本篇英文名叫 OC Runtime In Action：CEO Cook Actually Used In Cooking，翻译过来的意思是开发人员实际开发的时候使用的 runtime 操作。进行积累整理。
隶属于我的第二个大系列 CWC ：Cooking With Cook，翻译过来的中文意思就是 作为一个长期热爱苹果的苹果开发者，陪着水果公司一起积累和成长。
首先简单罗列一下大部分的 runtime 的 API 方法
0. runtime方法概要
NSObject部分：
// 根据 instance 对象或者类名获得一个 class 对象
- (Class)class
+ (Class)class
// 判断当前 instance/class 对象的 isa 指向是不是 class/meta-class 对象或者它的子类类型
- (BOOL)isKindOfClass:(Class)cls
+ (BOOL)isKindOfClass:(Class)cls
// 判断当前 instance/class 对象的 isa 指向是不是 class/meta-class 对象类型
- (BOOL)isMemberOfClass:(Class)cls
+ (BOOL)isMemberOfClass:(Class)cls
// 判断对象是否可以接收特定消息
- (BOOL)respondsToSelector:(SEL)sel
+ (BOOL)respondsToSelector:(SEL)sel
// 判断对象是否实现了特定协议中定义的方法
- (BOOL)conformsToProtocol:(Protocol *)protocol
+ (BOOL)conformsToProtocol:(Protocol *)protocol
// 可以根据一个 SEL，得到该方法的 IMP
- (IMP)methodForSelector:(SEL)sel
+ (IMP)methodForSelector:(SEL)sel
Class 部分：
// 动态创建一对类和元类（参数：父类，类名，额外的内存空间）
Class objc_allocateClassPair(Class superclass, const char *name, size_t extraBytes)
// 注册一对类和元类（要在类注册之前添加成员变量）
void objc_registerClassPair(Class cls)
// 销毁一对类和元类
void objc_disposeClassPair(Class cls)
// 获取 isa 指向的 Class
Class object_getClass(id obj)
// 设置 isa 指向的 Class
Class object_setClass(id obj, Class cls)
// 判断一个 OC 对象是否为 Class
BOOL object_isClass(id obj)
// 判断一个 Class 是否为元类
BOOL class_isMetaClass(Class cls)
// 获取父类
Class class_getSuperclass(Class cls)
Property iVar 相关：
// 获取一个实例变量信息
Ivar class_getInstanceVariable(Class cls, const char *name)
// 拷贝实例变量列表（最后需要调用 free 释放）
Ivar *class_copyIvarList(Class cls, unsigned int *outCount)
// 设置和获取成员变量的值
void object_setIvar(id obj, Ivar ivar, id value)
id object_getIvar(id obj, Ivar ivar)
// 动态添加成员变量（已经注册的类是不能动态添加成员变量的）
BOOL class_addIvar(Class cls, const char * name, size_t size, uint8_t alignment, const char * types)
// 获取成员变量的相关信息
const char *ivar_getName(Ivar v)
const char *ivar_getTypeEncoding(Ivar v)
属性相关：
// 获取一个属性
objc_property_t class_getProperty(Class cls, const char *name)
// 拷贝属性列表（最后需要调用 free 释放）
objc_property_t *class_copyPropertyList(Class cls, unsigned int *outCount)
// 动态添加属性
BOOL class_addProperty(Class cls, const char *name, const objc_property_attribute_t *attributes, unsigned int attributeCount)
// 动态替换属性
void class_replaceProperty(Class cls, const char *name, const objc_property_attribute_t *attributes, unsigned int attributeCount)
// 获取属性的一些信息
const char *property_getName(objc_property_t property)
const char *property_getAttributes(objc_property_t property)
Method 相关：
// 获得一个实例方法、类方法
Method class_getInstanceMethod(Class cls, SEL name)
Method class_getClassMethod(Class cls, SEL name)
// 方法实现相关操作
IMP class_getMethodImplementation(Class cls, SEL name)
IMP method_setImplementation(Method m, IMP imp)
void method_exchangeImplementations(Method m1, Method m2)
// 拷贝方法列表（最后需要调用 free 释放）
Method *class_copyMethodList(Class cls, unsigned int *outCount)
// 动态添加方法
BOOL class_addMethod(Class cls, SEL name, IMP imp, const char *types)
// 动态替换方法
IMP class_replaceMethod(Class cls, SEL name, IMP imp, const char *types)
// 获取方法的相关信息（带有 copy 的需要调用 free 去释放）
SEL method_getName(Method m)
IMP method_getImplementation(Method m)
const char *method_getTypeEncoding(Method m)
unsigned int method_getNumberOfArguments(Method m)
char *method_copyReturnType(Method m)
char *method_copyArgumentType(Method m, unsigned int index)
// 选择器相关
const char *sel_getName(SEL sel)
SEL sel_registerName(const char *str)
// 用 block 作为方法实现
IMP imp_implementationWithBlock(id block)
id imp_getBlock(IMP anImp)
BOOL imp_removeBlock(IMP anImp)
关联对象相关：
// 添加关联对象
void objc_setAssociatedObject(id object, const void * key, id value, objc_AssociationPolicy policy)
// 获得关联对象
id objc_getAssociatedObject(id object, const void * key)
// 移除指定 object 的所有关联对象
void objc_removeAssociatedObjects(id object)
1. 接触 Runtime 的方式
正常开发的时候，我们通过三个渠道来接触到runtime
- OC 层面, eg：
@selector - Runtime API， eg:
objc-getclass()这些方法，msgSend()，setassosiciatedObject()等 - NSObject 相关的 API, eg:
2. 在lldb中打印 objc_class isa 的指向类
这点虽然不是调用runtime，但是涉及到了isa指针的相关知识。
直接通过位运算与上掩码来取类指针
image
这里与操作后面的值就是 ISAMASK，根据操作平台不同。
3. 通过 @encode 打印所有的type encodings
这个还是有用的，因为其实 method_t 里面满共就三四个值，一个name，一个imp实现指针，一个就是方法的 TypeEncodings
#pragma mark - 各种类型编码
void logAllTypeCodings() {
NSLog(@"char --> %s",@encode(char));
NSLog(@"int --> %s",@encode(int));
NSLog(@"short --> %s",@encode(short));
NSLog(@"long --> %s",@encode(long));
NSLog(@"long long --> %s",@encode(long long));
NSLog(@"unsigned char --> %s",@encode(unsigned char));
NSLog(@"unsigned int --> %s",@encode(unsigned int));
NSLog(@"unsigned short --> %s",@encode(unsigned short));
NSLog(@"unsigned long --> %s",@encode(unsigned long long));
NSLog(@"float --> %s",@encode(float));
NSLog(@"bool --> %s",@encode(bool));
NSLog(@"void --> %s",@encode(void));
NSLog(@"char * --> %s",@encode(char *));
NSLog(@"id --> %s",@encode(id));
NSLog(@"Class --> %s",@encode(Class));
NSLog(@"SEL --> %s",@encode(SEL));
int array[] = {1,2,3};
NSLog(@"int[] --> %s",@encode(typeof(array)));
typedef struct person{
char *name;
int age;
}Person;
NSLog(@"struct --> %s",@encode(Person));
typedef union union_type{
char *name;
int a;
}Union;
NSLog(@"union --> %s",@encode(Union));
int a = 2;
int *b = {&a};
NSLog(@"int[] --> %s",@encode(typeof(b)));
}
2020-11-01 15:21:03.434385+0800 001-类的属性与变量[34325:1798027] char --> c
2020-11-01 15:21:03.434742+0800 001-类的属性与变量[34325:1798027] int --> i
2020-11-01 15:21:03.434775+0800 001-类的属性与变量[34325:1798027] short --> s
2020-11-01 15:21:03.434796+0800 001-类的属性与变量[34325:1798027] long --> q
2020-11-01 15:21:03.434815+0800 001-类的属性与变量[34325:1798027] long long --> q
2020-11-01 15:21:03.434834+0800 001-类的属性与变量[34325:1798027] unsigned char --> C
2020-11-01 15:21:03.434855+0800 001-类的属性与变量[34325:1798027] unsigned int --> I
2020-11-01 15:21:03.434873+0800 001-类的属性与变量[34325:1798027] unsigned short --> S
2020-11-01 15:21:03.434891+0800 001-类的属性与变量[34325:1798027] unsigned long --> Q
2020-11-01 15:21:03.434910+0800 001-类的属性与变量[34325:1798027] float --> f
2020-11-01 15:21:03.434957+0800 001-类的属性与变量[34325:1798027] bool --> B
2020-11-01 15:21:03.434998+0800 001-类的属性与变量[34325:1798027] void --> v
2020-11-01 15:21:03.435051+0800 001-类的属性与变量[34325:1798027] char * --> *
2020-11-01 15:21:03.733132+0800 001-类的属性与变量[34325:1798027] id --> @
2020-11-01 15:21:03.733181+0800 001-类的属性与变量[34325:1798027] Class --> #
2020-11-01 15:21:03.733214+0800 001-类的属性与变量[34325:1798027] SEL --> :
2020-11-01 15:21:03.733242+0800 001-类的属性与变量[34325:1798027] int[] --> [3i]
2020-11-01 15:21:03.733270+0800 001-类的属性与变量[34325:1798027] struct --> {person=*I}
2020-11-01 15:21:03.733297+0800 001-类的属性与变量[34325:1798027] union --> (union_type=*i)
2020-11-01 15:21:03.733324+0800 001-类的属性与变量[34325:1798027] int[] --> ^i
4. 打印所有的类的属性
#import <objc/runtime.h>
#ifdef DEBUG
#define LGLog(format, ...) printf("%s\n", [[NSString stringWithFormat:format, ## __VA_ARGS__] UTF8String]);
#else
#define LGLog(format, ...);
#endif
void getObjc_copyIvar_copyProperies(Class pClass){
unsigned int count = 0;
Ivar *ivars = class_copyIvarList(pClass, &count);
for (unsigned int i=0; i < count; i++) {
Ivar const ivar = ivars[I];
//获取实例变量名
const char*cName = ivar_getName(ivar);
NSString *ivarName = [NSString stringWithUTF8String:cName];
LGLog(@"class_copyIvarList:%@",ivarName);
}
free(ivars);
unsigned int pCount = 0;
objc_property_t *properties = class_copyPropertyList(pClass, &pCount);
for (unsigned int i=0; i < pCount; i++) {
objc_property_t const property = properties[I];
//获取属性名
NSString *propertyName = [NSString stringWithUTF8String:property_getName(property)];
//获取属性值
LGLog(@"class_copyProperiesList:%@",propertyName);
}
free(properties);
}
5. 查找 方法
不像上一点那么通用，需要手动查是否包含该方法
#import <objc/runtime.h>
#ifdef DEBUG
#define getLog(format, ...) printf("%s\n", [[NSString stringWithFormat:format, ## __VA_ARGS__] UTF8String]);
#else
#define getLog(format, ...);
#endif
void getObjc_copyMethodList(Class pClass) {
unsigned int count = 0;
Method *methods = class_copyMethodList(pClass, &count);
for (unsigned int i=0; i < count; i++) {
Method const method = methods[I];
//获取方法名
NSString *key = NSStringFromSelector(method_getName(method));
getLog(@"Method, name: %@", key);
}
free(methods);
}
void getInstanceMethod_classToMetaclass(Class pClass) {
const char *className = class_getName(pClass);
Class metaClass = objc_getMetaClass(className);
Method method1 = class_getInstanceMethod(pClass, @selector(sayHello));
Method method2 = class_getInstanceMethod(metaClass, @selector(sayHello));
Method method3 = class_getInstanceMethod(pClass, @selector(sayHappy));
Method method4 = class_getInstanceMethod(metaClass, @selector(sayHappy));
getLog(@"%s - %p-%p-%p-%p",__func__,method1,method2,method3,method4);
}
void getClassMethod_classToMetaclass(Class pClass) {
const char *className = class_getName(pClass);
Class metaClass = objc_getMetaClass(className);
Method method1 = class_getClassMethod(pClass, @selector(sayHello));
Method method2 = class_getClassMethod(metaClass, @selector(sayHello));
Method method3 = class_getClassMethod(pClass, @selector(sayHappy));
// 元类 为什么有 sayHappy 类方法 0 1
//
Method method4 = class_getClassMethod(metaClass, @selector(sayHappy));
getLog(@"%s-%p-%p-%p-%p",__func__,method1,method2,method3,method4);
}
void getIMP_classToMetaclass(Class pClass) {
const char *className = class_getName(pClass);
Class metaClass = objc_getMetaClass(className);
// - (void)sayHello;
// + (void)sayHappy;
IMP imp1 = class_getMethodImplementation(pClass, @selector(sayHello));
IMP imp2 = class_getMethodImplementation(metaClass, @selector(sayHello));
IMP imp3 = class_getMethodImplementation(pClass, @selector(sayHappy));
IMP imp4 = class_getMethodImplementation(metaClass, @selector(sayHappy));
NSLog(@"%p-%p-%p-%p",imp1,imp2,imp3,imp4);
NSLog(@"%s",__func__);
}
6. print all properties
//- (void)printClassAllProperties:(Class)cls {
void printClassAllProperties(Class cls) {
unsigned int outCount = 0;
objc_property_t *properties = class_copyPropertyList(cls, &outCount);
NSMutableArray *propertiesAry = [NSMutableArray arrayWithCapacity:outCount];
for (int i = 0; i<outCount; i++) {
// objc property t 属性
objc_property_t property = properties[I];
// 获取属性名称 C字符串
const char *cName = property_getName(property);
// 转换成 OC 字符串
NSString *name = [NSString stringWithCString:cName encoding:NSUTF8StringEncoding];
[propertiesAry addObject:name];
NSLog(@"属性： %@", name);
}
}
另外这里有一个另外的函数，读取property 的 attribute，property_getAttributes(property)
打印出来会比如这种：T@"NSString",C,N,V_name
T:Type
C:copy
N:nonatomic
V:variable
7. 假装的本地 struct 逻辑结构
研究 bucket 的时候用到的。
因为除非是源码环境，否则业务环境工程我们拿不到源码的结构体，所以怎么办，只能自己写，假装我们有，在业务环境把源码环境骗过来:
typedef uint32_t mask_t; // x86_64 & arm64 asm are less efficient with 16-bits
struct lg_bucket_t {
SEL _sel;
IMP _imp;
};
struct lg_cache_t {
struct lg_bucket_t * _buckets;
mask_t _mask;
uint16_t _flags;
uint16_t _occupied;
};
struct lg_class_data_bits_t {
uintptr_t bits;
};
struct lg_objc_class {
Class ISA;
Class superclass;
struct lg_cache_t cache; // formerly cache pointer and vtable
struct lg_class_data_bits_t bits; // class_rw_t * plus custom rr/alloc flags
};
// 用法
int main(int argc, const char * argv[]) {
@autoreleasepool {
NSArray * ary = [[NSArray alloc] init];
struct lg_objc_class *lg_pClass = (__bridge struct lg_objc_class *)(ary);
NSLog(@"%hu - %u",lg_pClass->cache._occupied,lg_pClass->cache._mask);
for (mask_t i = 0; i<lg_pClass->cache._mask; i++) {
// 打印获取的 bucket
struct lg_bucket_t bucket = lg_pClass->cache._buckets[I];
NSLog(@"%@ - %p",NSStringFromSelector(bucket._sel),bucket._imp);
}
}
return 0;
}
8. instrumentObjcMessageSends
iOS, this works only on Simulator.
calling:
(void)instrumentObjcMessageSends(YES);
When I need to start logging all messages and then:
(void)instrumentObjcMessageSends(NO);
Don't forget to add #import <objc/runtime.h>.
When I don't need it anymore. The annoying thing is that the log is created under /tmp/msgSends- and this means that you have to open the terminal and use tail to see it in a readable way.
What is printed is something like this:
- CustomTableViewController UIViewController _parentModalViewController
- CustomTableViewController UIViewController isPerformingModalTransition
- CustomTableViewController UIViewController setInAnimatedVCTransition:
- CustomTableViewController UIViewController viewWillMoveToWindow:
- CustomTableViewController UIViewController isPerformingModalTransition
- CustomTableViewController UIViewController parentViewController
- CustomTableViewController UIViewController _popoverController
- CustomTableViewController UIViewController _didSelfOrAncestorBeginAppearanceTransition
- CustomTableViewController UIViewController parentViewController
- CustomTableViewController UIViewController __viewWillDisappear:
- CustomTableViewController UIViewController _setViewAppearState:isAnimating:
- CustomTableViewController UIViewController automaticallyForwardAppearanceAndRotationMethodsToChildViewControllers
这个方法的源码如下：
void instrumentObjcMessageSends(BOOL flag)
{
bool enable = flag;
// Shortcut NOP
if (objcMsgLogEnabled == enable)
return;
// If enabling, flush all method caches so we get some traces
if (enable)
_objc_flush_caches(Nil);
// Sync our log file
if (objcMsgLogFD != -1)
fsync (objcMsgLogFD);
objcMsgLogEnabled = enable;
}
9. 一些常见API的区别
iOS中内省的几个方法？
isMemberOfClass //对象是否是某个类型的对象
isKindOfClass //对象是否是某个类型或某个类型子类的对象
isSubclassOfClass //某个类对象是否是另一个类型的子类
isAncestorOfObject //某个类对象是否是另一个类型的父类
respondsToSelector //是否能响应某个方法
conformsToProtocol //是否遵循某个协议
10. 打印类和子类 + 打印所有方法
#pragma mark - 遍历方法-ivar-property
- (void)printClassAllMethod:(Class)cls{
unsigned int count = 0;
Method *methodList = class_copyMethodList(cls, &count);
for (int i = 0; i<count; i++) {
Method method = methodList[I];
SEL sel = method_getName(method);
IMP imp = class_getMethodImplementation(cls, sel);
NSLog(@"%@-%p",NSStringFromSelector(sel),imp);
}
free(methodList);
}
#pragma mark - 遍历类以及子类
- (void)printClasses:(Class)cls{
// 注册类的总数
int count = objc_getClassList(NULL, 0);
// 创建一个数组， 其中包含给定对象
NSMutableArray *mArray = [NSMutableArray arrayWithObject:cls];
// 获取所有已注册的类
Class* classes = (Class*)malloc(sizeof(Class)*count);
objc_getClassList(classes, count);
for (int i = 0; i<count; i++) {
if (cls == class_getSuperclass(classes[i])) {
[mArray addObject:classes[I]];
}
}
free(classes);
NSLog(@"classes = %@", mArray);
}
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