Is there a public Apple API which allows you to remove an application's dock icon at runtime? I have tried substituting an empty view with zero size via NSApplication's dockTile, but that simply erases the dock icon without reclaiming its space and launch indicator. I also know about the LSUIElement parameter in an application's info.plist, but this value is only evaluated on launch. It is not a runtime parameter.
It's a one way street: You can set your app to NSUIElement to hide the dock icon, then call [NSApp setActivationPolicy:NSApplicationActivationPolicyRegular]; to show it in the dock, but once it's there you can't remove it. So you could make the dock icon user-configurable, but you'd have to relaunch the app to hide the icon.
EDIT
You can call
setActivationPolicy:NSApplicationActivationPolicyProhibitedto hide dock-icon again – user1592530 Sep 18 '12 at 14:21
The comment is right. Works two ways nowadays – Daij-Djan Dec 24 '12 at 11:46
来源：https://stackoverflow.com/questions/8317101/add-remove-application-icon-from-dock-at-runtime