NSObject头文件解析

来源：互联网发布：网络纠纷管辖问题编辑：程序博客网时间：2024/05/19 23:57

本章接着NSObject头文件解析 / 消息机制 / Runtime解读(一)写

给类添加属性:

BOOL class_addProperty(Class cls, const char *name, const objc_property_attribute_t *attributes, unsigned int attributeCount)

其中有一个参数我们再在上一篇中提到过

typedef struct {

const char *name; /**< The name of the attribute */

const char *value; /**< The value of the attribute (usually empty) */

} objc_property_attribute_t;

我们看下常见的赋值

常用attributenamevaluenonatomic"N"""strong/retain"&"""weak"W"""属性的类型type"T""@TypeName", eg"@\"NSString\""属性对应的实例变量Ivar"V""Ivar_name", eg "_name"readonly"R"""getter"G""GetterName", eg"isRight"setter"S""SetterName", eg"setName"assign/atomic默认即为assign和retain 　　

例子:

- (void)viewDidLoad {        [super viewDidLoad];        //创建一个对象    ClassA *aClass = [ClassA new];            //创建一个attributes    objc_property_attribute_t nonatmoic = {"N", ""};    objc_property_attribute_t strong    = {"&", ""};    objc_property_attribute_t type      = {"T", "@\"NSString\""};    objc_property_attribute_t ivar      = {"V", "_name"};        objc_property_attribute_t attributes[] = {nonatmoic, strong, type, ivar, getter, setter};        //给对象类添加属性    BOOL result = class_addProperty([aClass class], "name", attributes, 4);        if (result) {                NSLog(@"添加成功");    } else {                NSLog(@"添加失败");    }        //读取添加属性    objc_property_t property = class_getProperty([aClass class], "name");        //获取添加的属性的名称    NSString *propertyName = [NSString stringWithUTF8String:property_getName(property)];        //打印获取到的属性名    NSLog(@"获取到的属性名为: %@", propertyName);    }

运行结果:

2017-02-03 15:52:01.949 RunTimeDemo[786:37263] 添加成功2017-02-03 15:52:01.949 RunTimeDemo[786:37263] 获取到的属性名为: name

替换属性:

void class_replaceProperty(Class cls, const char *name, const objc_property_attribute_t *attributes, unsigned int attributeCount)

例子:

//创建一个对象    ClassA *aClass = [ClassA new];            //创建一个attributes    objc_property_attribute_t nonatmoic = {"N", ""};    objc_property_attribute_t strong    = {"&", ""};    objc_property_attribute_t type      = {"T", "@\"NSString\""};    objc_property_attribute_t ivar      = {"V", "_name"};        objc_property_attribute_t attributes[] = {nonatmoic, strong, type, ivar};        //替换属性    class_replaceProperty([aClass class], "name", attributes, 4);

运行时创建新类:

Class objc_allocateClassPair(Class superclass, const char *name,                                          size_t extraBytes)

注册创建的新类:

void objc_registerClassPair(Class cls)

例子:

void printA(){        NSLog(@"Print A");}- (void)viewDidLoad {        [super viewDidLoad];        //创新新类    Class NewClass = objc_allocateClassPair([NSObject class], "NewObject", 0);        //注册类    objc_registerClassPair(NewClass);        //给类添加方法    class_addMethod([NewClass class], @selector(printA), (IMP)printA, "v@:");        //创建实例    id ob = [NewClass new];        //实例执行方法    [ob printA];    }

运行结果:

2017-02-03 18:11:34.091 RunTimeDemo[1114:96700] Print A

先Mark在这里, 后面会继续更新

0 0