How to dismiss UIActionSheet automatically

I have a requirem开发者_StackOverflow中文版ent where i am showing actionSheet but in case user does not dismiss this actionsheet by selecting one of the option, i want to dismiss this automatically by program on a particular event. Any idea guys, how can i dismiss this actionsheet progratically?

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Use:

- (void)dismissWithClickedButtonIndex:(NSInteger)buttonIndex animated:(BOOL)animated