Json结果转换为PHP变量

$jsonString = '{"name":"John", "age":30, "city":"New York"}';
$phpVariable = json_decode($jsonString);

$name = $phpVariable->name;
$age = $phpVariable->age;
$city = $phpVariable->city;

$name = $phpVariable['name'];
$age = $phpVariable['age'];
$city = $phpVariable['city'];

$jsonString = '{"name":"John", "age":30, "address":{"city":"New York", "country":"USA"}}';
$phpVariable = json_decode($jsonString);

$address = $phpVariable->address;
$city = $address->city;
$country = $address->country;

$jsonString = '{"name":"John", "age":30, "address":{"city":"New York", "country":"USA"}}';
$phpVariable = json_decode($jsonString, true);

$address = $phpVariable['address'];
$city = $address['city'];
$country = $address['country'];