NSProcessInfo Class Reference

Overview

The NSProcessInfo class provides methods to access information about the current process. Each process has a single, shared NSProcessInfo object, known as process information agent.

The process information agent can return such information as the arguments, environment variables, host name, or process name. The processInfo class method returns the shared agent for the current process—that is, the process whose object sent the message. For example, the following line returns the NSProcessInfo object, which then provides the name of the current process:

NSString *processName = [[NSProcessInfo processInfo] processName];

The NSProcessInfo class also includes the operatingSystem method, which returns an enum constant identifying the operating system on which the process is executing.

NSProcessInfo objects attempt to interpret environment variables and command-line arguments in the user's default C string encoding if they cannot be converted to Unicode as UTF-8 strings. If neither conversion works, these values are ignored by the NSProcessInfo object.

Sudden Termination

Mac OS X v10.6 includes a new mechanism that allows the system to log out or shut down more quickly by, whenever possible, killing applications instead of requesting that they quit themselves.

Your application can enable this capability on a global basis and then manually override its availability during actions that could cause data corruption or a poor user experience by allowing sudden termination. Alternately, your application can just manually enable and disable this functionality.

The methods enableSuddenTermination and disableSuddenTermination decrement or increment, respectively, a counter whose value is 1 when the process is first created. When the counter's value is 0 the application is considered to be safely killable and may be killed by the system without any notification or event being sent to the process first.

Your application can support sudden termination upon launch by adding a key to the application’s Info.plist. If the NSSupportsSuddenTermination key exists in the Info.plist and has a value of YES, it is the equivalent of calling enableSuddenTermination during your application launch. This renders the application process killable right away. You can still override this behavior by invoking disableSuddenTermination.

Typically, you will disable sudden termination whenever your application defers work that must be done before the application terminates. If, for example, your application defers writing data to disk, and sudden termination is enabled, you should bracket the sensitive operations with a call to disableSuddenTermination, perform the necessary operations, and then send a balancing enableSuddenTermination message.

In agents or daemon executables that don't depend on Application Kit you can manually invoke enableSuddenTermination right away. You can then use the enable and disable methods whenever the process has work it must do before it terminates.

Some Application Kit functionality automatically disables sudden termination on a temporary basis to ensure data integrity.

• NSUserDefaults temporarily disables sudden termination to prevent process killing between the time at which a default has been set and the time at which the preferences file including that default has been written to disk.

• NSDocument temporarily disables sudden termination to prevent process killing between the time at which the user has made a change to a document and the time at which the user's change has been written to disk.

print (long)[[NSClassFromString(@"NSProcessInfo") processInfo] _suddenTerminationDisablingCount