Question

I’m implementing a UISlider that allows users to select a position on a football field. The idea of the slider is for the field to scroll forward when the slider value is above a certain value (the section with the arrow).

My issue is that I can only respond to the slider on UIControlEventValueChanged – so the field will only scroll forward when the user is actually moving the slider. I’d like it to move forward as long as the value is above a certain amount.

Any idea how I can do this? (I’m open to any suggestion, including an implementation that does not use a UISlider, composite implementations, etc.).

Here’s the implementation:

Answer 1

The easiest way to handle this is with a timer. Add an NSTimer instance variable to your class, named—for the sake of the example below—moveTimer, then set up something like this:

- (void)sliderChanged:(UISlider *)slider
{
    if(slider.value > 5)
    {
        if(moveTimer == nil)
        {
            moveTimer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self action:@selector(move) repeats:YES];
        }
    }
    else
    {
        if(moveTimer != nil)
        {
            [moveTimer invalidate];
            moveTimer = nil;
        }
    }
}

- (void)move
{
    // update the background behind your slider
}