What APIs does iOS call when we download an app or update from AppSTore

I am curious to understand the pipeline iOS uses when I download an App from the Store. I know packages are in .ipa based. Does iOs simply download and explode the ipa onto dis开发者_StackOverflow社区k?

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The iOS installer does not inform your app about installation or an update. As far as your app is concerned, nothing happens when the user installs or updates the app. It is up to you to detect any changes the first/next time your app is launched.

If your app is suspended in the background while the user chooses to update it, the OS will kill your app without notifying you (just as it can be killed in other situations, such as low memory).

If your app is executing some task in the background while the user chooses to update it (e. g. playing music, doing VoIP, or finishing a background task), I don't know what happens, but I suspect the OS will terminate your app, giving it a chance to save state via the standard APIs you already use.