Question

I’m tring to convert the following 3 methods from java-actionscript to Objective C.
Part of my confusion I think is not knowing what Number types, primitives I should be using. ie in actionscript you have only Number, int, and uint. These are the 3 functions I am trying to convert

 public function normalize(value:Number, minimum:Number, maximum:Number):Number
    {
        return (value - minimum) / (maximum - minimum);
    }

    public function interpolate(normValue:Number, minimum:Number, maximum:Number):Number
    {
        return minimum + (maximum - minimum) * normValue;
    }

    public function map(value:Number, min1:Number, max1:Number, min2:Number, max2:Number):Number
    {
        return interpolate( normalize(value, min1, max1), min2, max2);
    }

This is what I have so far

-(float) normalize:(float*)value 
 withMinimumValue:(float*)minimum 
 withMaximumValue:(float*)maximum
 {
 return (value - minimum) / (maximum - minimum);
 }

-(float) interpolate:(float*)normValue
  withMinimumValue:(float*)minimum 
  withMaximumValue:(float*)maximum
 {
return minimum + (maximum - minimum) * normValue;
 }

-(float) map:(float*)value 
 withMinimumValue1:(float*)min1 
 withMaximumValue1:(float*)max1 
 withMinimumValue2:(float*)min2 
 withMaximumValue2:(float*)max2
 {
return interpolate( normalize(value, min1, max1), min2, max2);
 }

Answer 1

• If you’re looking for a primitive type (not an object) that can handle non-integer values, float is probably fine (or CGFloat, as suggested by Chris)

• unless your functions need to modify their arguments, you want the arguments to be just float not float *.

• you are mixing up Objective-C message passing and plain C function invocation syntax: your example declares them as instance methods, but you’re calling them like a function (won’t work).

To match your declarations, the invocation would look something like:

return [self interpolate:
           [self normalize:value withMinimumValue:min1 withMaximumValue:max1]
           withMinimumValue:min2
           withMaximumValue:max2];

• Because your interpolate, normalize, and map methods do not rely on any variables from the current object instance, they might be better off as objective-C class methods (or even as plain C functions).