IOServiceNameMatching can't consistently find dext service

Question

I'm using the following code to find the dext service. The code is executed on start-up. This is an app we develop for iPads and the driver is enabled in iOS settings before launching the app.

    io_service_t mService = IO_OBJECT_NULL;
    kern_return_t ret = kIOReturnSuccess;
    io_iterator_t iterator = IO_OBJECT_NULL;

    //temporary checking for all services
    //I refined it further using other keys
    CFMutableDictionaryRef matchingDict = IOServiceMatching("IOUserService");
    
    if (__builtin_available(iOS 15.0, *)) {
        ret = IOServiceGetMatchingServices(kIOMainPortDefault, matchingDict, &iterator);
    } else {
        // Fallback on earlier versions
    }
    if (ret != kIOReturnSuccess)
    {
        printf("Unable to find service");
    }
    
    while ((mService = IOIteratorNext(iterator)) != IO_OBJECT_NULL)
    {
        //Only able to find "MyDriver" if launching the app first and then connecting the device
        ret = IOServiceOpen(mService, mach_task_self_, 0, &mConnection);
        ..........
    }

We have no problem matching on the device using IOServiceMatching("IOUSBDevice") and idVendor + idProduct as keys. It doesn’t matter if the device is connected before or after launching the app, matching on the device always returns the correct value.

The problem I'm facing is finding the matching driver.

1. When the USB device is connected before launching the app (with driver already enabled in iOS Settings), I notice MyDriver Start() doesn't get called, which results in MyDriver not showing up when I try to get matching service with IOServiceMatching("IOUserService"). Others such as AppleBCMWLANBusInterfacePCIe, IO80211ReporterProxy, AppleBCMWLANCore are available but MyDriver.

I tried using match notifications but got the same result as IOServiceGetMatchingServices.

2. If I launch the app first and then connect my USB device, MyDriver Start() is called and MyDriver is available. This allows me to find the driver and call IOServiceOpen on it. Everything then works as expected.

3. With the driver up and running, if I disabled and reenabled the driver in iOS settings without disconnecting/reconnecting the device, MyDriver Start() wouldn't get called, and get matching service with IOServiceMatching("IOUserService") wouldn't find it again.

In the driver info.plist file we use IOUSBHostDevice for IOProviderClass since our device is a non-HID USB device. From what I’m seeing, looks like the device would need to be physically connected after launching the app for the driver to start and the matching to happen properly. I’m wondering if anything can be done to get it to work for the workflows I mentioned in #1 and #3 above.

Thanks

MyDriver Info.plist file

<plist version="1.0">
<dict>
    <key>IOKitPersonalities</key>
    <dict>
        <key>MyDriver</key>
        <dict>
            <key>CFBundleIdentifier</key>
            <string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
            <key>CFBundleIdentifierKernel</key>
            <string>com.apple.kpi.iokit</string>
            <key>CFBundleName</key>
            <string>$(PRODUCT_NAME)</string>
            <key>IOClass</key>
            <string>IOUserService</string>
            <key>IOMatchCategory</key>
            <string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
            <key>IOProviderClass</key>
            <string>IOUserResources</string>
            <key>IOResourceMatch</key>
            <string>IOKit</string>
            <key>IOUserClass</key>
            <string>MyDriver</string>
            <key>IOUserServerName</key>
            <string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
            <key>MyDriverUserClientProperties</key>
            <dict>
                <key>IOClass</key>
                <string>IOUserUserClient</string>
                <key>IOUserClass</key>
                <string>MyDriverClient</string>
            </dict>
            <key>bConfigurationValue</key>
            <integer>1</integer>
            <key>bInterfaceNumber</key>
            <integer>0</integer>
            <key>idProduct</key>
            <integer>1234</integer>
            <key>idVendor</key>
            <integer>5678</integer>
        </dict>
    </dict>
</dict>
</plist>

MyDriver.entitlements

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>com.apple.developer.driverkit</key>
    <true/>
    <key>com.apple.developer.driverkit.transport.usb</key>
    <array>
        <dict/>
    </array>
    <key>com.apple.security.app-sandbox</key>
    <true/>
</dict>
</plist>