Writing a privileged helper tool with SMJobBless()

Question

Even though the API has been open since Mac OS X Leopard, there\'s surprisingly, and unfortunately, very little documentation on how to correctly use SMJobBless()

Answer 1

In fact @KurtRevis's comment is right, you can use XPC APIs without using XPC services, and it is ideally suited to the job since.

Nathan de Vries has an excellent writeup of using XPC APIs with SMJobBless and has even modified the SMJobBless sample app to use mach XPC to both activate the job and for bidirectional communications:

http://atnan.com/blog/2012/02/29/modern-privileged-helper-tools-using-smjobbless-plus-xpc/

https://github.com/atnan/SMJobBlessXPC

Somewhat related to all this is avoiding unnecessary admin password prompts. See the following email list thread for ideas on how to check if the bundle version and code signature of an already installed helper match (which also allows you to remove a higher versioned helper in the case of a user downgrading):

http://www.cocoabuilder.com/archive/cocoa/309298-question-about-smjobbless.html

If you don't want to wade through the thread, here is a link to the modified SMJobBless sample project provided by Eric Gorr:

http://ericgorr.net/cocoadev/SMJobBless.zip

Also note that the ssd example mentioned in other answers here is still available online from Apple as part of the WWDC 2010 download bundle:

http://connect.apple.com/cgi-bin/WebObjects/MemberSite.woa/wa/getSoftware?code=y&source=x&bundleID=20645