To provide application updates in Windows, we can simply download the installer and run it. Applications are installed in %PROGRAMFILES% and shortcuts are placed in various places. Keys and values are added to the registry to provide an entry in the system's Programs list.
To provide application updates in Linux, we can use the system's package manager.
How do you provide application updates in Mac OS X? I think in general you simply drag .app bundles to /Applications? Does the system provide any sort of registry other than "look in /Applications folder"? Should the general flow of updating simply involve downloading an opening a DMG file, prompting the user to drag the new application bundle into /Applications? Will copying an app bundle to a folder delete the existing bundle before copying, or does it act like a normal folder (e.g. add and replace existing files)? I'd just like some general information on how I know go about implementing a 'check for updates' feature consistent with what's expected for a Mac OS X application.
It sounds like you should look into Sparkle.
In my experience as a Mac user (not a Cocoa dev), it's become the de facto standard for self-updating apps, save for a few monoliths like Microsoft Office and Adobe CS.
来源：https://stackoverflow.com/questions/3455021/application-updates-in-mac-os-x