Question

This question may be very specific, but I’m new to all this and really need some help.

I’m building an iPhone synth app.
I am using DCSliders an DCKnobs (they look nicer than the standard UISliders).

https://github.com/domesticcatsoftware/DCControls#readme

I am also working with libpd (a Pure Data library) so the audio DSP is handled by an embedded Pure Data patch.

https://gitorious.org/pdlib

I have got multiple DCSliders and DCKnobs in my interface. I am able to send control values from the sliders/knobs to Pure Data by making a class the delegate of the DCSlider…

- (void)loadView {
  [super loadView];
  self.mySlider = [[[DCSlider alloc] initWithDelegate:self] autorelease];
  self.mySlider.frame = CGRectMake(10.0, 10.0, 20.0, 120.0);

  [self.view addSubview:self.mySlider];
}

Then I implement a method to send control values to a receiver in Pure Data…

- (void)controlValueDidChange:(float)value sender:(id)sender {  
    [PdBase sendFloat:value toReceiver:@"beatvol"];
}

This all works ok.

The problem is that all of the sliders are sending the same control values.

How do I get each of the DCSliders to send independent control values to different receivers in Pure Data?

Answer 1

You need to assign a tag to your sliders. Then in controlValueDidChange: you need to get that tag and do your actions according to the tags:

- (void)loadView 
{
    [super loadView];
    mySlider = [[[DCSlider alloc] initWithDelegate:self] autorelease];
    mySlider.frame = CGRectMake(10.0, 10.0, 20.0, 120.0);
    mySlider.tag = 0;
    [self.view addSubview: mySlider];
}
- (void)controlValueDidChange:(float)value sender:(id)sender 
{  
    DCSlider * slider = (DCSlider *)sender;

    switch (slider.tag) 
    {
        case 0: 
        { 
            [PdBase sendFloat:value toReceiver:@"beatvol"];
        }
            break;
        case 1: 
        { 
            /*  do something for the 2nd slider  */;
        }
            break;
    }        
}