iphone - Is there inter-app communication when apps start in iOS? -

iphone - Is there inter-app communication when apps start in iOS? -

i relatively new ios app development , i'm trying figure out things that, me, more abstract. how apps know when other apps start? closest illustration can think of i'm trying inquire when music playing in background , open app has sound , music stops. new app taking authorization or there inter app communication? if there communication how communication work? message accessed or what?

sorry if didn't create much sense, tried elaborate best could. couldn't find on over apple's developer website. in advance!

there no inter-app communication. each app living in own world, , far app concerned, it's app on phone. way communication happens app talks system, , scheme talks app. way scheme sends messages app in delegate of framework you're working with. in example, opening app play sound send message system, , scheme tell other app stop sound playback. other app has no thought app initiated stop. illustration appdelegate. app delegate send app messages such application:didfinishlaunchingwithoptions:, in method custom initialization of app or applicationwillresignactive: sent when user presses home button or receives phone call, here might want save game, etc.

in fact ios scheme quite complicated, much complicated explained in detail here highly suggest reading apple developer documentation, of can little dry, best coherent absolute beginners.

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