Did Bluetooth 6 / N1 change BLE throughput, buffering, or scheduling? Are there new limits on sustained notify / write-without-response traffic? Is BLE audio now arbitrated differently against Wi-Fi / A2DP on iPhone 17? Is BLE still expected to support low-latency continuous audio streaming on iPhone 17, or is this no longer a safe assumption? Any guidance or new best practices would be greatly appreciated. Best regards, Valenti Zhang
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watchOS 10.2 Bluetooth in the background often disconnects
My watch APP needs to keep Bluetooth connected with peripherals whether it is in the foreground or background, but the results of my test show that the connection in the background is very unstable, sometimes you can keep the Bluetooth on for a day, but sometimes it will be disconnected 50 times a day, and every time it is disconnected, I will immediately initiate a reconnection, it is certain that there is no problem with the peripheral Bluetooth, because I have another iOS device that has been stably connected to the peripheral, I want to know what causes this instability, and if there is any solution, if someone can provide relevant advice, I will be very grateful
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Dec ’25
iOS 26 Bluetooth repeatedly sends connection parameter updates
When my Bluetooth peripheral device has both HID and MIDI services, the iOS Bluetooth host repeatedly sends different "Control Opcode: LL_CONNECTION_UPDATE_IND" to the peripheral, updating approximately every 100ms. The Bluetooth peripheral cannot handle such high-frequency update requests and typically disconnects with an error 0x28. My Bluetooth device uses the NRF52832 chip, and I have communicated with NORDIC and replicated this issue. This problem only occurs on iOS 26; it does not happen on earlier versions. I think it might be caused by the HID service in iOS requesting faster connection parameters for low latency, which then gets erroneously reverted for an unknown reason, leading to repeated competition and entering into a deadlock. Here is the communication record with NORDIC: https://devzone.nordicsemi.com/f/nordic-q-a/124994/ios-26-bluetooth-disconnect-issues This is the screenshot captured using the Bluetooth sniffer:
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Nov ’25
BLE Notification & Write Latency/Batching on iOS (vs Android) – CoreBluetooth Real-Time Question
I am using a Raspberry Pi 5 (BLE 5.0) to read sensor data and send it via D-Bus and BlueZ to a Flutter application (flutter_blue_plus) for both iOS and Android. The goal is to display these real-time sensor updates directly on the device. On Android, the data transmission is immediate and the real-time visualization is extremely smooth and fast. However, on iOS, both BLE write and notification commands appear with noticeable latency—not only in real-time displays, but also when comparing ordinary notification feedback between the Raspberry Pi terminal and the iOS app. It seems that iOS buffers several BLE packets internally and then dispatches them in batches, which always introduces an additional delay. Additional setup details: I sample and transmit data every 25ms, sending binary packets of 20 bytes (length shouldn’t be a limiting factor). On the iOS side I am using an iPhone 15 Pro with iOS 18.6.2 (BLE 5.3). The Raspberry Pi (using btmon for logging) confirms after connection setup that the connection interval is fixed at 30ms (and cannot be changed). I have tried sending BLE packets every 30ms so that exactly one packet arrives per interval, but this made no difference—the latency and batch delivery remain. Interestingly, faster transmission rates (e.g. sending every 10ms) make the real-time display look smoother on iOS, but the guaranteed overall system latency does not improve. Also these methods used: write-without-response, using app in release modus (no debugging) Is there anyone familiar with this problem or a potential solution? Or is iOS simply not optimized for true real-time BLE data streaming and visualization? Any pointers, technical insights or workarounds would be greatly appreciated.
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Nov ’25
iOS26 background lock screen Blood glucose monitoring Bluetooth low energy disconnect sleep
First, our app communicates with our blood glucose monitor (CGM) using Bluetooth Low Energy (BLE). On an iPhone 14 Pro with iOS 26.0.1, Bluetooth communication works properly even when the app is in the background and locked. Even if the phone and CGM are disconnected, the app continues to scan in the background and reconnects when the phone and CGM are back in close proximity. It won't be dormant in the background or when the screen is locked. This effectively ensures that diabetic users can monitor their blood glucose levels in real time. However, after using iOS 26.0.1 on the iPhone 17, we've received user feedback about frequent disconnections in the background. Our logs indicate that Bluetooth communication is easily disconnected when switching to the background, and then easily dormant by the system, especially when the user's screen is locked. This situation significantly impacts users' blood glucose monitoring, and users are unacceptable. What can be done?
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Oct ’25
My user can't pair bluetooth peripheral, due to device lost in SYSTEM BLUETOOTH PREPHERAL LIST
[sysdiagnose_2025.10.01_18-29-27+0800_iPhone-OS_iPhone_23A341] I got sysdiagnose from my app user.He can't pair his bluetooth peripheral. in the sysdiagnose,I found this: device AC:7A:94:85:47:F4 is already paired, with a different irk (old:F5 C9 4F 5A 4E BE D0 20 0A 1F F7 DC 3A 89 E0 3A new 4A 8A 00 4C FF D0 CE 7B 61 13 FA B3 84 F4 65 29 ). Unpair first and then restart pairing. (status=65535) but there is no device in his iphone's SYSTEM BLUETOOTH PREPHERAL LIST. I don't know how to delete the irk info when you can't find it in SYSTEM BLUETOOTH PREPHERAL LIST. PLEASE answer me. THANKS.
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Oct ’25
AirPods with H2 and studio-quality recording - how to replicate Camera video capture
Using an iPhone Pro 12 running iOS 26.0.1, with AirPods Pro 3. Camera app does capture video with what seems to be "Studio Quality Recording". Am trying to replicate that SQR with my own Camera like app, and while I can pull audio in from the APP3 mic, and my video capture app is recording a 48,000Hz high-bitrate video, the audio still sounds non-SQR. I'm seeing bluetoothA2DP , bluetoothLE , bluetoothHFP as portType, and not sure if SQR depends on one of those? Is there sample code demonstrating a SQR capture? Nevermind video and camera, just audio even? Also, I don't understand what SQR is doing between the APP3 and the iPhone. What codec is that? What bitrate is that? If I capture video using Capture and inspect the audio stream I see mono 74.14 kbit/s MPEG-4 AAC, 48000 Hz. But I assume that's been recompressed and not really giving me any insight into the APP3 H2 transmission?
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Oct ’25
HID Braille keyboard support on iPhone 6S
Hello, I am working on a Braille keyboard by using HID approach. Current the device works with iPhone 11 and SE3. However, when tested in iPhone 6s with iOS 15, although the device can be connected and recognized as Braille device in VoiceOver screen, the phone shows no response to key press report. Would there be any requirement at points such as HID descriptor for iPhone 6s support on Braille device? If iPhone 6s does not support such devices, what is the minimum system requirements? Thank you!
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Sep ’25
How can I get a cover-art image via Bluetooth BIP
I want to get Cover-Art Image over Bluetooth. From the SDP Discover iPhoneSE, it support Cover-Art Feature. I connect and config OBEX Channel with L2CAP ERTM, it is successful. I send connect_request the OBEX Connect, the iPhone always no any response, and l2cap s-frame response from iPhone always failed. From the Apple Developer, it need Apple Authentication Chip. Is it still necessary now? Are there any other ways to obtain album pictures?
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Jun ’25
IOBluetoothHandsFreeDevice API confusion
I wonder how one would use IOBluetoothHandsFree APIs to interact from macOS app with a bluetooth device that implements bluetooth hands free profile. My current observation is as follows: IOBluetoothDevice object representing the device correctly identifies it as a hands free device, i.e.: there is a proper record in services array, that matches the kBluetoothSDPUUID16ServiceClassHandsFree uuid, the IOBluetoothDevice handsFreeDevice property returns 1 Attempt to create IOBluetoothHandsFreeDevice using IOBluetoothDevice as described above (i.e. [[IOBluetoothHandsFreeDevice alloc] initWithDevice: myIOBluetoothDeviceThatHasHandsFreeDevicePropertySetTo1 delegate: self]) results in the following output in debugger console: SRS-XB20 is not a hands free device but trying anyways. Subsequent call to connect on an object constructed as above results in the following stream of messages: API MISUSE: <CBClassicPeer: 0x1442447b0 6D801974-5457-9ECE-0A9B-8343EC4F60AA, SRS-XB20, connected, Paired, b8:d5:0b:03:62:70, devType: 19, PID: 0x1582, VID: 0x0039> Invalid RFCOMM CID -[IOBluetoothRFCOMMChannel setupRFCOMMChannelForDevice] No channel <IOBluetoothRFCOMMChannel: 0x600003e5de00 SRS-XB20, b8-d5-0b-03-62-70, CID: 0, UUID: 110F > AddInstanceForFactory: No factory registered for id <CFUUID 0x600000b5e3e0> F8BB1C28-BAE8-11D6-9C31-00039315CD46 -[IOBluetoothRFCOMMChannel setupRFCOMMChannelForDevice] No channel <IOBluetoothRFCOMMChannel: 0x600003e5de00 SRS-XB20, b8-d5-0b-03-62-70, CID: 0, UUID: 110F > API MISUSE: <CBClassicPeer: 0x1442447b0 6D801974-5457-9ECE-0A9B-8343EC4F60AA, SRS-XB20, connected, Paired, b8:d5:0b:03:62:70, devType: 19, PID: 0x1582, VID: 0x0039> Invalid RFCOMM CID Note that this device's handsFreeServiceRecord looks as follows: ServiceName: Hands-free unit RFCOMM ChannelID: 1 Attributes: { 0 = "uint32(65539)"; 256 = "string(Hands-free unit)"; 9 = "{ { uuid32(00 00 11 1e), uint32(262) } }"; 785 = "uint32(63)"; 1 = "uuid32(00 00 11 1e)"; 6 = "{ uint32(25966), uint32(106), uint32(256) }"; 4 = "{ { uuid32(00 00 01 00) }, { uuid32(00 00 00 03), uint32(1) } }"; } and explicit attempt to open RFCOMM channel no 1 ends like this: WARNING: Unknown error: 911 Failed to open RFCOMM channel -[IOBluetoothRFCOMMChannel setupRFCOMMChannelForDevice] No channel <IOBluetoothRFCOMMChannel: 0x6000002036c0 SRS-XB20, b8-d5-0b-03-62-70, CID: 1, UUID: 111E > AddInstanceForFactory: No factory registered for id <CFUUID 0x600003719260> F8BB1C28-BAE8-11D6-9C31-00039315CD46 -[IOBluetoothRFCOMMChannel waitforChanneOpen] CID:1 - timed out waiting to open -[IOBluetoothDevice openRFCOMMChannelSync:withChannelID:delegate:] CID:1 error -536870212 call returned: -536870212
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128
Jun ’25
`sdpQueryComplete:status:` not being called
I try to refresh the SDP data for a Bluetooth device that has reconnected. So when I receive connect notification I call -[IOBluetoothDevice performSDPQuery:] passing object, that should receive the query completion call. What I observe is that sdpQueryComplete:status: is not being called, buit calling performSDPQuery causes additional connect notification to be dispatched. Running this under debugger results in some weird log line: [IOBluetooth] **** This currently won't trigger SDP delegate I run this code on Sequoia 15.5
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May ’25
How can I prevent virtual location from affecting the security of my app
Hello, I have noticed that some users have modified their real location through an app called "MGU" to bypass my app's security checks. I want to know how to protect my app and detect users using virtual location. I have reproduced the process of virtual positioning here: Insert a plug-in through the interface at the bottom of the phone and connect it via Bluetooth on the phone Set the desired positioning target on the "MGU" app Turn off your phone's WiFi, network, and location for 10 seconds, then turn it back on At this point, virtual positioning is successful. Please assist me in troubleshooting this issue and inform me of the principle of implementing virtual positioning in this app and how to prevent it. The following is the screen recording of virtual positioning operation: https://flowus.cn/share/145b3232-26c3-4ea3-b3ff-4aad1495eb4d
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Apr ’25
NSLocalizedDescription = \"Peer removed pairing information\";
After hardware and mobile phone hid mode pairing, the first connection is successful, after a while disconnect and reconnect,APP monitoring Bluetooth error NSLocalizedDescription = "Peer removed pairing information"; Failed to connect Hardware engineers detect the pairing information and find that the local pairing information of the iPhone has changed, which is a non-mandatory phenomenon
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163
Apr ’25
BLE timeout issue when connecting two devices on iOS 18 (but not iOS 16)
Hi, We’re developing a BLE peripheral device and encountered a connection issue when connecting two devices (Device A and Device B) simultaneously to an iOS device. Problem: On iOS 18, we are experiencing occasional BLE timeouts and disconnections when both devices are connected at the same time. On iOS 16, we did not encounter this issue under the same conditions. What we’ve tried: Adjusted the connection interval from 30ms to 15ms. This seems to have improved stability somewhat. However, we still observe intermittent timeout/disconnection issues. Questions: Are there any known changes in BLE connection handling or timing constraints in iOS 18? Are there recommended connection parameter settings (interval, latency, timeout, etc.) for multi-device BLE connections in iOS? Is there a way to debug or log more details about the disconnection reasons on the iOS side? Any guidance or suggestions would be greatly appreciated.
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135
Apr ’25