NSTimer

Inherits From:
NSObject

Conforms To:
NSObject (NSObject)

Declared In:
Foundation/NSTimer.h

Class Description

Timers work in conjunction with NSRunLoop objects. NSRunLoops control loops that wait for input, and they use timers to help determine the maximum amount of time they should wait. When the timer's time limit has elapsed, the NSRunLoop fires the timer (causing its message to be sent), then checks for new input.

There are several ways to create a timer. The scheduledTimerWithTimeInterval... class methods automatically register the new timer with the current NSRunLoop object in the default mode (NSDefaultRunLoopMode). The timerWithTimeInterval... class methods create timers that you may register at a later time by sending the message addTimer:forMode: to the NSRunLoop. If you specify that the timer should repeat, it will automatically reschedule itself after it fires.

There is no method that removes the association of a timer from an NSRunLoop-send the timer the invalidate message instead. invalidate disables the timer, so it will no longer affect the NSRunLoop.

See the NSRunLoop class description for more information on NSRunLoops.

Creating a timer

+ scheduledTimerWithTimeInterval:
invocation:repeats:

+ scheduledTimerWithTimeInterval:target:selector:
userInfo:repeats:

+ timerWithTimeInterval:invocation:repeats:

+ timerWithTimeInterval:target:selector:
userInfo:repeats:

Firing a timer

- fire

Stopping a timer

- invalidate

Getting information about a timer

- isValid

- fireDate

- timeInterval

- userInfo

Class Methods

scheduledTimerWithTimeInterval:invocation:repeats:

Returns a new NSTimer object and registers it with the current NSRunLoop in the default mode. After seconds have elapsed, the timer fires, sending invocation's message to its target. If seconds is less than or equal to 0.0, this method chooses a nonnegative interval. If repeats is YES, the timer will repeatedly reschedule itself.

scheduledTimerWithTimeInterval:target:selector:userInfo:repeats:

Returns a new NSTimer object and registers it with the current NSRunLoop in the default mode. After seconds have elapsed, the timer fires, sending the message aSelector to target. The aSelector method must take only one argument, an NSTimer object. The timer passes itself as the argument to aSelector. To pass more information to the target, use userInfo. The target gets userInfo by sending userInfo to the timer.

If seconds is less than or equal to 0.0, this method chooses a nonnegative interval. If repeats is YES, the timer will repeatedly reschedule itself.

timerWithTimeInterval:invocation:repeats:

Returns a new NSTimer that, when registered, will fire after seconds. If seconds is less than or equal to 0.0, this method chooses a nonnegative interval. Upon firing, the timer sends invocation's message to its target. If repeats is YES, the timer will repeatedly reschedule itself after firing.

timerWithTimeInterval:target:selector:userInfo:repeats:

Returns a new NSTimer that, when registered, will fire after seconds. Upon firing, the timer sends aSelector to target. The aSelector method must take only one argument, an NSTimer object. The timer passes itself as the argument to aSelector. To pass more information to the target, use userInfo. The target gets userInfo by sending userInfo to the timer.

If seconds is less than or equal to 0.0, this method chooses a nonnegative interval. If repeats is YES, the timer will repeatedly reschedule itself.

Instance Methods

fire

Causes the receiver's message to be sent to its target.

fireDate

Returns the date at which the receiver will fire. If the timer is no longer valid, this method returns the last date at which the timer fired. Use isValid to verify that the timer is valid.

See also: - isValid

invalidate

Stops the receiver from ever firing again. This is the only way to remove a timer from an NSRunLoop.

isValid

Returns YES if the timer is currently valid, no otherwise.

timeInterval

Returns the time interval associated with the receiver.

userInfo

Additional data the target may use when the receiver is fired.

See also: + scheduledTimerWithTimeInterval:target:selector:userInfo:repeats:, + timerWithTimeInterval:target:selector:userInfo:repeats:

Copyright © 1997, Apple Computer, Inc. All rights reserved.