对象在运行时获取其类型的能力称为内省。内省可以有多种方法实现。
判断对象类型
-(BOOL) isKindOfClass: classObj判断是否是这个类或者这个类的子类的实例
-(BOOL) isMemberOfClass: classObj 判断是否是这个类的实例
新建Person和Teacher类
Person
//
// Person.h
// DynamicType
//
// Created by Michael on 2016/9/27.
// Copyright © 2016年 Michael. All rights reserved.
//
#import <Foundation/Foundation.h>
@interface Person : NSObject {
NSString *name;
}
-(void) setName:(NSString*) n;
@end
//
// Person.m
// DynamicType
//
// Created by Michael on 2016/9/27.
// Copyright © 2016年 Michael. All rights reserved.
//
#import "Person.h"
@implementation Person
-(void) setName:(NSString*) n {
name = n;
}
@end
Teacher
//
// Teacher.h
// DynamicType
//
// Created by Michael on 2016/9/27.
// Copyright © 2016年 Michael. All rights reserved.
//
#import "Person.h"
//继承Person
@interface Teacher : Person
-(void) teach;
@end
//
// Teacher.m
// DynamicType
//
// Created by Michael on 2016/9/27.
// Copyright © 2016年 Michael. All rights reserved.
//
#import "Teacher.h"
@implementation Teacher
-(void) teach {
NSLog(@"%@教数学",name);
}
@end
isMemberOfClass
Person *person = [[Person alloc] init];
Teacher *teaher = [[Teacher alloc] init];
//1.isMemberOfClass判断是否是属于这类的实例,是否跟父类有关系他不管
//yes
if ([teaher isMemberOfClass:[Teacher class]]) {
NSLog(@"teacher Teacher类的成员");
}
//no
if ([teaher isMemberOfClass:[Person class]]) {
NSLog(@"teacher Person类的成员");
}
//no
if ([teaher isMemberOfClass:[NSObject class]]) {
NSLog(@"teacher NSObject类的成员");
}
isKindOfClass
//2.isKindOfClass判断是否是其子类
//yes
if ([teaher isKindOfClass:[Teacher class]]) {
NSLog(@"teacher 是Teacher类或子类");
}
//yes
if ([teaher isKindOfClass:[Person class]]) {
NSLog(@"teacher 是Person类或子类");
}
//yes
if ([teaher isKindOfClass:[NSObject class]]) {
NSLog(@"teacher 是NSObject类或子类");
}
判断对象方法
-(BOOL) respondsToSelector: selector 判读实例是否有这样方法
+(BOOL) instancesRespondToSelector: 判断类是否有这个方法。此方法是类方法,不能用在类的对象
respondsToSelector
//3.respondsToSelector判断示例是否有这个方法
if ([teaher respondsToSelector:@selector(setName:)]) {
NSLog(@"有此方法");
}
if ([teaher respondsToSelector:@selector(setAge)] == NO) {
NSLog(@"无此方法");
}
instancesRespondToSelector
//4.instancesRespondToSelector判断类中是否有该方法,不能用在类的对象
if ([Person instancesRespondToSelector:@selector(setName:)]) {
NSLog(@"Person 有此方法");
}
if ([Teacher instancesRespondToSelector:@selector(teach)]) {
NSLog(@"Teacher 有此方法");
}
if ([Teacher instancesRespondToSelector:@selector(setName:)]) {
NSLog(@"Teacher 有此方法");
}
Objective-C的id类型
在 Objective-C 中,id类型类似于(void*) ,可以指向任何类的实例。而不需要强制转换。
Teacher *teaher = [[Teacher alloc] init];
id t = teaher; //id指向Teacher类
[t setName:@"liuguoquan"];
[t teach];
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来通知其他用户。