// THE FIRST IF STATEMENT IS WHAT GETS SELECTED
// newValue = 0.93
// colorRange = {0.10, 0.20, 0.80, 0.90 }
NSNumberFormatter *format = [[NSNumberFormatter alloc] init];
[format setNumberStyle:NSNumberFormatterDecimalStyle];
NSNumber *newValue = [format numberFromString:value];
[format release];

if (newValue < [colorRange objectAtIndex:0]) {
    // Red background
    selectedButton.backgroundColor = [UIColor redColor];
}
else if (newValue > [colorRange objectAtIndex:0] && newValue < [colorRange objectAtIndex:1]) {
    // White background
    selectedButton.backgroundColor = [UIColor whiteColor];
}
else if (newValue > [colorRange objectAtIndex:1] && newValue < [colorRange objectAtIndex:2]) {
    // Black background
    selectedButton.backgroundColor = [UIColor blackColor];
}
else if (newValue > [colorRange objectAtIndex:2] && newValue < [colorRange objectAtIndex:3]) {
    // Blue background
    selectedButton.backgroundColor = [UIColor blueColor];
}
else {
    // Green background
    selectedButton.backgroundColor = [UIColor greenColor];
}

if ([newValue compare:[colorRange objectAtIndex:0]] == NSOrderedAscending) {
    // Red background
    selectedButton.backgroundColor = [UIColor redColor];
}
...

if ([newValue floatVaue] < [colorRange objectAtIndex:0] floatValue])

newValue < [colorRange objectAtIndex:1]

NSArray *backgroundColours = @[ [UIColor redColor], [UIColor whiteColor], ...];
NSUInteger index = 0;
for(NSNumber *colour in colorRange)
{
    if([newValue compare:colour] == NSOrderedAscending)
    {
        selectedButton.backgroundColor = [backgroundColours objectAtIndex:index];
        break;
    }
    index++;
}

if ([newValue compare:[colorRange objectAtIndex:0]] == NSOrderedAscending) ...

if ([newValue floatValue]<[[color objectAtIndex:0] floatValue]