Objective-C Runtime

Runtime

Working with Classes

1. class_getName
   返回类的名字

const char  * name=class_getName([Person class]);
NSLog(@"name=%s",name);
NSString *userName=[NSString stringWithUTF8String:name];
NSLog(@"userName=%@",userName);

2. class_getSuperclass
   返回父类的类的类型(class)

Class aclass = class_getSuperclass([Student class]);
    const char * name = class_getName(aclass);
    NSLog(@"name=%s",name);
    NSString *userName=[NSString stringWithUTF8String:name];
    NSLog(@"userName=%@",userName);

3. class_isMetaClass
   返回该类是否是元类

BOOL isMeta = class_isMetaClass([NSObject class]);

4. class_getInstanceSize
   返回该类实例的大小

size_t size = class_getInstanceSize([Person class]);
    NSLog(@"%zu",size);

5. class_getInstanceVariable
   返回实例变量的Ivar

Ivar ivar = class_getInstanceVariable([Person class],"_name");
    const char * ivar_name=ivar_getName(ivar);
    NSLog(@"ivar_name = %@",[NSString stringWithUTF8String:ivar_name]);

6. class_addIvar
   给类添加成员变量

• 该方法不能给已经存在的类添加成员变量
• 该方法只能在 objc_allocateClassPair方法之后,objc_registerClassPair这个方法之前调用

BOOL class_addIvar(Class cls, const char *name, size_t size, uint8_t alignment, const char *types);

Class People = objc_allocateClassPair([NSObject class], "People", 0);
    
class_addIvar(People, "_name", sizeof(NSString *), 0, @encode(NSString *));
class_addIvar(People, "_age", sizeof(NSNumber *), 0, @encode(NSNumber *));

objc_registerClassPair(People);

7. class_addProperty
   给类添加属性

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

objc_property_attribute_t attribute1 = {"T", @encode(NSString *)};
objc_property_attribute_t attribute2 = {"N", ""};
objc_property_attribute_t attribute3 = {"&", ""};
objc_property_attribute_t attribute[] = {attribute1, attribute2, attribute3};
class_addProperty([HCBase class], "sb", attribute, 3);

8. class_addMethod
   给已经存在的类添加实例方法

_aperson =[[Person alloc]init];
    BOOL sucess = class_addMethod([Person class],(NSSelectorFromString(@"methodName")),class_getMethodImplementation([self class], @selector(printtext:)), "v@:@");
    if(sucess){
        [_aperson performSelector:(NSSelectorFromString(@"methodName")) withObject:@"hahahhahah" afterDelay:0];
    }

9. class_addProtocol
   给一个已有的类添加协议

BOOL class_addProtocol(Class cls, Protocol *protocol);

BOOL sucess = class_addProtocol([Person class],_test);

10. class_copyIvarList
    获取一个类的成员变量列表的一个拷贝

Ivar  _Nonnull * class_copyIvarList(Class cls, unsigned int *outCount);

unsigned int count;
    Ivar * ivars =  class_copyIvarList([Person class], &count);
    for (int i=0; i<count; i++) {
        NSLog(@"-----%@",[NSString stringWithUTF8String:ivar_getName(ivars[i])]);
    }
    free(ivars);

• outcount为成员变量的个数
• 只会显示当前类的成员变量,不包括父类的任何成员变量
• 你必须使用free()方法释放ivars数组

11. class_getIvarLayout
    获取类所有的strong修饰符数组

const uint8_t * class_getIvarLayout(Class cls);

const uint8_t *array_s = class_getIvarLayout([Person class]);
   int i = 0;
   uint8_t value_s = array_s[i];
   while (value_s != 0x0) {
       printf("\\x%02x\n", value_s);
       value_s = array_s[++i];
   }

12. class_setIvarLayout
    设置Ivar 属性修饰符

void class_setIvarLayout(Class cls, const uint8_t *layout);

13. class_getWeakIvarLayout
    获取类所有的weak修饰符数组

const uint8_t * class_getWeakIvarLayout(Class cls);

const uint8_t *array_s1 = class_getWeakIvarLayout([Person class]);
    int j = 0;
    uint8_t value_s1 = array_s1[j];
    while (value_s1 != 0x0) {
        printf("\\x%02x\n", value_s1);
        value_s1 = array_s1[++j];
    }

14. class_setWeakIvarLayout
    设置Ivar weak修饰符

void class_setWeakIvarLayout(Class cls, const uint8_t *layout);

15. class_getProperty
    获取指定属性

objc_property_t class_getProperty(Class cls, const char *name);

objc_property_t  propert_t = class_getProperty([Person class],"name");
    const char * properName = property_getName(propert_t);
    NSLog(@"--%@",[NSString stringWithUTF8String:properName]);

16. class_copyPropertyList
    获取一个类的属性列表的一个拷贝

objc_property_t  _Nonnull * class_copyPropertyList(Class cls, unsigned int *outCount);

unsigned int count;
    objc_property_t *array = class_copyPropertyList([Person class], &count);
    for (int i=0; i<count; i++) {
        const char * name = property_getName(array[i]);
        NSLog(@"---%@",[NSString stringWithUTF8String:name]);
    }

17. class_getInstanceMethod
    获取类中的指定实例的 Method

Method class_getInstanceMethod(Class cls, SEL name);

Method method = class_getInstanceMethod([Person class], @selector(printName));
    NSLog(@"---%@",[NSString stringWithUTF8String:(method_getName(method))]);

18. class_getClassMethod
    获取类中指定的类的Method

Method class_getClassMethod(Class cls, SEL name);

19. class_copyMethodList
    获取当前类的所有实例方法的拷贝

Method  _Nonnull * class_copyMethodList(Class cls, unsigned int *outCount);

unsigned int count;
    Method *methods = class_copyMethodList([Person class], &count);
    for (int i = 0; i < count; i++) {
        const char *methodName =sel_getName((method_getName(methods[i])));
        NSLog(@"---methodname=%@",[NSString stringWithUTF8String:methodName]);
    }

20. class_replaceMethod
    替换类中方法的实现地址

IMP class_replaceMethod(Class cls, SEL name, IMP imp, const char *types);

Method originalMethod = class_getInstanceMethod([Person class], @selector(printName));
    Method swizzledMethod = class_getInstanceMethod([Person class], @selector(printAge));
    class_replaceMethod([Person class],
                        @selector(printAge),
                        method_getImplementation(originalMethod),
                        method_getTypeEncoding(originalMethod));
    Person *person = [[Person alloc]init];
    [person printAge];

• 返回替换后旧的IMP
• types类型可以使用该方法获取:method_getTypeEncoding()
• 如果要替换的方法不存在,首先需要使用class_addMethod添加方法,然后在去替换

21. class_getMethodImplementation
    获取类中指定方法的方法指针

IMP class_getMethodImplementation(Class cls, SEL name);

 IMP methodImp = class_getMethodImplementation([Person class], @selector(printName));
    NSLog(@"%ld",(long)methodImp);

22. class_respondsToSelector
    是否类的实例能够响应该方法

BOOL class_respondsToSelector(Class cls, SEL sel);

可使用下列方法替换:

• respondsToSelector:
• instancesRespondToSelector:

23. class_replaceProperty
    替换类中的一个属性

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

- (void)class_replaceProperty:(Class)class class_name:(const char *)class_name replace_name:(const char *)replace_name{
    objc_property_attribute_t type = { "T", "@\"NSString\"" };
    objc_property_attribute_t ownership = { "C", "" }; // C = copy
    objc_property_attribute_t backingivar  = { "V", replace_name };
    objc_property_attribute_t attrs[] = { type, ownership, backingivar };
    class_replaceProperty(class, class_name, attrs, 3);
}

24. class_conformsToProtocol
    判断该类是否遵循协议

BOOL class_conformsToProtocol(Class cls, Protocol *protocol);

可用NSObject里边的conformsToProtocol:替换

Adding Classes

1. objc_allocateClassPair
   创建一个新的类和元类

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

extraBytes参数通常为0

• 实例变量及实例方法添加到类中
• 类方法添加至元类中

2. objc_disposeClassPair
   销毁一个类及它的的元类

void objc_disposeClassPair(Class cls);

当该类的实例及子类存在时,不能调用该方法

3. objc_registerClassPair
   注册一个类

void objc_registerClassPair(Class cls);

Instantiating Classes

1. class_createInstance
   创建一个类的实例,且默认分配内存空间

id class_createInstance(Class cls, size_t extraBytes);

2. objc_constructInstance
   幢一个类的实例,且分配实例的字节大小

id objc_constructInstance(Class cls, void *bytes);

3. objc_destructInstance
   销毁了一个类的实例没有释放内存并删除任何相关的引用

void * objc_destructInstance(id obj);

Working with Instances

1. object_copy
   返回一个对象的拷贝

id object_copy(id obj, size_t size);

2. object_dispose
   释放一个对象的内存

id object_dispose(id obj);

3. object_setInstanceVariable
   修改一个类的实例的变量值

Ivar object_setInstanceVariable(id obj, const char *name, void *value)

Person *person =[[Person alloc]init];
    NSString * string = @"xiao hong";
    Ivar ivar = object_setInstanceVariable(person,"_name",&string);
    [person printName];

ARC环境下不可用

4. object_getInstanceVariable
   获取一个实例的变量值

Ivar object_getInstanceVariable(id obj, const char *name, void * _Nullable *outValue);

Person *person =[[Person alloc]init];
    NSString *name;
    object_getInstanceVariable(person,"_name",&name);
    NSLog(@"name = %@",name);

ARC环境下不可用

5. object_getClassName
   获取一个对象的类名

const char * object_getClassName(id obj);

6. object_getClass
   返回一个对象的Class

Class object_getClass(id obj);

Person *person =[[Person alloc]init];
    Class aclass = object_getClass(person);
    NSLog(@"---aclass = %@",[NSString stringWithUTF8String:(class_getName(aclass))]);

7. object_setClass
   修改实例的类 返回之前的类的Class

Class object_setClass(id obj, Class cls);

Person *person =[[Person alloc]init];
    Class aclass = object_setClass(person, [Student class]);
    NSLog(@"---aclass = %@",[NSString stringWithUTF8String:(class_getName(aclass))]);
    NSLog(@"person = %@",[NSString stringWithUTF8String:object_getClassName(person)]);

Working with Instance Variables

1. ivar_getName
   返回变量的名字

const char * ivar_getName(Ivar v);

2. ivar_getTypeEncoding
   返回string类型的变量类型

const char * ivar_getTypeEncoding(Ivar v);

3. ivar_getOffset
   返回变量的偏移量

ptrdiff_t ivar_getOffset(Ivar v);

Associative References

1. objc_setAssociatedObject
   给一个对象添加协议键值

void objc_setAssociatedObject(id object, const void *key, id value, objc_AssociationPolicy policy);

objc_setAssociatedObject(self,&flashColorKey, flashColor, OBJC_ASSOCIATION_RETAIN_NONATOMIC);

给分类添加协议属性时用到

2. objc_getAssociatedObject
   获取对象的协议值

id objc_getAssociatedObject(id object, const void *key);

给分类添加协议属性时用到

3. objc_removeAssociatedObjects
   移除对象的所有协议

void objc_removeAssociatedObjects(id object);

一般通过将value设置成nil来移除协议关系,如果用该方法会影响别的协议

Sending Messages

1. objc_msgSend

id objc_msgSend(id self, SEL op, ...);

Person *person =[[Person alloc]init];
    [person printName];
    ((void (*) (id, SEL)) objc_msgSend)(person, sel_registerName("printName"));
    NSLog(@"---------%@",[person getPrintName:@"yangguoqiang"]);
    NSString *name=((NSString * (*) (id, SEL,NSString *)) objc_msgSend)(person, sel_registerName("getPrintName:"),@"yangguoqiang");
    NSLog(@"---------%@",name);
    dog *adog = [person getDogWithAge:10 andLevel:1];
    NSLog(@"---%@",[NSString stringWithUTF8String:object_getClassName(adog)]);
    dog *twoDog = ((dog * (*) (id, SEL,NSInteger,NSInteger)) objc_msgSend)(person, sel_registerName("getDogWithAge:andLevel:"),10,1);
    NSLog(@"---%@",[NSString stringWithUTF8String:object_getClassName(twoDog)]);

Working with Methods

1. method_invoke
   方法调用

id method_invoke(id receiver, Method m, ...);

Person *person =[[Person alloc]init];
    [person printName];
    Method method = class_getInstanceMethod([Person class], @selector(printName));
    method_invoke(person,method);

2. method_invoke_stret
   方法调用返回一个结构体

void method_invoke_stret(id receiver, Method m, ...);

3. method_getName
   通过一个Method类型返回SEL类型

SEL method_getName(Method m);

Person *person =[[Person alloc]init];
    [person printName];
    Method method = class_getInstanceMethod([Person class], @selector(printName));
    SEL seletor = method_getName(method);
    NSLog(@"----%@",[NSString stringWithUTF8String:sel_getName(seletor)]);

4. method_getImplementation
   通过Method对象获取方法的IMP地址

IMP method_getImplementation(Method m);

5. method_getTypeEncoding
   通过Method的对象返回一个字符串,描述方法的参数及返回值

const char * method_getTypeEncoding(Method m);

Method method = class_getInstanceMethod([Person class], @selector(printName));
    NSLog(@"----%@",[NSString stringWithUTF8String:method_getTypeEncoding(method)]);

6. method_copyReturnType
   通过Method的对象拷贝返回值的字符串 要使用free()方法释放

char * method_copyReturnType(Method m);

 Method method = class_getInstanceMethod([Person class], @selector(getPrintName:));
    NSLog(@"----%@",[NSString stringWithUTF8String:method_copyReturnType(method)]);

7. method_copyArgumentType
   按index返回字符串参数的类型 要使用free()方法释放

char * method_copyArgumentType(Method m, unsigned int index);

Method method = class_getInstanceMethod([Person class], @selector(getPrintName:));
    NSLog(@"----%@",[NSString stringWithUTF8String:method_copyArgumentType(method,0)]);

8. method_getNumberOfArguments
   返回参数的个数

unsigned int method_getNumberOfArguments(Method m);

9. method_setImplementation
   给方法设置新的实现地址 返回旧的方法地址

IMP method_setImplementation(Method m, IMP imp);

10. method_exchangeImplementations
    交互两个方法的实现地址

void method_exchangeImplementations(Method m1, Method m2);

Person *person =[[Person alloc]init];
    [person printName];
    Method method1 = class_getInstanceMethod([Person class], @selector(printName));
    Method method2 = class_getInstanceMethod([Person class], @selector(printAge));
    method_exchangeImplementations(method1,method2);
    [person printName];

Working with Libraries

1. objc_copyImageNames
   获取所有的Objective-C 动态库及静态库名称的字符串数组

const char * _Nonnull * objc_copyImageNames(unsigned int *outCount);

unsigned int count;
    const char ** names = objc_copyImageNames(&count);
    for (int i= 0; i<count; i++) {
        NSLog(@"-----%@",[NSString stringWithUTF8String:names[i]]);
    }

2. class_getImageName
   返回一个字符串路径,显示该类属于哪个库

const char * class_getImageName(Class cls);

const char * name = class_getImageName([Person class]);
    NSLog(@"-----%@",[NSString stringWithUTF8String:name]);

3. objc_copyClassNamesForImage
   获取指点库中所有类的字符数组名

const char * _Nonnull * objc_copyClassNamesForImage(const char *image, unsigned int *outCount);

Working with Selectors

1. sel_getName
   获取SEL类型方法的字符串名称

const char * sel_getName(SEL sel);

2. sel_registerName
   在runtime系统中注册方法

SEL sel_registerName(const char *str);

3. sel_getUid
   在runtime系统中注册方法

SEL sel_getUid(const char *str);

4. sel_isEqual
   判断两个方法是不是相等

BOOL sel_isEqual(SEL lhs, SEL rhs);

Working with Protocols

1. objc_getProtocol
   Returns a specified protocol.
2. objc_copyProtocolList
   Returns an array of all the protocols known to the runtime.
3. objc_allocateProtocol
   Creates a new protocol instance.
4. objc_registerProtocol
   Registers a newly created protocol with the Objective-C runtime.
5. protocol_addMethodDescription
   Adds a method to a protocol.
6. protocol_addProtocol
   Adds a registered protocol to another protocol that is under construction.

Working with Properties

1. property_getName
   返回属性的字符名称

const char * property_getName(objc_property_t property);

2. property_getAttributes
   返回属性的字符

Returns the attribute string of a property.

3. property_copyAttributeValue
   Returns the value of a property attribute given the attribute name.

char * property_copyAttributeValue(objc_property_t property, const char *attributeName);