I have a URLHandler that launches some application, the main code is as follows.
@implementation URLHandlerCommand
- (id)performDefaultImplementation {
You don't have to launch open using NSTask... open just calls into Launch Services, some of whose functionality is directly available from NSWorkspace.
To quit, you just call [[NSApplication sharedApplication] terminate:nil]. See NSApplication documentation.
This has been answered here: Proper way to exit iPhone application? however you should also take a look at August's answer. Although it's not the accepted answer, it has been voted higher and it also follows Apple's set standards since Apple advises against force quitting iPhone applications.