Question

I am facing some problem with UISlider programming.

1) style: I know we have to set the minimum and maximum images. I am just not sure what images and any image reference will be great ? I only want to change from blue to black !

2) also, my code for the UISlider is this :

in header file:

UISlider *slider;

in code file:

 //slider
 CGRect frame=CGRectMake(10, 70, 300, 10);
 photoSlider=[[UISlider alloc] initWithFrame:frame];
 photoSlider.minimumValue=0.0;
 photoSlider.maximumValue=90.0; //maximumPhotoImage
 photoSlider.continuous=NO;
 photoSlider.value=10.0;
 photoSlider.backgroundColor=[UIColor clearColor];
 //photoSlider

 [photoSlider addTarget:self action:@selector(updateImage:)   forControlEvents:UIControlEventValueChanged];
 [self.view addSubview:photoSlider];

- (void) updateImage:(id) sender  
{
   NSLog(@"val: %d",photoSlider.value);
}

The values that I get from the function are 0 at both ends and very large value in between (both positive and negative…random values).

Can anyone kindly help me out ? Thanks.

Answer 1

For part 1, to replace the default blue part of the slider track with black, you could take a snapshot of the default blue track and convert it to a darker grayscale like this (only need the left end and 1 pixel of the stretchable part):

and call setMinimumTrackImage:forState::

UIImage *minTrackImg = [[UIImage imageNamed:@"MinimumTrackImage.png"] 
    stretchableImageWithLeftCapWidth:4 topCapHeight:0];
[photoSlider setMinimumTrackImage:minTrackImg forState:UIControlStateNormal];

For part 2, the values logged don’t make sense because the value property is of type float and you need to use %f instead of %d (see String Format Specifiers):

NSLog(@"val: %f",photoSlider.value);