dynamic binding

bind.m

#import <Foundation/Foundation.h>

@interface Square : NSObject
{
    float area;
}

- (void)calculateAreaOfSide: (CGFloat)side;
- (void)printArea;
@end

@implementation Square
- (void)calculateAreaOfSide: (CGFloat)side
{
    area = side * side;
}

- (void)printArea
{
    NSLog(@"The area of square is %f", area);
}
@end


@interface Rectangle : Square
- (void)calculateAreaOfLength: (CGFloat)length andBreadth: (CGFloat)breadth;
- (void)printArea;
@end

@implementation Rectangle
- (void)calculateAreaOfLength: (CGFloat)length andBreadth: (CGFloat)breadth
{
    area = length * breadth;
}

- (void)printArea
{
    NSLog(@"The area of Rectangle is %f", area);
}
@end

int main(int argc, char *argv[]) {
    Square *square = [[Square alloc]init];
    [square calculateAreaOfSide:10.0];

    Rectangle *rectangle = [[Rectangle alloc]init];
    [rectangle calculateAreaOfLength: 10.0 andBreadth:5.0];

    NSArray *shapes = [[NSArray alloc]initWithObjects: square, rectangle, nil];

    id  object1 = [shapes objectAtIndex:0];
    [object1 printArea];
    id object2 = [shapes objectAtIndex:1];
    [object2 printArea];

    return 0;
}