The following works for me as well:

if (isset($_SERVER['HTTP_X_REQUESTED_WITH']) && $_SERVER['HTTP_X_REQUESTED_WITH'] == "com.systechdigital.bgmea") { 
    // web view Android
} else if ( (strpos($_SERVER['HTTP_USER_AGENT'], 'Mobile/') !== false) && (strpos($_SERVER['HTTP_USER_AGENT'], 'Safari/') == false) ) {
    // web view iOS
}
else {
    // responsive mobile view or others (e.g. desktop)
}

The following works for me as well: (in case you get puzzled and undefined index for $_SERVER['HTTP_X_REQUESTED_WITH'])

if (isset($_SERVER['HTTP_X_REQUESTED_WITH']) && $_SERVER['HTTP_X_REQUESTED_WITH'] == "com.systechdigital.bgmea") { 
    // web view Android
} else if ( (strpos($_SERVER['HTTP_USER_AGENT'], 'Mobile/') !== false) && (strpos($_SERVER['HTTP_USER_AGENT'], 'Safari/') == false) ) {
    // web view iOS
}
else {
    // responsive mobile view or others (e.g. desktop)
}