NSProcessInfo Class Reference

Inherits from
NSObject
Conforms to
NSObject (NSObject)
Framework
/System/Library/Frameworks/Foundation.framework
Availability
Available in iOS 2.0 and later.
Companion guide
Interacting with the Operating System
Declared in
NSProcessInfo.h
Related sample code

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

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 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 AppKit 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 AppKit 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.

Tasks

Getting the Process Information Agent

Accessing Process Information

Getting Host Information

Getting Computer Information

Class Methods

processInfo

Returns the process information agent for the process.

+ (NSProcessInfo *)processInfo
Return Value

Shared process information agent for the process.

Discussion

An NSProcessInfo object is created the first time this method is invoked, and that same object is returned on each subsequent invocation.

Availability
  • Available in iOS 2.0 and later.
Related Sample Code
Declared In
NSProcessInfo.h

Instance Methods

activeProcessorCount

Provides the number of active processing cores available on the computer.

- (NSUInteger)activeProcessorCount
Return Value

Number of active processing cores.

Availability
  • Available in iOS 2.0 and later.
See Also
Declared In
NSProcessInfo.h

arguments

Returns the command-line arguments for the process.

- (NSArray *)arguments
Return Value

Array of strings with the process’s command-line arguments.

Availability
  • Available in iOS 2.0 and later.
Declared In
NSProcessInfo.h

environment

Returns the variable names and their values in the environment from which the process was launched.

- (NSDictionary *)environment
Return Value

Dictionary of environment-variable names (keys) and their values.

Availability
  • Available in iOS 2.0 and later.
Declared In
NSProcessInfo.h

globallyUniqueString

Returns a global unique identifier for the process.

- (NSString *)globallyUniqueString
Return Value

Global ID for the process. The ID includes the host name, process ID, and a time stamp, which ensures that the ID is unique for the network.

Discussion

This method generates a new string each time it is invoked, so it also uses a counter to guarantee that strings created from the same process are unique.

Availability
  • Available in iOS 2.0 and later.
See Also
Declared In
NSProcessInfo.h

hostName

Returns the name of the host computer.

- (NSString *)hostName
Return Value

Host name of the computer.

Availability
  • Available in iOS 2.0 and later.
Declared In
NSProcessInfo.h

operatingSystem

Returns a constant to indicate the operating system on which the process is executing.

- (NSUInteger)operatingSystem
Return Value

Operating system identifier. See “Constants” for a list of possible values. In OS X, it’s NSMACHOperatingSystem.

Availability
  • Available in iOS 2.0 and later.
Declared In
NSProcessInfo.h

operatingSystemName

Returns a string containing the name of the operating system on which the process is executing.

- (NSString *)operatingSystemName
Return Value

Operating system name. In OS X, it’s @"NSMACHOperatingSystem"

Availability
  • Available in iOS 2.0 and later.
Declared In
NSProcessInfo.h

operatingSystemVersionString

Returns a string containing the version of the operating system on which the process is executing.

- (NSString *)operatingSystemVersionString
Return Value

Operating system version. This string is human readable, localized, and is appropriate for displaying to the user. This string is not appropriate for parsing.

Availability
  • Available in iOS 2.0 and later.
Declared In
NSProcessInfo.h

physicalMemory

Provides the amount of physical memory on the computer.

- (unsigned long long)physicalMemory
Return Value

Amount of physical memory in bytes.

Availability
  • Available in iOS 2.0 and later.
Declared In
NSProcessInfo.h

processIdentifier

Returns the identifier of the process.

- (int)processIdentifier
Return Value

Process ID of the process.

Availability
  • Available in iOS 2.0 and later.
See Also
Related Sample Code
Declared In
NSProcessInfo.h

processName

Returns the name of the process.

- (NSString *)processName
Return Value

Name of the process.

Discussion

The process name is used to register application defaults and is used in error messages. It does not uniquely identify the process.

Availability
  • Available in iOS 2.0 and later.
See Also
Related Sample Code
Declared In
NSProcessInfo.h

processorCount

Provides the number of processing cores available on the computer.

- (NSUInteger)processorCount
Return Value

Number of processing cores.

Availability
  • Available in iOS 2.0 and later.
See Also
Declared In
NSProcessInfo.h

setProcessName:

Sets the name of the process.

- (void)setProcessName:(NSString *)name
Parameters
name

New name for the process.

Discussion

Availability
  • Available in iOS 2.0 and later.
See Also
Declared In
NSProcessInfo.h

systemUptime

Returns how long it has been since the computer has been restarted.

- (NSTimeInterval)systemUptime
Return Value

An NSTimeInterval indicating how long since the computer has been restarted.

Availability
  • Available in iOS 4.0 and later.
Declared In
NSProcessInfo.h

Constants

NSProcessInfo—Operating Systems

The following constants are provided by the NSProcessInfo class as return values for operatingSystem.

enum {
   NSWindowsNTOperatingSystem = 1,
   NSWindows95OperatingSystem,
   NSSolarisOperatingSystem,
   NSHPUXOperatingSystem,
   NSMACHOperatingSystem,
   NSSunOSOperatingSystem,
   NSOSF1OperatingSystem
};
Constants
NSHPUXOperatingSystem

Indicates the HP UX operating system.

Available in iOS 2.0 and later.

Declared in NSProcessInfo.h.

NSMACHOperatingSystem

Indicates the OS X operating system.

Available in iOS 2.0 and later.

Declared in NSProcessInfo.h.

NSOSF1OperatingSystem

Indicates the OSF/1 operating system.

Available in iOS 2.0 and later.

Declared in NSProcessInfo.h.

NSSolarisOperatingSystem

Indicates the Solaris operating system.

Available in iOS 2.0 and later.

Declared in NSProcessInfo.h.

NSSunOSOperatingSystem

Indicates the Sun OS operating system.

Available in iOS 2.0 and later.

Declared in NSProcessInfo.h.

NSWindows95OperatingSystem

Indicates the Windows 95 operating system.

Available in iOS 2.0 and later.

Declared in NSProcessInfo.h.

NSWindowsNTOperatingSystem

Indicates the Windows NT operating system.

Available in iOS 2.0 and later.

Declared in NSProcessInfo.h.



© 2012 Apple Inc. All Rights Reserved. (Last updated: 2012-05-14)

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