Xojo Conferences
XDCMay2019MiamiUSA

Platforms to show: All Mac Windows Linux Cross-Platform

NSTimerMBS class

Type Topic Plugin Version macOS Windows Linux Console & Web iOS
class Cocoa MBS MacCocoa Plugin 10.0 Yes No No Yes, macOS only No
Function: The cocoa timer class.
Example:
dim n as new NSTimerMBS(5, true)
Notes:
You use the NSTimer class to create timer objects or, more simply, timers. A timer waits until a certain time interval has elapsed and then fires, calling the action event. For example, you could create an NSTimer object that calls the action event, telling it to update itself after a certain time interval.

A timer is not a real-time mechanism; it fires only when one of the run loop modes to which the timer has been added is running and able to check if the timer's firing time has passed. Because of the various input sources a typical run loop manages, the effective resolution of the time interval for a timer is limited to on the order of 50-100 milliseconds. If a timer's firing time occurs during a long callout or while the run loop is in a mode that is not monitoring the timer, the timer does not fire until the next time the run loop checks the timer. Therefore, the actual time at which the timer fires potentially can be a significant period of time after the scheduled firing time.

Repeating Versus Non-Repeating Timers
You specify whether a timer is repeating or non-repeating at creation time. A non-repeating timer fires once and then invalidates itself automatically, thereby preventing the timer from firing again. By contrast, a repeating timer fires and then reschedules itself on the same run loop.

A repeating timer always schedules itself based on the scheduled firing time, as opposed to the actual firing time. For example, if a timer is scheduled to fire at a particular time and every 5 seconds after that, the scheduled firing time will always fall on the original 5 second time intervals, even if the actual firing time gets delayed. If the firing time is delayed so far that it passes one or more of the scheduled firing times, the timer is fired only once for that time period; the timer is then rescheduled, after firing, for the next scheduled firing time in the future.

Scheduling Timers in Run Loops
A timer object can be registered in only one run loop at a time, although it can be added to multiple run loop modes within that run loop. There are three ways to create a timer:

Use the Constructor to create the timer and schedule it on the current run loop in the default mode.

Once scheduled, the timer fires at the specified interval until it is invalidated. A non-repeating timer invalidates itself immediately after it fires. However, for a repeating timer, you must invalidate the timer object yourself by calling its invalidate method. Calling this method requests the removal of the timer from the current run loop; as a result, you should always call the invalidate method from the same thread on which the timer was installed. Invalidating the timer immediately disables it so that it no longer affects the run loop. The run loop then removes and releases the timer, either just before the invalidate method returns or at some later point. Once invalidated, timer objects cannot be reused.

Feedback, Comments & Corrections

This class has no sub classes.

Some examples which use this class:


The items on this page are in the following plugins: MBS MacCocoa Plugin.


NSTextViewMBS   -   NSTimeZoneMBS




Links
MBS FileMaker blog