Notification data occasionally corrupted on iOS 16.5

[jihen-ben-said]

In my Cordova application for iOS, I have encountered a peculiar issue. The application works flawlessly on devices such as the iPhone Xs running iOS 16.5. However, when testing it on the iPhone 13 with iOS 16.5, I noticed a problem. After initiating the startNotification process, the data received appears to be corrupted.

[peitschie]

Hi @jihen-ben-said

That certainly sounds surprising!

Are you able to share a good and bad notification example, just to see what kind of corruption you're dealing with? Is it a partial packet? Is it random bytes? Too long? Too short? Reversed?

Apple is usually pretty good about keeping their iOS behaviour consistent between hardware phones, but I have seen the occasional bug slip through.

[jihen-ben-said]

Hi,
In the following screenshots, one contains successfully received data, and the other contains yellow, indicating that a brace is missing, so invalid data. This is a random problem, as sometimes other characters such as "a/z/f",}..." or a number are missing.

[peitschie]

@jihen-ben-said do you have any control over the peripheral here? Do you know if this is using a Bluetooth notification or an indication?

The reason this matters, is because notifications are not guaranteed delivery and allowed to be dropped or omitted by the BLE protocol (e.g., like a UDP packet). You could possibly check this by using nrf Connect to connect to device, and look whether the INDICATE flag is set for this characteristic, or just the NOTIFY flag.

This could explain why the data goes missing, and only goes missing sometimes.

[jihen-ben-said]

Hi,
the notify characteristic have indicate true but the writing characteristic have indicate false