Why install an application on VKontakte?

Question

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When developing an application for VK, you can make its installation mandatory. What does it give? In addition to the fact that on the application page instead of the "run" button, will there be an "install" button?

Answer 1

VK will ask for some permissions on startup. If you do not give access to them, then it will not be spared.

Answer 2

Elementary, Watson, print the $result array and you will see that not all values ​​in it are arrays, but there are also strings.
replace
with

if (!is_array($creative) || !array_key_exists('description', $creative)) {

Answer 3

Instead $creativewrite$creatives