UIAlertView显示后自动消失

UIAlertView *msgAlertView = [[UIAlertView alloc] initWithTitle:nil message:@"2s后自动消失" delegate:nil cancelButtonTitle:nil otherButtonTitles:nil, nil];            [msgAlertView show];            [self performSelector:@selector(dimissAlertView:) withObject:msgAlertView afterDelay:2.0];

- (void)dimissAlertView:(UIAlertView *)alertView{    if(alertView) {        [alertView dismissWithClickedButtonIndex:[alertView cancelButtonIndex] animated:YES];    }}