15、Objective-C 中的多态、动态类型和动态绑定

Objective-C 中的多态、动态类型和动态绑定

1. 多态：同名不同类

多态允许不同类的对象定义同名的方法。以 Complex 类为例，它用于表示复数。以下是 Complex 类的接口文件 Complex.h ：

// Interface file for Complex class
#import <Foundation/Foundation.h>
@interface Complex: NSObject
@property double real, imaginary;
-(void)   print;
-(void)   setReal: (double) a andImaginary: (double) b;
-(Complex *) add: (Complex *) f;
@end

实现文件 Complex.m 如下：

// Implementation file for Complex class
#import "Complex.h"
@implementation Complex
@synthesize real, imaginary;
-(void) print
{
    NSLog (@" %g + %gi ", real, imaginary);
}
-(void) setReal: (double) a andImaginary: (double) b
{
    r