Can't rewrite Setter methods in subclasses - objective-c

Question

I am creating a new class in Obj-C called “Complex” which will deal with complex numbers.
I have 4 instance variables declared in the .h as follows:
#property (nonatomic) double re, im;
#property (nonatomic) double mod, arg;
and later, they are synthesized in the .m file:
#synthesize re, im; //real / imaginary parts
#synthesize mod, arg; //modulus / argument parts
In the complex class, I have many methods which involve functions/operations with complex numbers. Since each of these will only modify the complex number in either Cartesian/Polar form, I need a way to update the other form after a function.
I decided to do this by modifying the setter methods for all 4 variables (which is why I chose them to be nonatomic).
I’ve finished making this class, and everything works fine. However, I now would like to create 2 subclasses of Complex which would be CComplex (Cartesian) and PComplex (Polar). These subclasses would only work with the Cartesian/Polar instance variables.
It would be ideal to use these classes when you don’t need to interact with the other form as it increases speed when you are performing functions with Complex numbers several thousand/million times a second (Since the Updater in the setter methods would be skipped).
The problem I’m coming across is that I cannot rewrite the setter method in the subclasses, and nor can I recreate the instance variables (with the same names).
Can someone help me with this problem please? Thanks
Edit: Here's the relevant code:
Here's how I tried to implement the setter methods in my subclasses at first:
.h
#interface CComplex : Complex
#property (nonatomic) double re, im;
//
////Setter Methods
-(void) setRe:(double)r;
-(void) setIm:(double)i;
////
//
#end
#interface PComplex : Complex
#property (nonatomic) double mod, arg;
//
////Setter Methods
-(void) setMod:(double)m;
-(void) setArg:(double)a;
////
//
#end
.mm
#implementation CComplex
#synthesize re, im;
//
////Setter Methods
-(void) setRe:(double)r {
re = r;
}
-(void) setIm:(double)i {
im = i;
}
////
//
#end
#implementation PComplex
#synthesize mod, arg;
//
////Setter Methods
-(void) setMod:(double)m {
mod = m;
}
-(void) setArg:(double)a {
arg = a;
}
////
//
#end

Answer 1

I don’t know how you are overriding the setter but the common case should be:
#synthesize = re = _re;
- (void)setRe:(double)re {
// your code
_re = re;
}
Or instead of overriding the setter you can use lazy instantiation:
- (double)re {
if(!_re) {
_re = …// your code
}
return _re
}
To declare a public property, put in your class Ex: MyClass.h interface (not in the .m):
#import <Foundation/Foundation.h>
#interface MyClass : NSObject
#property (nonatomic) double re;
#end
To set a superclass property in a subclass you don't have to synthesize or redefine a property in a subclass:
super.re = ...;