Managing Timers Passed as Variables - ios

Question

I am trying to perform what I thought was a simple task. I have a handful of repeating timers that need to be started and stopped.
I created methods for starting and stopping the timers, and attempt to pass the timers to the methods as parameters.
The problem is that the timers never seem to be stopped. Any ideas why this might not be working properly? Thank you!
Top of File:
#import "ViewController.h"
NSTimer *launchTimer;
NSTimer *transactionTimer;
Starting Method:
-(void) startingMethod {
NSString *urlString = #"http://google.com";
[[AsynchRequestService sharedInstance]
performAsynchronousURLRequest:urlString completion:^(BOOL success,
NSString *responseBody, NSString *responseStatus) {
if (success) {
[self stopResponseTimer:launchTimer];
}
else {
[self startResponseTimer:launchTimer
method:#selector(startingMethod)
interval:10];
}
}];
}
Method to Start the Timer:
-(void)startResponseTimer:(NSTimer *) timer method:(SEL) method
interval:(int) interval {
[timer invalidate];
timer = nil;
timer = [NSTimer scheduledTimerWithTimeInterval:interval target:self
selector:method userInfo:nil repeats:YES];
}
Method to Stop the Timer:
-(void)stopResponseTimer:(NSTimer *) timer {
NSLog(#"STOP TIMER");
[timer invalidate];
timer = nil;
}

Answer 1

Make startResponseTimer and `stopResponseTimer' take the pointer to the object pointer intead.
-(void)startResponseTimer:(NSTimer **) timer method:(SEL) method
interval:(int) interval {
[*timer invalidate];
*timer = nil;
*timer = [NSTimer scheduledTimerWithTimeInterval:interval target:self
selector:method userInfo:nil repeats:YES];
}
-(void)stopResponseTimer:(NSTimer **) timer {
NSLog(#"STOP TIMER");
[*timer invalidate];
*timer = nil;
}
then invoke it like
[self startResponseTimer:&launchTimer];
[self stopResponseTimer:&launchTimer];
This should make sure that you retain the right NSTimer object.
NOTE:It is always a good idea to check a pointer to a pointer to an object for NULL in a public method