Re: Best pattern to follow for scheduling an event
Re: Best pattern to follow for scheduling an event
- Subject: Re: Best pattern to follow for scheduling an event
- From: Michael Nickerson <email@hidden>
- Date: Thu, 8 Nov 2007 15:01:45 -0500
On Nov 8, 2007, at 1:05 PM, John Stiles wrote:
I have a method that needs to schedule a "cleanup pass" to occur in
the near future. The method might be called once, ten times, or a
hundred times in a row, but I only need to clean up one time. To
implement this, I used the following pattern, and I'm wondering if
it was the best way to go.
First, when the object is first created, I create a timer. I
scheduled its fire date to be in the distant, distant future:
m_deferredFixupTimer = [[NSTimer
scheduledTimerWithTimeInterval:DBL_MAX
target:myObject
selector:@selector(doFixUp:)
userInfo:NULL
repeats:YES] retain];
John, instead of using a timer you could just use a delayed perform.
You can cancel said perform when you get a new call before re-calling
it.
The code would be something like this:
- (void)cleanupMethod:(id)sender
{
//Your clean-up code here
}
- (void)doCleanup
{
[NSObject cancelPreviousPerformRequestsWithTarget:self
selector:@selector(cleanupMethod:) object:self];
[self performSelector:@selector(cleanupMethod:) withObject:self
afterDelay:0.25];
}
Of course, there's caveat's doing it this way: your cleanup method
will need to know what objects are actually being cleaned up, as it's
not passed that info. Doing it this way, though, your cleanup method
would only be called once, and would only get called when objects
actually need to be cleaned up.
I'm not entirely certain how you have your code setup, so I don't know
if this would be the best method to use. But if you have some sort of
central object that does cleanup of other objects, this would be a
good alternative.
I use this with sliders that are updating something in the GUI mostly,
so that it's not updating every single time the slider's value
changes. You can, of course, adjust the delay to whatever works best
for you, and if you want it to run in run loop modes other than
NSDefaultRunLoopMode you can add in the inModes: option to the
performSelector:... method and pass it an array of run loop modes
you'd like it to run in.
--------------------------------------
Darkshadow
(aka Michael Nickerson)
http://www.nightproductions.net
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