Hi guys,
How would I be able to use timers? For example I want to show a certain text for 10 seconds and then I want to show a different text for the rest of the duration.
Thanks,
Kevin
+5
A:
The easiest way to defer an action is to use NSObject's performSelector:withObject:afterDelay:
- (void)performSelector:(SEL)aSelector withObject:(id)anArgument afterDelay:(NSTimeInterval)delay
Set your text the first time (or at init time) and then do something like:
[self performSelector:@selector(changeText) withObject:nil afterDelay:10.0];
You can cancel the request with:
+ (void)cancelPreviousPerformRequestsWithTarget:(id)aTarget selector:(SEL)aSelector object:(id)anArgument
which you will need to do if you want your object to be deallocated as performSelector retains both your object and the withObject parameter.
Peter N Lewis
2009-08-21 08:11:48
You have to do cancelPreviousPerformRequestWithTarget... ? I never have..
Mk12
2009-08-21 15:18:58
The docs say that performSelector:withObject:afterDelay: retains the receiver and the withObject. So your object will not be deallocated until that selector is performed.
Peter N Lewis
2009-08-22 06:08:37
+1 for posting code instead of saying RTFM.
willc2
2009-08-24 22:56:13
But you don't have to cancel if the selector does get performed right?
Mk12
2009-08-27 17:38:18
Correct. Essentially, the system retains both the receiver (self in this case) and the withObject, waits around 10 seconds, then invokes the method and releases the receiver and withObject. A consequence is that neither the receiver nor the withObject can be deallocated in the mean time.
Peter N Lewis
2009-08-28 01:28:44