The GPL is not compatible with Apple's App Store restrictions, so giving away your source code is not sufficient to comply with the GPL.
"The primary problem is that Apple imposes numerous legal restrictions on use and distribution...through the iTunes Store Terms of Service, which is forbidden by section 6 of GPLv2."
There is also a significant difference between giving away free applications and giving away the source code. Both from an internal perspective (the company may want to charge for the product or related products or products on other platforms now or in the future) and an external perspective (the app may require other software for which the company does not have rights to release source code).
"Here's a free loaf of bread."
"Why don't you just give me the bread factory and the farms that supplied the ingredients?"
"The primary problem is that Apple imposes numerous legal restrictions on use and distribution...through the iTunes Store Terms of Service, which is forbidden by section 6 of GPLv2."
https://www.fsf.org/news/2010-05-app-store-compliance
See also https://apple.stackexchange.com/a/59495
There is also a significant difference between giving away free applications and giving away the source code. Both from an internal perspective (the company may want to charge for the product or related products or products on other platforms now or in the future) and an external perspective (the app may require other software for which the company does not have rights to release source code).
"Here's a free loaf of bread."
"Why don't you just give me the bread factory and the farms that supplied the ingredients?"