In object C
Define a class called XYPoint that will hold a Cartesian
coordinate (x, y), where x and y are integers. Define methods to
individually set the x and y coordinates of your new point and
retrieve their values. Write an Objective-C program to implement
your new class and test it (main section of the file). Your test
program needs to create two instances of your class. Make sure your
program test prints out the values that you have...