防止按钮在短时间内被多次点击

- (void)buttonClicked:(UIButton *)btn
{
// 在0.2秒时间间隔内多次点击只响应一次点击事件, todoSomething就是具体要实现的方法
    [[self class] cancelPreviousPerformRequestsWithTarget:self selector:@selector(todoSomething:) object:btn];
    [self performSelector:@selector(todoSomething:) withObject:btn afterDelay:0.2f];
}

- (void)todoSomething:(UIButton *)btn
{
    
}