iOS YYModel 源码 解析 （YYClassInfo.h）

YYEncodingType

/**
 Type encoding's type. */ typedef NS_OPTIONS(NSUInteger, YYEncodingType) { YYEncodingTypeMask = 0xFF, ///< mask of type value YYEncodingTypeUnknown = 0, ///< unknown YYEncodingTypeVoid = 1, ///< void YYEncodingTypeBool = 2, ///< bool YYEncodingTypeInt8 = 3, ///< char / BOOL YYEncodingTypeUInt8 = 4, ///< unsigned char YYEncodingTypeInt16 = 5, ///< short YYEncodingTypeUInt16 = 6, ///< unsigned short YYEncodingTypeInt32 = 7, ///< int YYEncodingTypeUInt32 = 8, ///< unsigned int YYEncodingTypeInt64 = 9, ///< long long YYEncodingTypeUInt64 = 10, ///< unsigned long long YYEncodingTypeFloat = 11, ///< float YYEncodingTypeDouble = 12, ///< double YYEncodingTypeLongDouble = 13, ///< long double YYEncodingTypeObject = 14, ///< id YYEncodingTypeClass = 15, ///< Class YYEncodingTypeSEL = 16, ///< SEL YYEncodingTypeBlock = 17, ///< block YYEncodingTypePointer = 18, ///< void* YYEncodingTypeStruct = 19, ///< struct YYEncodingTypeUnion = 20, ///< union YYEncodingTypeCString = 21, ///< char* YYEncodingTypeCArray = 22, ///< char[10] (for example) YYEncodingTypeQualifierMask = 0xFF00, ///< mask of qualifier YYEncodingTypeQualifierConst = 1 << 8, ///< const YYEncodingTypeQualifierIn = 1 << 9, ///< in YYEncodingTypeQualifierInout = 1 << 10, ///< inout YYEncodingTypeQualifierOut = 1 << 11, ///< out YYEncodingTypeQualifierBycopy = 1 << 12, ///< bycopy YYEncodingTypeQualifierByref = 1 << 13, ///< byref YYEncodingTypeQualifierOneway = 1 << 14, ///< oneway YYEncodingTypePropertyMask = 0xFF0000, ///< mask of property YYEncodingTypePropertyReadonly = 1 << 16, ///< readonly YYEncodingTypePropertyCopy = 1 << 17, ///< copy YYEncodingTypePropertyRetain = 1 << 18, ///< retain YYEncodingTypePropertyNonatomic = 1 << 19, ///< nonatomic YYEncodingTypePropertyWeak = 1 << 20, ///< weak YYEncodingTypePropertyCustomGetter = 1 << 21, ///< getter= YYEncodingTypePropertyCustomSetter = 1 << 22, ///< setter= YYEncodingTypePropertyDynamic = 1 << 23, ///< @dynamic }; 复制代码

@encode

Type Encodings 官方文档：@encode 是一个编译器指令，返回类型内部表示的字符串 ，例：@encode(int) = i ，其做用就是能够加快运行时库的消息分发。

附表：

Code	Meaning
c	char
i	int
s	short
l	long
q	long long
C	unsigned char
I	unsigned int
S	unsigned short
L	unsigned long
Q	unsigned long long
f	float
d	double
B	C++ bool or a C99 _Bool
v	void
*	character string (char *)
@	object (whether statically typed or typed id)
#	class object (Class)
:	method selector (SEL)
[array type]	array
{name=type...}	structure
(name=type...)	union
bnum	bit field of num bits
^type	pointer to type
?	unknown type (among other things, this code is used for function pointers)

备注：

1. 指针的标准编码是加一个前置的 ^ 。
2. 由于 C 字符串被认为是一个实体，而不是指针。 char * 拥有本身的编码 *
3. OC不支持 long double 类型，传入long double会和double同样返回d。。
4. BOOL 是 c ，而不是 i 。缘由是 Objective-C 设计之初每一个 bit 都比今天的要值钱, char 比 int 占位小。BOOL 更确切地说是 signed char （即便设置了 -funsigned-char 参数），以在不一样编译器之间保持一致，由于 char 能够是 signed 或者 unsigned 。
5. 直接传入 NSObject 会返回 {NSObject=#} 。可是传入 [NSObject class] 产生一个名为 NSObject 的只有一个类字段的结构体,就是实例变量 isa 。全部的 NSObject 实例都用它来表示本身的类型。
6. 数组类型例：包含12个float型指针的数组会返回 [12^f] 。
7. 结构体类型例:
   typedef struct example { id anObject; char *aString; int anInt; } Example;
   会返回
   {Example=@*i} 。
8. 结构指针的编码包含与结构字段相同数量的信息，7. 中的结构体指针会返回^{Example=@*i}

YYEncodingGetType

YYEncodingType YYEncodingGetType(const char *typeEncoding);
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typeEncoding 转为 YYEncodingType 的方法，方便使用。

YYClassIvarInfo

/**
 Instance variable information.
 */
@interface YYClassIvarInfo : NSObject
@property (nonatomic, assign, readonly) Ivar ivar;              ///< ivar opaque struct
@property (nonatomic, strong, readonly) NSString *name;         ///< Ivar's name @property (nonatomic, assign, readonly) ptrdiff_t offset; ///< Ivar's offset
@property (nonatomic, strong, readonly) NSString *typeEncoding; ///< Ivar's type encoding @property (nonatomic, assign, readonly) YYEncodingType type; ///< Ivar's type

/**
 Creates and returns an ivar info object.
 
 @param ivar ivar opaque struct
 @return A new object, or nil if an error occurs.
 */
- (instancetype)initWithIvar:(Ivar)ivar;
@end
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YYClassIvarInfo 是 objc_ivar 结构体的封装

先科普一下objc_ivar ，这是 Runtime 中表示变量的结构体

struct objc_ivar {
    char * _Nullable ivar_name OBJC2_UNAVAILABLE; // 名称
    char * _Nullable ivar_type OBJC2_UNAVAILABLE; // 类型
    int ivar_offset OBJC2_UNAVAILABLE; // 偏移字节
#ifdef __LP64__ // 若是已定义 __LP64__ 则表示正在构建 64 位目标
    int space OBJC2_UNAVAILABLE; // 变量空间
#endif
}
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说明以下：

属性名	说明
ivar	变量，对应 objc_ivar
name	变量名称，对应 ivar_name
offset	变量偏移字节，对应 ivar_offset
typeEncoding	变量类型编码，经过 ivar_getTypeEncoding 函数获得
type（扩展）	变量类型，经过 YYEncodingGetType 方法从类型编码中获得

YYClassMethodInfo

/**
 Method information.
 */
@interface YYClassMethodInfo : NSObject
@property (nonatomic, assign, readonly) Method method;                  ///< method opaque struct
@property (nonatomic, strong, readonly) NSString *name;                 ///< method name
@property (nonatomic, assign, readonly) SEL sel;                        ///< method's selector @property (nonatomic, assign, readonly) IMP imp; ///< method's implementation
@property (nonatomic, strong, readonly) NSString *typeEncoding;         ///< method's parameter and return types @property (nonatomic, strong, readonly) NSString *returnTypeEncoding; ///< return value's type
@property (nullable, nonatomic, strong, readonly) NSArray<NSString *> *argumentTypeEncodings; ///< array of arguments' type /** Creates and returns a method info object. @param method method opaque struct @return A new object, or nil if an error occurs. */ - (instancetype)initWithMethod:(Method)method; @end 复制代码

YYClassMethodInfo 是 objc_method 结构体的封装

先科普一下 objc_method ，这是 Runtime 中定义方法的结构体

struct objc_method {
      SEL method_name; // 方法名
      char *method_types; // 方法类型
      IMP method_imp; // 函数指针（方法实现）
  } 
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神奇的是 method_name 类型是SEL～
SEL是方法选择器 selector 的简。运行时，发消息就是发送SEL，根据SEL找到地址，最后调用方法。

具体怎么找的不用关注，猜想有多是方法和方法名字符串的映射～

说明以下：

属性名	说明
method	方法
name	方法名，对应method_name
sel	方法选择器
imp	函数指针（方法实现），对应 method_imp
typeEncoding	方法类型编码，对应 method_types
returnTypeEncoding	返回值类型编码
argumentTypeEncodings	参数类型编码，数组

YYClassPropertyInfo

/**
 Property information.
 */
@interface YYClassPropertyInfo : NSObject
@property (nonatomic, assign, readonly) objc_property_t property; ///< property's opaque struct @property (nonatomic, strong, readonly) NSString *name; ///< property's name
@property (nonatomic, assign, readonly) YYEncodingType type;      ///< property's type @property (nonatomic, strong, readonly) NSString *typeEncoding; ///< property's encoding value
@property (nonatomic, strong, readonly) NSString *ivarName;       ///< property's ivar name @property (nullable, nonatomic, assign, readonly) Class cls; ///< may be nil @property (nullable, nonatomic, strong, readonly) NSArray<NSString *> *protocols; ///< may nil @property (nonatomic, assign, readonly) SEL getter; ///< getter (nonnull) @property (nonatomic, assign, readonly) SEL setter; ///< setter (nonnull) /** Creates and returns a property info object. @param property property opaque struct @return A new object, or nil if an error occurs. */ - (instancetype)initWithProperty:(objc_property_t)property; @end 复制代码

YYClassPropertyInfo 是做者对 property_t 的封装，

先科普一下 property_t ，这是 Runtime 中表示属性的结构体。

struct property_t {
    const char *name; // 名称
    const char *attributes; // 修饰
};
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说明以下：

属性名	说明
property	property_t 结构体
name	属性名，对应 name
type（扩展）	属性类型
typeEncoding（扩展）	属性类型编码
ivarName（扩展）	变量名称
protocols（扩展）	协议
getter（扩展）	getter 方法选择器
setter（扩展）	setter 方法选择器

YYClassInfo

/**
 Class information for a class.
 */
@interface YYClassInfo : NSObject
@property (nonatomic, assign, readonly) Class cls; ///< class object
@property (nullable, nonatomic, assign, readonly) Class superCls; ///< super class object
@property (nullable, nonatomic, assign, readonly) Class metaCls;  ///< class's meta class object @property (nonatomic, readonly) BOOL isMeta; ///< whether this class is meta class @property (nonatomic, strong, readonly) NSString *name; ///< class name @property (nullable, nonatomic, strong, readonly) YYClassInfo *superClassInfo; ///< super class's class info
@property (nullable, nonatomic, strong, readonly) NSDictionary<NSString *, YYClassIvarInfo *> *ivarInfos; ///< ivars
@property (nullable, nonatomic, strong, readonly) NSDictionary<NSString *, YYClassMethodInfo *> *methodInfos; ///< methods
@property (nullable, nonatomic, strong, readonly) NSDictionary<NSString *, YYClassPropertyInfo *> *propertyInfos; ///< properties

/**
 If the class is changed (for example: you add a method to this class with
 'class_addMethod()'), you should call this method to refresh the class info cache.
 
 After called this method, `needUpdate` will returns `YES`, and you should call 
 'classInfoWithClass' or 'classInfoWithClassName' to get the updated class info.
 */
- (void)setNeedUpdate;

/**
 If this method returns `YES`, you should stop using this instance and call
 `classInfoWithClass` or `classInfoWithClassName` to get the updated class info.
 
 @return Whether this class info need update.
 */
- (BOOL)needUpdate;

/**
 Get the class info of a specified Class.
 
 @discussion This method will cache the class info and super-class info
 at the first access to the Class. This method is thread-safe.
 
 @param cls A class.
 @return A class info, or nil if an error occurs.
 */
+ (nullable instancetype)classInfoWithClass:(Class)cls;

/**
 Get the class info of a specified Class.
 
 @discussion This method will cache the class info and super-class info
 at the first access to the Class. This method is thread-safe.
 
 @param className A class name.
 @return A class info, or nil if an error occurs.
 */
+ (nullable instancetype)classInfoWithClassName:(NSString *)className;
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YYClassInfo 是做者对 objc_class 的封装，

先科普一下 objc_class ，这是 Runtime 中表示类的结构体。

typedef struct objc_class *Class;

// runtime.h
struct objc_class {
    Class _Nonnull isa OBJC_ISA_AVAILABILITY; // isa 指针

#if !__OBJC2__
    Class _Nullable super_class OBJC2_UNAVAILABLE; // 父类指针
    const char * _Nonnull name OBJC2_UNAVAILABLE; // 类名
    long version OBJC2_UNAVAILABLE; // 版本
    long info OBJC2_UNAVAILABLE; // 信息
    long instance_size OBJC2_UNAVAILABLE; // 空间大小
    struct objc_ivar_list * _Nullable ivars OBJC2_UNAVAILABLE; // 变量列表
    struct objc_method_list * _Nullable * _Nullable methodLists OBJC2_UNAVAILABLE; // 方法列表
    struct objc_cache * _Nonnull cache OBJC2_UNAVAILABLE; // 缓存
    struct objc_protocol_list * _Nullable protocols OBJC2_UNAVAILABLE; // 协议列表
#endif

} OBJC2_UNAVAILABLE;
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说明以下：

属性名	说明
cls	类
superCls	父类
metaCls	元类
isMeta	自身是否元类
name	类名
superClassInfo	父类的信息
ivarInfos	变量信息
methodInfos	方法信息
propertyInfos	属性信息