function get_device_type()
{
 //全部变成小写字母
 $agent = strtolower($_SERVER['HTTP_USER_AGENT']);
 $type = 'other';
 //分别进行判断
 if(strpos($agent, 'iphone') || strpos($agent, 'ipad'))
{
 $type = 'ios';
 } 
 
 if(strpos($agent, 'android'))
{
 $type = 'android';
 }
 return $type;
}

<?php
if(strpos($_SERVER['HTTP_USER_AGENT'], 'iPhone')||strpos($_SERVER['HTTP_USER_AGENT'], 'iPad')){
 echo 'systerm is IOS';
}else if(strpos($_SERVER['HTTP_USER_AGENT'], 'Android')){
 echo 'systerm is Android';
}else{
 echo 'systerm is other';
}
?>

function get_device_type()
{
 //全部变成小写字母
 $agent = strtolower($_SERVER['HTTP_USER_AGENT']);
 $type ='other';
 //分别进行判断
 if(strpos($agent,'iphone') || strpos($agent,'ipad'))
{
 $type ='ios';
 }
 
 if(strpos($agent,'android'))
{
 $type ='android';
 }
 return$type;
}

$user_agent = $_SERVER['HTTP_USER_AGENT']; 
if (strpos($user_agent, 'MicroMessenger') === false) { 
 // 非微信浏览器禁止浏览 
 echo "HTTP/1.1 401 Unauthorized"; 
} else { 
 // 微信浏览器，允许访问 
 echo "MicroMessenger"; 
 // 获取版本号 
 preg_match('/.*?(MicroMessenger\/([0-9.]+))\s*/', $user_agent, $matches); 
 echo '<br>Version:'.$matches[2]; 
}