分类
在main中添加LGPerson分类
@interface LGPerson (LGA)
@property(nonatomic,copy)NSString *cate_name;
@property(nonatomic,assign)int cate_age;
+(void)cate_sayClassMethod;
-(void)cate_MethodA;
-(void)cate_MethodC;
-(void)cate_MethodB;
@end
@implementation LGPerson (LGA)
+(void)cate_sayClassMethod{
}
-(void)cate_MethodA{
}
-(void)cate_MethodC{
}
-(void)cate_MethodB{
}
通过clang -x objective-c -rewrite-objc -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk main.m将mian编译成c++文件
struct _category_t {
const char *name;
struct _class_t *cls;
const struct _method_list_t *instance_methods;
const struct _method_list_t *class_methods;
const struct _protocol_list_t *protocols;
const struct _prop_list_t *properties;
};
extern "C" __declspec(dllimport) struct objc_cache _objc_empty_cache;
#pragma warning(disable:4273)
static struct /*_method_list_t*/ {
unsigned int entsize; // sizeof(struct _objc_method)
unsigned int method_count;
struct _objc_method method_list[3];
} _OBJC_$_CATEGORY_INSTANCE_METHODS_LGPerson_$_LGA __attribute__ ((used, section ("__DATA,__objc_const"))) = {
sizeof(_objc_method),
3,
{{(struct objc_selector *)"cate_MethodA", "v16@0:8", (void *)_I_LGPerson_LGA_cate_MethodA},
{(struct objc_selector *)"cate_MethodC", "v16@0:8", (void *)_I_LGPerson_LGA_cate_MethodC},
{(struct objc_selector *)"cate_MethodB", "v16@0:8", (void *)_I_LGPerson_LGA_cate_MethodB}}
};
static struct /*_method_list_t*/ {
unsigned int entsize; // sizeof(struct _objc_method)
unsigned int method_count;
struct _objc_method method_list[1];
} _OBJC_$_CATEGORY_CLASS_METHODS_LGPerson_$_LGA __attribute__ ((used, section ("__DATA,__objc_const"))) = {
sizeof(_objc_method),
1,
{{(struct objc_selector *)"cate_sayClassMethod", "v16@0:8", (void *)_C_LGPerson_LGA_cate_sayClassMethod}}
};
static struct /*_prop_list_t*/ {
unsigned int entsize; // sizeof(struct _prop_t)
unsigned int count_of_properties;
struct _prop_t prop_list[2];
} _OBJC_$_PROP_LIST_LGPerson_$_LGA __attribute__ ((used, section ("__DATA,__objc_const"))) = {
sizeof(_prop_t),
2,
{{"cate_name","T@\"NSString\",C,N"},
{"cate_age","Ti,N"}}
};
我们可以看到没有getter setter {{(struct objc_selector *)"cate_MethodA", "v16@0:8", (void *)_I_LGPerson_LGA_cate_MethodA}与method_t一致
struct method_t {
SEL name;
const char *types;
MethodListIMP imp;
struct SortBySELAddress :
public std::binary_function<const method_t&,
const method_t&, bool>
{
bool operator() (const method_t& lhs,
const method_t& rhs)
{ return lhs.name < rhs.name; }
};
};
我们也可以看官方文档shift+command+0搜索Category可以看到
typedef struct objc_category *Category;
struct objc_category {
char * _Nonnull category_name OBJC2_UNAVAILABLE;
char * _Nonnull class_name OBJC2_UNAVAILABLE;
struct objc_method_list * _Nullable instance_methods OBJC2_UNAVAILABLE;
struct objc_method_list * _Nullable class_methods OBJC2_UNAVAILABLE;
struct objc_protocol_list * _Nullable protocols OBJC2_UNAVAILABLE;
} OBJC2_UNAVAILABLE;
我们在上面的methodizeClass方法中看到处理分类的方法objc::unattachedCategories.attachToClass
void attachToClass(Class cls, Class previously, int flags)
{
runtimeLock.assertLocked();
ASSERT((flags & ATTACH_CLASS) ||
(flags & ATTACH_METACLASS) ||
(flags & ATTACH_CLASS_AND_METACLASS));
auto &map = get();
auto it = map.find(previously);//分类一个一个查找处理
if (it != map.end()) {
category_list &list = it->second;
if (flags & ATTACH_CLASS_AND_METACLASS) {
int otherFlags = flags & ~ATTACH_CLASS_AND_METACLASS;
attachCategories(cls, list.array(), list.count(), otherFlags | ATTACH_CLASS);
attachCategories(cls->ISA(), list.array(), list.count(), otherFlags | ATTACH_METACLASS);
} else {
attachCategories(cls, list.array(), list.count(), flags);
}
map.erase(it);
}
}
//将方法列表、属性和协议从类别附加到类中。
//假设所有cats中的类别都已加载并按加载顺序排序，
//先有最古老的类别。
static void
attachCategories(Class cls, const locstamped_category_t *cats_list, uint32_t cats_count,
int flags)
{
if (slowpath(PrintReplacedMethods)) {
printReplacements(cls, cats_list, cats_count);
}
if (slowpath(PrintConnecting)) {
_objc_inform("CLASS: attaching %d categories to%s class '%s'%s",
cats_count, (flags & ATTACH_EXISTING) ? " existing" : "",
cls->nameForLogging(), (flags & ATTACH_METACLASS) ? " (meta)" : "");
}
/*
* Only a few classes have more than 64 categories during launch.
* This uses a little stack, and avoids malloc.
*
* Categories must be added in the proper order, which is back
* to front. To do that with the chunking, we iterate cats_list
* from front to back, build up the local buffers backwards,
* and call attachLists on the chunks. attachLists prepends the
* lists, so the final result is in the expected order.
*/
constexpr uint32_t ATTACH_BUFSIZ = 64;
method_list_t *mlists[ATTACH_BUFSIZ];
property_list_t *proplists[ATTACH_BUFSIZ];
protocol_list_t *protolists[ATTACH_BUFSIZ];
uint32_t mcount = 0;
uint32_t propcount = 0;
uint32_t protocount = 0;
bool fromBundle = NO;
bool isMeta = (flags & ATTACH_METACLASS);
auto rwe = cls->data()->extAllocIfNeeded();//rwe 初始化 本类被添加了
for (uint32_t i = 0; i < cats_count; i++) {
auto& entry = cats_list[i];
method_list_t *mlist = entry.cat->methodsForMeta(isMeta);
if (mlist) {
if (mcount == ATTACH_BUFSIZ) {
prepareMethodLists(cls, mlists, mcount, NO, fromBundle);
rwe->methods.attachLists(mlists, mcount);
mcount = 0;
}
mlists[ATTACH_BUFSIZ - ++mcount] = mlist;//倒序插入
fromBundle |= entry.hi->isBundle();
}
...
}
if (mcount > 0) {
prepareMethodLists(cls, mlists + ATTACH_BUFSIZ - mcount, mcount, NO, fromBundle);
rwe->methods.attachLists(mlists + ATTACH_BUFSIZ - mcount, mcount);
if (flags & ATTACH_EXISTING) flushCaches(cls);
}
rwe->properties.attachLists(proplists + ATTACH_BUFSIZ - propcount, propcount);//内存平移，指针地址
rwe->protocols.attachLists(protolists + ATTACH_BUFSIZ - protocount, protocount);
}
void attachLists(List* const * addedLists, uint32_t addedCount) {
if (addedCount == 0) return;
if (hasArray()) {
// many lists -> many lists
uint32_t oldCount = array()->count;
uint32_t newCount = oldCount + addedCount;
setArray((array_t *)realloc(array(), array_t::byteSize(newCount)));
array()->count = newCount;
memmove(array()->lists + addedCount, array()->lists,
oldCount * sizeof(array()->lists[0]));
memcpy(array()->lists, addedLists,
addedCount * sizeof(array()->lists[0]));
}
else if (!list && addedCount == 1) {
// 0 lists -> 1 list
//一维
list = addedLists[0];
}
else {
// 1 list -> many lists
List* oldList = list;
uint32_t oldCount = oldList ? 1 : 0;
uint32_t newCount = oldCount + addedCount;//算出容量
setArray((array_t *)malloc(array_t::byteSize(newCount)));//新建数组
array()->count = newCount;
if (oldList) array()->lists[addedCount] = oldList;//将list向后移，为新添加腾出位子
memcpy(array()->lists, addedLists,
addedCount * sizeof(array()->lists[0]));//新添加的插入前面，所以同名的会先调用分类方法
}
}
这个时候我们可以全局搜索和通过lldb打印bt知道attachCategories流程
attachCategories流程.png
我们这里有两个分类
@interface LGPerson (LGA)
- (void)cateA_1;
- (void)cateA_2;
- (void)cateA_3;
@end
@implementation LGPerson (LGA)
+ (void)load{
}
- (void)kc_instanceMethod1{
NSLog(@"%s",__func__);
}
- (void)cateA_2{
NSLog(@"%s",__func__);
}
- (void)cateA_1{
NSLog(@"%s",__func__);
}
- (void)cateA_3{
NSLog(@"%s",__func__);
}
@end
@interface LGPerson (LGB)
- (void)cateB_1;
- (void)cateB_2;
- (void)cateB_3;
@end
@implementation LGPerson (LGB)
+ (void)load{
}
- (void)kc_instanceMethod1{
NSLog(@"%s",__func__);
}
- (void)cateB_2{
NSLog(@"%s",__func__);
}
- (void)cateB_1{
NSLog(@"%s",__func__);
}
- (void)cateB_3{
NSLog(@"%s",__func__);
}
我们在两个分类中都实现了load方法，所以我们一开始就加载了分类，现在我们调试下不实现load,一个分类加载load，会使其他分类提前加载
1: 主类 load 分类 load 全部 - load_image 加载到数据
2: 懒加载类 + ⾮懒加载分类 : 迫使类成为⾮懒加载类样式来提前加载数据
3: 懒加载类 + 懒加载分类 : 消息第⼀次调⽤ (加载数据)
4: ⾮懒加载类 + 懒加载分类 : read_image 就加载数据
1，2属于运行期处理的；3，4属于编译期处理的
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