runtime
2019-04-17 本文已影响0人
英雄出少年
runtime介绍
- Objective-C是一门动态的编程语言，跟C、C++等语言有着很大的不同(编写代码 -> 编译链接 -> 运行)
- Objective-C的动态性是由Runtime API来支撑的
- Runtime API提供的接口基本都是C语言的，源码由C\C++\汇编语言编写
isa详解
- 在arm64架构之前，isa就是一个普通的指针，存储着Class、Meta-Class对象的内存地址
- 从arm64架构开始，对isa进行了优化，变成了一个共用体（union）结构，还使用位域来存储更多的信息
@interface TGPerson : NSObject
- (void)setTall:(BOOL)tall;
- (void)setRich:(BOOL)rich;
- (void)setHandsome:(BOOL)handsome;
- (void)setThin:(BOOL)thin;
- (BOOL)isTall;
- (BOOL)isRich;
- (BOOL)isHandsome;
- (BOOL)isThin;
@end
#import "TGPerson.h"
/**
把值存在不同的二进制位上，通过掩码来获取，共同体只开辟一份内存，减少内存的分配
*/
#define TGTallMask (1<<0)
#define TGRichMask (1<<1)
#define TGHandsomeMask (1<<2)
#define TGThinMask (1<<3)
@interface TGPerson ()
{
union {
char bits;
struct {
char tall : 1;
char rich : 1;
char handsome : 1;
char thin : 1;
}; //结构体只是增加可读性
} _tallRichHandsome;
}
@end
@implementation TGPerson
- (void)setTall:(BOOL)tall
{
if (tall) {
_tallRichHandsome.bits |= TGTallMask;
} else {
_tallRichHandsome.bits &= ~TGTallMask;// ~取反
}
}
- (BOOL)isTall
{
return !!(_tallRichHandsome.bits & TGTallMask);// !! 转成布尔类型
}
- (void)setRich:(BOOL)rich
{
if (rich) {
_tallRichHandsome.bits |= TGRichMask;
} else {
_tallRichHandsome.bits &= ~TGRichMask;
}
}
- (BOOL)isRich
{
return !!(_tallRichHandsome.bits & TGRichMask);
}
- (void)setHandsome:(BOOL)handsome
{
if (handsome) {
_tallRichHandsome.bits |= TGHandsomeMask;
} else {
_tallRichHandsome.bits &= ~TGHandsomeMask;
}
}
- (BOOL)isHandsome
{
return !!(_tallRichHandsome.bits & TGHandsomeMask);
}
- (void)setThin:(BOOL)thin
{
if (thin) {
_tallRichHandsome.bits |= TGThinMask;
} else {
_tallRichHandsome.bits &= ~TGThinMask;
}
}
- (BOOL)isThin
{
return !!(_tallRichHandsome.bits & TGThinMask);
}
@end
/********************* 写入、读取 **************************/
int main(int argc, const char * argv[]) {
@autoreleasepool {
TGPerson *person = [[TGPerson alloc] init];
person.thin = YES;
person.rich = YES;
person.handsome = NO;
NSLog(@"thin:%d rich:%d hansome:%d", person.isThin, person.isRich, person.isHandsome);
}
return 0;
}
isa内部结构.png
-
nonpointer
0，代表普通的指针，存储着Class、Meta-Class对象的内存地址
1，代表优化过，使用位域存储更多的信息 -
has_assoc
是否有设置过关联对象，如果没有，释放时会更快 -
has_cxx_dtor
是否有C++的析构函数（.cxx_destruct），如果没有，释放时会更快 -
shiftcls
存储着Class、Meta-Class对象的内存地址信息 -
magic
用于在调试时分辨对象是否未完成初始化 -
weakly_referenced
是否有被弱引用指向过，如果没有，释放时会更快 -
deallocating
对象是否正在释放 -
extra_rc
里面存储的值是引用计数器减1 -
has_sidetable_rc
引用计数器是否过大无法存储在isa中
如果为1，那么引用计数会存储在一个叫SideTable的类的属性中
oc对象销毁过程中会调用下面函数
/******************************************************
* objc_destructInstance
* Destroys an instance without freeing memory.
* Calls C++ destructors.
* Calls ARC ivar cleanup.
* Removes associative references.
* Returns `obj`. Does nothing if `obj` is nil.
*********************************************************/
void *objc_destructInstance(id obj)
{
if (obj) {
// Read all of the flags at once for performance.
bool cxx = obj->hasCxxDtor();
bool assoc = obj->hasAssociatedObjects();
// This order is important.
if (cxx) object_cxxDestruct(obj);
if (assoc) _object_remove_assocations(obj);
obj->clearDeallocating();
}
return obj;
}
#import "ViewController.h"
typedef enum {
// TGOptionsNone = 0, // 0b0000
TGOptionsOne = 1<<0, // 0b0001
TGOptionsTwo = 1<<1, // 0b0010
TGOptionsThree = 1<<2, // 0b0100
TGOptionsFour = 1<<3 // 0b1000
} TGOptions;
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
[self setOptions: TGOptionsOne | TGOptionsFour];
}
- (void)setOptions:(TGOptions)options
{
if (options & TGOptionsOne) {
NSLog(@"包含了TGOptionsOne");
}
if (options & TGOptionsTwo) {
NSLog(@"包含了TGOptionsTwo");
}
if (options & TGOptionsThree) {
NSLog(@"包含了TGOptionsThree");
}
if (options & TGOptionsFour) {
NSLog(@"包含了TGOptionsFour");
}
}
class结构
class内部结构
class_ro_t
class_ro_t里面的baseMethodList、baseProtocols、ivars、baseProperties是一维数组，是只读的，包含了类的初始内容,一开始就有
class_ro_t.png
class_rw_t
class_rw_t里面的methods、properties、protocols是二维数组，是可读可写的，包含了类的初始内容、分类的内容,一开始没有
class_rw_t
method_t
- method_t是对方法\函数的封装
struct method_t {
SEL name; //函数名
const char *types; //编码(返回值类型、参数类型)
MethodListIMP imp;//指向函数的指针(函数地址)
}
-
IMP代表函数的具体实现
IMP.png
- SEL代表方法\函数名，一般叫做选择器，底层结构跟char *类似
- 可以通过@selector()和sel_registerName()获得
- 可以通过sel_getName()和NSStringFromSelector()转成字符串
-
不同类中相同名字的方法，所对应的方法选择器是相同的
SEL.png
types包含了函数返回值、参数编码的字符串
types
methods
@interface TGPerson : NSObject
// "i24@0:8i16f20"
// 0id 8SEL 16int 20float == 24
/**
* i表示返回值类型 24表示 参数总共占多少字节数
*@表示第一个参数是id类型 从第0个字节开始
*：表示参数是SEL 从第8个字节开始
* i表示参数是int类型 从20字节开始
*f表示参数是 float类型 从20字节开始
*/
- (int)test:(int)age height:(float)height;
@end
encoding.png
type-encoding.png
static Class realizeClass(Class cls)
{
runtimeLock.assertLocked();
const class_ro_t *ro;
class_rw_t *rw;
Class supercls;
Class metacls;
bool isMeta;
if (!cls) return nil;
if (cls->isRealized()) return cls;
assert(cls == remapClass(cls));
// fixme verify class is not in an un-dlopened part of the shared cache?
ro = (const class_ro_t *)cls->data();//ro一开始就有
if (ro->flags & RO_FUTURE) {
// This was a future class. rw data is already allocated.
rw = cls->data();
ro = cls->data()->ro;
cls->changeInfo(RW_REALIZED|RW_REALIZING, RW_FUTURE);
} else {
// Normal class. Allocate writeable class data.
rw = (class_rw_t *)calloc(sizeof(class_rw_t), 1);//rw一开始没有
rw->ro = ro;
rw->flags = RW_REALIZED|RW_REALIZING;
cls->setData(rw);
}
// Realize superclass and metaclass, if they aren't already.
// This needs to be done after RW_REALIZED is set above, for root classes.
// This needs to be done after class index is chosen, for root metaclasses.
supercls = realizeClass(remapClass(cls->superclass));
metacls = realizeClass(remapClass(cls->ISA()));
// Update superclass and metaclass in case of remapping
cls->superclass = supercls;
cls->initClassIsa(metacls);
// Reconcile instance variable offsets / layout.
// This may reallocate class_ro_t, updating our ro variable.
if (supercls && !isMeta) reconcileInstanceVariables(cls, supercls, ro);
// Set fastInstanceSize if it wasn't set already.
cls->setInstanceSize(ro->instanceSize);
// Copy some flags from ro to rw
if (ro->flags & RO_HAS_CXX_STRUCTORS) {
cls->setHasCxxDtor();
if (! (ro->flags & RO_HAS_CXX_DTOR_ONLY)) {
cls->setHasCxxCtor();
}
}
// Connect this class to its superclass's subclass lists
if (supercls) {
addSubclass(supercls, cls);
} else {
addRootClass(cls);
}
methodizeClass(cls);
return cls;
}
方法缓存
Class内部结构中有个方法缓存（cache_t），用散列表（哈希表）来缓存曾经调用过的方法，可以提高方法的查找速度
缓存查找
内部结构
缓存查找
objc-cache.mm
bucket_t * cache_t::find(cache_key_t k, id receiver)
bucket_t * cache_t::find(cache_key_t k, id receiver)
{
assert(k != 0);
bucket_t *b = buckets();
mask_t m = mask();
//k 是selector m是mask
mask_t begin = cache_hash(k, m);
//i 索引
mask_t i = begin;
do {
if (b[i].key() == 0 || b[i].key() == k) { //找到就直接返回地址
return &b[I];
}
} while ((i = cache_next(i, m)) != begin);//找不到就遍历前面一个
// hack
Class cls = (Class)((uintptr_t)this - offsetof(objc_class, cache));
cache_t::bad_cache(receiver, (SEL)k, cls);
}
//内存不够就会重新设置mask 并清除缓存
void cache_t::expand()
{
cacheUpdateLock.assertLocked();
uint32_t oldCapacity = capacity();
//存储空间变为原来的两倍
uint32_t newCapacity = oldCapacity ? oldCapacity*2 : INIT_CACHE_SIZE;
if ((uint32_t)(mask_t)newCapacity != newCapacity) {
// mask overflow - can't grow further
// fixme this wastes one bit of mask
newCapacity = oldCapacity;
}
reallocate(oldCapacity, newCapacity);
}
方法缓存
散列表
类的cache里 ，cache里有个散列表数组 ，selector作为key & mask 获取到索引
算列表
int main(int argc, const char * argv[]) {
@autoreleasepool {
MJGoodStudent *goodStudent = [[MJGoodStudent alloc] init];
mj_objc_class *goodStudentClass = (__bridge mj_objc_class *)[MJGoodStudent class];
[goodStudent goodStudentTest];
[goodStudent studentTest];
[goodStudent personTest];
[goodStudent goodStudentTest];
[goodStudent studentTest];
cache_t cache = goodStudentClass->cache;
// NSLog(@"%s %p", @selector(personTest), cache.imp(@selector(personTest)));
// NSLog(@"%s %p", @selector(studentTest), cache.imp(@selector(studentTest)));
// NSLog(@"%s %p", @selector(goodStudentTest), cache.imp(@selector(goodStudentTest)));
//获取buckets散列表
bucket_t *buckets = cache._buckets;
//获取bucket
bucket_t bucket = buckets[(long long)@selector(studentTest) & cache._mask];
NSLog(@"%s %p", bucket._key, bucket._imp);
for (int i = 0; i <= cache._mask; i++) {
bucket_t bucket = buckets[I];
if(bucket._key == 0) continue;
NSLog(@"%lu %p", bucket._key, bucket._imp);
}
}
return 0;
}
打印缓存里的方法
objc_msgSend
- OC中的方法调用，其实都是转换为objc_msgSend函数的调用
- objc_msgSend的执行流程可以分为3大阶段
-
消息发送 (利用objc_msgSend尝试找到方法进行调用)
消息发送阶段
-
动态方法解析(找不到方法,进入到动态方法解析阶段 )
-
@implementation TGPerson
//Method类型的底层实现
struct method_t {
SEL sel;
char *types;
IMP imp;
};
void c_other(id self, SEL _cmd)
{
NSLog(@"c_other - %@ - %@", self, NSStringFromSelector(_cmd));
}
- (void)other
{
NSLog(@"%s", __func__);
}
+ (BOOL)resolveInstanceMethod:(SEL)sel
{
if (sel == @selector(test)) {
//第一种方式
// 获取其他方法
struct method_t *method = (struct method_t *)class_getInstanceMethod(self, @selector(other));
// 动态添加test方法的实现
class_addMethod(self, sel, method->imp, method->types);
//第二种方式
/**
Method method = class_getInstanceMethod(self, @selector(other));
class_addMethod(self, sel,
method_getImplementation(method),
method_getTypeEncoding(method));
*/
//第三种方式
// class_addMethod(self, sel, (IMP)c_other, "v16@0:8");
// 返回YES代表有动态添加方法
return YES;
}
return [super resolveInstanceMethod:sel];
}
@end
int main(int argc, const char * argv[]) {
@autoreleasepool {
TGPerson *person = [[TGPerson alloc] init];
[person test];
// [TGPerson test];
}
return 0;
}
动态方法解析
@dynamic是告诉编译器不用自动生成getter和setter的实现，由用户自己实现
@synthesize表示如果属性没有手动实现setter和getter方法，编译器会自动加上这两个方法
-
消息转发(方法解析阶段 没有做任何操作，进入到消息转发阶段)
消息转发
int main(int argc, const char * argv[]) {
@autoreleasepool {
TGPerson *person = [[TGPerson alloc] init];
[person test:15];
}
return 0;
}
@implementation TGPerson
// 方法签名：返回值类型、参数类型
- (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector
{
if (aSelector == @selector(test)) {
// return [NSMethodSignature signatureWithObjCTypes:"v16@0:8"];
return [NSMethodSignature signatureWithObjCTypes:"i@:I"];
}
return [super methodSignatureForSelector:aSelector];
}
// NSInvocation封装了一个方法调用，包括：方法调用者、方法名、方法参数
// anInvocation.target 方法调用者
// anInvocation.selector 方法名
// [anInvocation getArgument:NULL atIndex:0]
- (void)forwardInvocation:(NSInvocation *)anInvocation
{
/**
参数顺序：receiver、selector、other arguments
int age;
[anInvocation getArgument:&age atIndex:2];
NSLog(@"%d", age + 10);
*/
// anInvocation.target == [[MJCat alloc] init]
// anInvocation.selector == test:
// anInvocation的参数：15
// [[[TGCat alloc] init] test:15]
[anInvocation invokeWithTarget:[[TGCat alloc] init]];
}
@end
源码阅读
-
objc-msg-arm64.s
- ENTRY _objc_msgSend
- b.le LNilOrTagged
- CacheLookup NORMAL
- .macro CacheLookup
- .macro CheckMiss
- STATIC_ENTRY __objc_msgSend_uncached
- .macro MethodTableLookup
- __class_lookupMethodAndLoadCache3
-
objc-runtime-new.mm
- _class_lookupMethodAndLoadCache3
- lookUpImpOrForward
- getMethodNoSuper_nolock、search_method_list、log_and_fill_cache
- cache_getImp、log_and_fill_cache、 getMethodNoSuper_nolock、log_and_fill_cache
- _class_resolveInstanceMethod
- _objc_msgForward_impcache
-
objc-msg-arm64.s
- STATIC_ENTRY __objc_msgForward_impcache
- ENTRY __objc_msgForward
-
Core Foundation
- forwarding（不开源）
super 面试题
@implementation MJStudent
/*
including the instance of the class that is to receive the message and the superclass at which to start searching for the method implementation
[super message]的底层实现
1.消息接收者仍然是子类对象
2.从父类开始查找方法的实现
*/
//super调用，底层会转换为objc_msgSendSuper2函数的调用，接收2个参数
struct objc_super2 { //底层实现
id receiver; // 消息接收者
Class current_class; // 当前类类
};
struct objc_super { //重写c++实现
__unsafe_unretained _Nonnull id receiver; // 消息接收者
__unsafe_unretained _Nonnull Class super_class; // 消息接收者的父类
};
- (void)run
{
// super调用的receiver仍然是MJStudent对象
[super run];
// struct objc_super arg = {self, [MJPerson class]};
// objc_msgSendSuper(arg, @selector(run));
}
- (instancetype)init
{
if (self = [super init]) {
NSLog(@"[self class] = %@", [self class]); // MJStudent
NSLog(@"[self superclass] = %@", [self superclass]); // MJPerson
NSLog(@"--------------------------------");
// objc_msgSendSuper({self, [MJPerson class]}, @selector(class));
NSLog(@"[super class] = %@", [super class]); // MJStudent
NSLog(@"[super superclass] = %@", [super superclass]); // MJPerson
}
return self;
}
@end
//@implementation NSObject
//
//- (Class)class
//{
// return object_getClass(self);
//}
//
//- (Class)superclass
//{
// return class_getSuperclass(object_getClass(self));
//}
//
//@end
isMemberOfClass、isKindOfClass
- isMemberOfClass底层实现
//判断类型是否相等
+ (BOOL)isMemberOfClass:(Class)cls {
return object_getClass((id)self) == cls;
}
- (BOOL)isMemberOfClass:(Class)cls {
return [self class] == cls;
}
- isKindOfClass 底层实现
//左边类型是否等于右边类型或是右边类型的子类
- (BOOL)isKindOfClass:(Class)cls {
for (Class tcls = [self class]; tcls; tcls = tcls->superclass) {
if (tcls == cls) return YES;
}
return NO;
}
+ (BOOL)isKindOfClass:(Class)cls {
for (Class tcls = object_getClass((id)self); tcls; tcls = tcls->superclass) {
if (tcls == cls) return YES;
}
return NO;
}
int main(int argc, const char * argv[]) {
@autoreleasepool {
// NSLog(@"%d", [[NSObject class] isKindOfClass:[NSObject class]]);
// NSLog(@"%d", [[NSObject class] isMemberOfClass:[NSObject class]]);
// NSLog(@"%d", [[MJPerson class] isKindOfClass:[MJPerson class]]);
// NSLog(@"%d", [[MJPerson class] isMemberOfClass:[MJPerson class]]);
// 这句代码的方法调用者不管是哪个类（只要是NSObject体系下的），都返回YES
//object_getClass
NSLog(@"%d", [NSObject isKindOfClass:[NSObject class]]); // 1
NSLog(@"%d", [NSObject isMemberOfClass:[NSObject class]]); // 0
NSLog(@"%d", [MJPerson isKindOfClass:[MJPerson class]]); // 0
NSLog(@"%d", [MJPerson isMemberOfClass:[MJPerson class]]); // 0
// id person = [[MJPerson alloc] init];
// NSLog(@"%d", [person isMemberOfClass:[MJPerson class]]);
// NSLog(@"%d", [person isMemberOfClass:[NSObject class]]);
// NSLog(@"%d", [person isKindOfClass:[MJPerson class]]);
// NSLog(@"%d", [person isKindOfClass:[NSObject class]]);
// NSLog(@"%d", [MJPerson isMemberOfClass:object_getClass([MJPerson class])]);
// NSLog(@"%d", [MJPerson isKindOfClass:object_getClass([NSObject class])]);
// NSLog(@"%d", [MJPerson isKindOfClass:[NSObject class]]);
}
return 0;
}
// 局部变量分配在栈空间
// 栈空间分配，从高地址到低地址
void test()
{
long long a = 4; // 0x7ffee638bff8
long long b = 5; // 0x7ffee638bff0
long long c = 6; // 0x7ffee638bfe8
long long d = 7; // 0x7ffee638bfe0
NSLog(@"%p %p %p %p", &a, &b, &c, &d);
}
int main(int argc, char * argv[]) {
@autoreleasepool {
// test();
return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
}
}
@implementation ViewController
/*
1.print为什么能够调用成功？
2.为什么self.name变成了ViewController等其他内容
*/
- (void)viewDidLoad {
[super viewDidLoad];
// struct abc = { //隐藏的结构体
// self,
// [ViewController class]
// };
// objc_msgSendSuper2(abc, sel_registerName("viewDidLoad"));
// NSObject *obj2 = [[NSObject alloc] init];
//
// NSString *test = @"123";
id cls = [MJPerson class];
void *obj = &cls;
[(__bridge id)obj print];
// long long *p = (long long *)obj;
// NSLog(@"%p %p", *(p+2), [ViewController class]);
// struct MJPerson_IMPL
// {
// Class isa;
// NSString *_name;
// };
}
@end
画图分析
画图分析
画图分析
runtime的应用
- 类
//动态创建一个类（参数：父类，类名，额外的内存空间）
Class objc_allocateClassPair(Class superclass, const char *name, size_t extraBytes)
//注册一个类（要在类注册之前添加成员变量）
void objc_registerClassPair(Class cls)
//销毁一个类
void objc_disposeClassPair(Class cls)
//获取isa指向的Class
Class object_getClass(id obj)
MJPerson *person = [[MJPerson alloc] init];
object_getClass(person) //获取类对象
object_getClass([MJPerson class]) //获取元类对象
//设置isa指向的Class
Class object_setClass(id obj, Class cls)
object_setClass(person, [MJCar class]);
[person run]; //调用 MJCar的run方法
//判断一个OC对象是否为Class
BOOL object_isClass(id obj)
NSLog(@"%d %d %d",
object_isClass(person),
object_isClass([MJPerson class]),
object_isClass(object_getClass([MJPerson class]))
);
//判断一个Class是否为元类
BOOL class_isMetaClass(Class cls)
//获取父类
Class class_getSuperclass(Class cls)
void testClass()
{
// 创建类
Class newClass = objc_allocateClassPair([NSObject class], "MJDog", 0);
class_addIvar(newClass, "_age", 4, 1, @encode(int));
class_addIvar(newClass, "_weight", 4, 1, @encode(int));
class_addMethod(newClass, @selector(run), (IMP)run, "v@:");
// 注册类
objc_registerClassPair(newClass);
MJPerson *person = [[MJPerson alloc] init];
object_setClass(person, newClass);
[person run];
id dog = [[newClass alloc] init];
[dog setValue:@10 forKey:@"_age"];
[dog setValue:@20 forKey:@"_weight"];
[dog run];
NSLog(@"%@ %@", [dog valueForKey:@"_age"], [dog valueForKey:@"_weight"]);
// 在不需要这个类时释放
objc_disposeClassPair(newClass);
}
- 成员变量
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)
void testIvars()
{
// 获取成员变量信息
// Ivar ageIvar = class_getInstanceVariable([MJPerson class], "_age");
// NSLog(@"%s %s", ivar_getName(ageIvar), ivar_getTypeEncoding(ageIvar));
// 设置和获取成员变量的值
// Ivar nameIvar = class_getInstanceVariable([MJPerson class], "_name");
//
// MJPerson *person = [[MJPerson alloc] init];
// object_setIvar(person, nameIvar, @"123");
// object_setIvar(person, ageIvar, (__bridge id)(void *)10);
// NSLog(@"%@ %d", person.name, person.age);
// 成员变量的数量
unsigned int count;
Ivar *ivars = class_copyIvarList([MJPerson class], &count);
for (int i = 0; i < count; i++) {
// 取出i位置的成员变量
Ivar ivar = ivars[I];
NSLog(@"%s %s", ivar_getName(ivar), ivar_getTypeEncoding(ivar));
}
free(ivars);
}
Ivar *ivars = class_copyIvarList([UITextField class], &count);
for (int i = 0; i < count; i++) {
// 取出i位置的成员变量
Ivar ivar = ivars[i];
NSLog(@"%s %s", ivar_getName(ivar), ivar_getTypeEncoding(ivar));
}
free(ivars);
- 属性
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)
- 方法
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)
void myrun()
{
NSLog(@"---myrun");
}
void test()
{
MJPerson *person = [[MJPerson alloc] init];
// class_replaceMethod([MJPerson class], @selector(run), (IMP)myrun, "v");
class_replaceMethod([MJPerson class], @selector(run), imp_implementationWithBlock(^{
NSLog(@"123123");
}), "v");
[person run];
}
@implementation UIControl (Extension)
+ (void)load
{
// hook：钩子函数
Method method1 = class_getInstanceMethod(self, @selector(sendAction:to:forEvent:));
Method method2 = class_getInstanceMethod(self, @selector(mj_sendAction:to:forEvent:));
method_exchangeImplementations(method1, method2);
}
- (void)mj_sendAction:(SEL)action to:(id)target forEvent:(UIEvent *)event
{
NSLog(@"%@-%@-%@", self, target, NSStringFromSelector(action));
// 调用系统原来的实现
[self mj_sendAction:action to:target forEvent:event];
// [target performSelector:action];
// if ([self isKindOfClass:[UIButton class]]) {
// // 拦截了所有按钮的事件
//
// }
}
@end
@implementation NSMutableArray (Extension)
+ (void)load
{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
// 类簇：NSString、NSArray、NSDictionary，真实类型是其他类型
Class cls = NSClassFromString(@"__NSArrayM");
Method method1 = class_getInstanceMethod(cls, @selector(insertObject:atIndex:));
Method method2 = class_getInstanceMethod(cls, @selector(mj_insertObject:atIndex:));
method_exchangeImplementations(method1, method2);
});
}
- (void)mj_insertObject:(id)anObject atIndex:(NSUInteger)index
{
if (anObject == nil) return;
[self mj_insertObject:anObject atIndex:index];
}
@end
@implementation NSMutableDictionary (Extension)
+ (void)load
{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
Class cls = NSClassFromString(@"__NSDictionaryM");
Method method1 = class_getInstanceMethod(cls, @selector(setObject:forKeyedSubscript:));
Method method2 = class_getInstanceMethod(cls, @selector(mj_setObject:forKeyedSubscript:));
method_exchangeImplementations(method1, method2);
Class cls2 = NSClassFromString(@"__NSDictionaryI");
Method method3 = class_getInstanceMethod(cls2, @selector(objectForKeyedSubscript:));
Method method4 = class_getInstanceMethod(cls2, @selector(mj_objectForKeyedSubscript:));
method_exchangeImplementations(method3, method4);
});
}
- (void)mj_setObject:(id)obj forKeyedSubscript:(id<NSCopying>)key
{
if (!key) return;
[self mj_setObject:obj forKeyedSubscript:key];
}
- (id)mj_objectForKeyedSubscript:(id)key
{
if (!key) return nil;
return [self mj_objectForKeyedSubscript:key];
}
@end
- 字典转模型
@implementation NSObject (Json)
+ (instancetype)mj_objectWithJson:(NSDictionary *)json
{
id obj = [[self alloc] init];
unsigned int count;
Ivar *ivars = class_copyIvarList(self, &count);
for (int i = 0; i < count; i++) {
// 取出i位置的成员变量
Ivar ivar = ivars[i];
NSMutableString *name = [NSMutableString stringWithUTF8String:ivar_getName(ivar)];
[name deleteCharactersInRange:NSMakeRange(0, 1)];
// 设值
id value = json[name];
[obj setValue:value forKey:name];
}
free(ivars);
return obj;
}
int main(int argc, const char * argv[]) {
@autoreleasepool {
// 字典转模型
NSDictionary *json = @{
@"id" : @20,
@"age" : @20,
@"weight" : @60,
@"name" : @"Jack"
};
MJPerson *person = [MJPerson mj_objectWithJson:json];
NSLog(@"123");
}
return 0;
}
