cancelPreviousPerformRequests with arbitrary object

Question

I am scheduling a method to be called with an object in the near future and the object is just a random NSString that is gone as soon as I schedule the selector.

So I may say something like:

[self performSelector:@selector(runMethod:) withObject:@"randomString" afterDelay:1.0f];

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If I need to cancel this BEFORE it fires documentation says to use:

[NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(runMethod:) object:***];

• • *The only issue is I don't know what the "object" is, it was just a random string that doesn't exist anymore and has been released by ARC by now. How can I cancel any scheduled methods with a specific selector (in my case runMethod:) but without knowing the "object"?

Is there any way to get a list of all scheduled functions in the NSRunLoop and just iterate through them with a for loop looking for ones with specific selector names?

Answer 1

If you need to cancel things you should organise a better way to schedule them such that you can actually check what it scheduled and the details associated with it. A potential solution would be a custom class with a set of parameters. Internally this class runs a timer which executes the action at the specified fire time. An array of instances of this class would be trivial to search and cancel arbitrary items from.

Answer 2

If, as I understand, the randomString is useless for you, then pass nil to both performSelector... and cancelPreviousPerform...

Like this:

[NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(runMethod) object:nil];

[self performSelector:@selector(runMethod) withObject:nil afterDelay:1.0f];