IOS学习笔记十(多态)

1、多态

相同类型调用同一个方法呈现多种不同的行为特征就是多态

当子类对象直接赋值给父类指针变量，父类 *p = [子类 new];，运行类型是子类，编译类型是父类，所以p不能调用子类单独实现的方法，如果子类重写了父类方法，p调用的方法会是子类重写的方法

isKindOfClass:clazz

判断该对象是否为clazz或者其子类的实例

2、测试demo

KFBase.h

#import <Foundation/Foundation.h>

#ifndef KFBase_h
#define KFBase_h

@interface KFBase : NSObject
-(void)base;
-(void)test;
@end

#endif /* KFBase_h */

KFBase.m

#import <Foundation/Foundation.h>
#import "KFBase.h"

@implementation KFBase
-(void)base
{
    NSLog(@"parent base method");
}
-(void)test
{
    NSLog(@"parent test method");
}
@end

SubClass.h

#import "KFBase.h"

#ifndef Subclass_h
#define Subclass_h
@interface Subclass : KFBase
-(void)sub;
-(void)test;
@end

#endif /* Subclass_h */

SubClass.m

#import <Foundation/Foundation.h>
#import "Subclass.h"

@implementation Subclass
-(void)sub
{
     NSLog(@"child sub method");
}
-(void)test
{
     NSLog(@"chile test method");
}
@end

main.m

#import "KFBase.h"
#import "Subclass.h"

int main(int argc, char * argv[]) {
    @autoreleasepool {
        KFBase *base = [KFBase new];
        [base base];
        [base test];
        Subclass *sub = [Subclass new];
        [sub base];
        [sub test];
        [sub sub];
        
        KFBase *seBase = [Subclass new];
        [seBase base];
        [seBase test];
        //下面运行会编译出错
//        [seBase sub];
        id dy = seBase;
        [dy sub];
		NSLog(@"sub是KFBase的子类吗？%d",[sub isKindOfClass:[KFBase class]]);
    }
}

3、运行结果

parent base method
parent test method
parent base method
chile test method
child sub method
parent base method
chile test method
child sub method
sub是KFBase的子类吗？1