DFU bootloader with Qt - problem for iOS

Question

Hello everyone, 
 
 I am working on DFU bootloader application for android and iOS (using Qt C++). 
 For android everything works fine, but for iOS I have problems. 
 In order to enter DFU mode I need to send 0x0104 to control point dfu characteristic and after this device is reset in DFU mode. 
 After this my app doing next steps: connect to device again > discover services (there is only DFU service now) > write descriptor for CP characteristic (to enable notifications) > THERE IS A PROBLEM - The delegate for CBPeripheral does not implement -[peripheral:didModifyServices:]. 
 I tried to increment MAC address (device uuid) when enter in DFU mode because I read that devices may be cached by the phone and if they change services list while connected that could cause the problem, but the problem is still there. 
 Has anyone had a similar problem/experience? 
 
 Thanks in advance.

Mostafa Berg · Answer

If you want to implement peripheral did modify services then you need to have the service changed enabled (but no need to indicate when services change as iOS will automatically disable caching for this peripheral when it finds the service there). However, our implementation depends on the peripheral disconnecting and starting again in bootloader, with MAC address + 1. 
 Only then you can reconnect, discover your services, enable notifications and start the flashing process. 
 I would suggest that you follow the same steps as the nR/F Connect app as this is the supported way to flash OTA :) 
 Note 1: , if you add service change to your peripheral's FW, iOS will not see that because it has already cached the GATT table, so you'll have to put the phone in airplane mode or disable bluetooth from the settings (not control center) for at least 10 seconds to clear the cache. if that doesn't work you should try again, or try to restart the phone. after the new GATT table is fetched and service change is there, iOS will no longer cache this peripheral. 
 
 Note 2: iOS has no access to the peripheral's MAC address, so you can't rely on MAC address + 1 to identity the node, you should just scan for peripherals broadcasting DFU / Secure DFU services. additionally we have implemented a name set feature that allows you to set the broadcasting name of the peripheral upon restart so you can easily identify it, please use one of our DFU libraries for android or iOS to see how that works. Here is how iOS the iOS Library implements it . Note 3: Android allows you to get the peripheral's MAC address, so you won't need to scan like you do on iOS, you simply send the jump to bootloader command, then increment the mac address by one, and connect to that peripheral straight away. 
 let us know if you have any more issues so we can help out.

DFU bootloader with Qt - problem for iOS

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