How can I pass event through @selector in NSTimer?

You cannot pass data through a selector. A selector is simply the name of a method, not a call to it. When used with a timer, the selector you pass should accept one argument, and that argument will be the timer which caused it.

However, you can pass data to the called method using the userInfo parameter. You pass the event in that parameter, and retrieve it using the userInfo method on the timer.

If you want to use a timer to trigger a method that takes parameters, use -scheduledTimerWithTimeInterval:invocation:repeats: with an appropriate instance of NSInvocation in place of one of the methods that take selectors.

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