runtime 知识点

demo https://github.com/ZOYOOPlus/runtime2

// ViewController.m

// runtime

#import "ViewController.h"

#import "MyObject.h"

#import "UIView+TYView.h"

#import <objc/runtime.h>

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {// 1.类相关函数

// 得到类名 ViewController

NSLog(@"%s",class_getName([self class]));

// 父类类名

// This is superClass 0x10f426da0 isa指针地址

NSLog(@"This is superClass %p",class_getSuperclass([self class]));

// 是否是元类

// Is MateClass 0

NSLog(@"Is MateClass %d",class_isMetaClass([self class]));

// 实例变量大小

// 848

size_t a = class_getInstanceSize([self class]);

NSLog(@"%ld",a);

unsigned int outCount = 0;

MyObject *objtect = [[MyObject alloc] init];

Class cls = objtect.class;

//类名

NSLog(@"Class name %s",class_getName(cls));

//父类名字

NSLog(@"SuperClass name %s",class_getName(class_getSuperclass(cls)));

//是否元类

NSLog(@"Is MetaClass %@",(class_isMetaClass(cls))?@"":@"NOT");

//变量大小

NSLog(@"MyObject size %ld",class_getInstanceSize(cls));

//变量信息

Ivar string = class_getInstanceVariable(cls, "_string");

if (string != NULL) {

NSLog(@"MyObject instance messge %s",ivar_getName(string));

}

// 属性操作

objc_property_t *v = class_copyPropertyList(cls, &outCount);

for (NSInteger i = 0; i< outCount; i++) {

objc_property_t property = v[i];

NSLog(@"property is %s ",property_getName(property));

}

free(v);

//成员变量

Ivar *vars = class_copyIvarList(cls, &outCount);

for (NSInteger i =0; i< outCount; i++) {

Ivar ivar = vars[i];

NSLog(@"copyIvarList is %s is %ld",ivar_getName(ivar),i);

}

free(vars);

//方法操作

Method *methods = class_copyMethodList(cls, &outCount);

for (NSInteger i =0; i< outCount; i++) {

Method met = methods[i];

#pragma clang diagnostic ignored"-Wformat"

NSLog(@"Method is %s",method_getName(met));

}

free(methods);

// Format specifies type 'char *' but the argument has type 'SEL _Nonnull'

// 获取方法名

Method method = class_getInstanceMethod(cls,@selector(method1));

NSLog(@"Method name is %s",method_getName(method));

// 判断方法是否存在

#pragma clang diagnostic ignored"-Wundeclared-selector"

NSLog(@"Have you method %d",class_respondsToSelector(cls, @selector(method3WithArge1:arge2:)));

// 指向函数实现的指针，相当于方法的实现

IMP imp = class_getMethodImplementation(cls, @selector(method1));

imp();

//动态创建类

#pragma clang diagnostic ignored" -Wunused-variable"

// 注:运行时规定,只能在objc_allocateClassPair与objc_registerClassPair两个函数之间为类添加变量

// 1.添加一个自定义的类类名是MySubClass

// 父类class,类名,额外空间

Class myClass = objc_allocateClassPair(objtect.class, "MySubClass", 0);

// 2.增加方法，交换方法

//注: v@: 意思是 v是void @:没有返回参数

if( class_addMethod(myClass, @selector(mysubMethod1),(IMP)mysubMethod1, "v@:")){

class_replaceMethod(myClass, @selector(method1), (IMP)mysubMethod1,"v@:");

}

3.增加一个NSSsting类型属性属性名myString

变量size sizeof(NSString)

对齐指针类型的为log2(sizeof(NSString*))

类型 @encode(NSString*)

class_addIvar(class,变量名,变量size,对齐,类型)

//添加同名属性会失败

BOOL isd = class_addIvar(myClass, "_myString", sizeof(NSString *), log(sizeof(NSString *)), @encode(NSString *));

NSLog(@"属性是否添加成功 %d",isd);

特性相关编码

属性的特性字符串以 T@encode(type) 开头, 以 V实例变量名称结尾,中间以特性编码填充,通过property_getAttributes即可查看

特性编码具体含义

R readonly

C copy

& retain ARC strong

N nonatomic

G(name) getter=(name)

S(name) setter=(name)

D @dynamic

W weak

P 用于垃圾回收机制

//@T

objc_property_attribute_t type;

type.name = "T";

type.value = @encode(NSString *);

//copy

objc_property_attribute_t owership = {"C",""};

//nonatomic

objc_property_attribute_t oeership2 = {"N",""};

//V_属性名

objc_property_attribute_t var = {"V","_myString"};

//特性数组

objc_property_attribute_t attributes[] = {type,owership,oeership2,var};

//向类中添加名为myString的属性,属性的特性包含在attributes中

class_addProperty(myClass, "myString", attributes, 4);

unsigned int propertyCount;

objc_property_t * properties = class_copyPropertyList(myClass, &propertyCount);

for (int i = 0; i<propertyCount; i++) {

NSLog(@"属性的名称为 : %s",property_getName(properties[i]));

NSLog(@"属性的特性字符串为: %s",property_getAttributes(properties[i]));

}

//释放属性列表数组

free(properties);

//在应用中注册由objc_allocateClassPair创建的类

objc_registerClassPair(myClass);

id instance = [[myClass alloc] init];

[instance performSelector:@selector(mysubMethod1)];

[instance performSelector:@selector(method1)];

// 销毁一个类及相关联的类

// 不过需要注意的是，如果程序运行中还存在类或其子类的实例，则不能调用针对类调用该方法

//objc_disposeClassPair(myClass);

//关联对象

UIView *view = [[UIView alloc] initWithFrame:CGRectMake(100, 100, 100, 100)];

view.backgroundColor = [UIColor redColor];

[view setTapActionWithBlock:^{

NSLog(@"saAS");

}];

[self.view addSubview:view];

// SEL

// Objective-C在编译时，会依据每一个方法的名字、参数序列，生成一个唯一的整型标识(Int类型的地址)，这个标识就是SEL

// SEL只是一个指向方法的指针（准确的说，只是一个根据方法名hash化了的KEY值，能唯一代表一个方法

// 而对于字符串的比较仅仅需要比较他们的地址就可以了，可以说速度上无语伦比

// sel : 0x104dd7735

三种方法来获取SEL:

sel_registerName函数

Objective-C编译器提供的@selector()

NSSelectorFromString()方法

SEL sel1 = @selector(method1);

NSLog(@"sel : %p", sel1);

}

static void mysubMethod1(id self,SEL _cmd){

NSLog(@"这是添加的方法");

}

- (void)didReceiveMemoryWarning {

[super didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

@end

增加中，可先看demo