前言
YYModel 是一个iOS JSON模型转化库，和其他一些同类型库相比，具有比较好的性能优势。本文会对YYModel的源码进行分析，具体用法作者ibireme在github中有提及。YYModel的目录结构很简单，只有两个类, NSObject+YYModel 和 YYClassInfo。YYClassInfo主要对根类NSObject 的 Ivar , Method, Property以及Class本身进行了封装，NSObject+YYModel 是 NSObject的分类，扩展了一些JSON模型转化的方法。下图一张YYmodel的整体结构图：
YYModel 结构图.png
YYClassInfo
要点
YYClassIvarInfo : 对 Class的Ivar进行了封装
YYClassMethodInfo : 对 Class的Method进行了封装
YYClassPropertyInfo : 对 Class的Property进行了封装
YYClassInfo : 对Class进行了封装，包含了YYClassIvarInfo，YYClassMethodInfo，YYClassPropertyInfo
变量类型编码
说到变量，可能我们写代码中最常见的就是变量了。当我们自定义一个类时，首先总是会申明一些属性，而且每个属性都会带有一些修饰词。比如是否原子性，内存管理原则，只读性。这些都可以通过这个属性的property_getAttributes 方法获取，苹果为所有的类型，包括属性类型都有编码，具体可以查看苹果官方文档:类型编码, 苹果官方文档:属性类型。 下面是一个简单例子：
- 申明属性
@interface Cat : NSObject
@end
@interface Person : NSObject
@property (nonatomic,copy) NSString *name;
@property (nonatomic,assign) NSInteger age;
@property (nonatomic,strong) Cat *cat;
- (NSDictionary *)getProperties;
@end
2.通过runtime 来获取所有属性
#import "Person.h"
#import <objc/runtime.h>
@implementation Person
- (NSDictionary *) getProperties{
NSMutableDictionary *dic = [NSMutableDictionary dictionary];
unsigned int count = 0;
objc_property_t *propertyList = class_copyPropertyList([self class], &count);
for (NSUInteger i = 0; i < count; i++) {
const char *name = property_getName(propertyList[i]);
const char *attribute = property_getAttributes(propertyList[i]);
NSString *nameStr = [NSString stringWithUTF8String:name];
NSString *attributeStr = [NSString stringWithUTF8String:attribute];
dic[nameStr] = attributeStr;
}
return [dic copy];
}
@end
3.打印结果
2017-01-03 10:54:34.690 Properties[16941:881462] {
age = "Tq,N,V_age";
cat = "T@\"Cat\",&,N,V_cat";
name = "T@\"NSString\",C,N,V_name";
}
我们可以看到属性的所有类型编码信息，其中第一个代表是这个变量的类型，以T开头，最后一个代表的是变量的名字，一般用V_属性名表示，中间的部分就是我们声明的修饰符。比如age的类型是 Tq，而在官方文档中q 代表了A long long,64bit下NSInteger的取值范围就是long == long long ，N代表了非原子性，变量名是_age。其他的@代表了OC类型 id ,cat类型即是T@"Cat"，&代表了 这个变量是retain （ARC下strong相当于retain），C 代表了copy
YYEncodingType
根据类型编码自定义了类型枚举，包含了三个部分
YYEncodingTypeMask : 0~8位的值，变量的数据类型
YYEncodingTypeQualifierMask : 8~16位的值，变量的方法类型
YYEncodingTypePropertyMask: 16~24位的值，变量的属性类型
这里把枚举值分成三个部分，通过 枚举值 & 对应 Mask 取出对应的变量类型，区分不同类型部分。YYEncodingGetType 是根据变量的数据类型编码值获取自定义YYEncodingType
Var Method Property
YYClassIvarInfo：用于存取变量的信息
/**
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
Ivar是表示实例变量的类型，其实际是一个指向objc_ivar结构体的指针，其定义如下：
struct objc_ivar {
charchar *ivar_name OBJC2_UNAVAILABLE;
charchar *ivar_type OBJC2_UNAVAILABLE;
int ivar_offset OBJC2_UNAVAILABLE;
#ifdef __LP64__
int space OBJC2_UNAVAILABLE;
#endif
}
运用runtime,name通过的ivar_getName获取，offset 通过ivar_getOffset获取，typeEncoding 通过 ivar_getTypeEncoding 获取，type 通过自定义方法 YYEncodingGetType获取。其中offset是变量的基地址偏移量，可以通过它来直接访问变量数据,下面是例子：
Person *p = [[Person alloc]init];
// NSLog(@"%@",[p getProperties]);
p.age = 20;
Ivar age_ivar = class_getInstanceVariable([Person class], "_age");
long *age_pointer = (long *)((__bridge void *)(p) + ivar_getOffset(age_ivar));
NSLog(@"age ivar offset = %td", ivar_getOffset(age_ivar));
*age_pointer = 10;
NSLog(@"%@", p);
- (NSString *)description {
NSLog(@"current pointer = %p", self);
NSLog(@"age pointer = %p", &_age);
return [NSString stringWithFormat:@"age = %zi", _age];
}
打印结果：
2017-01-03 14:41:14.175 Properties[20934:1554728] age ivar offset = 16
2017-01-03 14:41:14.176 Properties[20934:1554728] current pointer = 0x600000075140
2017-01-03 14:41:14.176 Properties[20934:1554728] age pointer = 0x600000075150
2017-01-03 14:41:14.177 Properties[20934:1554728] age = 10
YYClassMethodInfo：用于存取方法的信息
/**
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
Method 的信息同 Ivar 一样，通过runtime的 method相关方法获取，其他的一些信息同Ivar，主要来说一下 SEL和 Imp
SEL: 方法ID，C字符串
typedef struct objc_selector *SEL;
/// Defines a method
struct objc_method_description {
SEL name; /**< The name of the method */
char *types; /**< The types of the method arguments */
};
IMP：方法函数指针
OC是动态语言，方法调用（也叫做消息发送）是在运行时动态绑定的，而非编译时。如何做到正确的调用指定的方法呢？这里就需要用到SEL和IMP。编译器会将消息发送转换成对objc_msgSend(void /* id self, SEL op, ... */ )方法的调用 。objc_msgSend方法根据对象的isa指针找到对象的类，通过在类中的调度表（dispatch table）中查找SEL 获得 IMP,精确执行指定方法。
YYClassPropertyInfo: 用于存取属性的信息
/**
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
YYClassInfo: 对Class的封装，包含了上面三部分的信息
/**
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
元类
其中有metaCls代表了元类。那什么是元类呢？下面是一张经典的类结构图
isa.png
在OC中，每个实例对象都有一个isa指针，它指向了对象的class。而这个class也同样有一个isa指针，它就是指向了它的元类，其实类也是一个对象，所以对象之于类的关系，就相当于类（类对象）之于其元类（类对象的类）的关系。那元类有什么用呢？我们都知道在OC中调用方法有实例方法和类方法。我们调用实例方法，就是通过isa指针找到指定的class，查找存储在class中的方法列表执行方法，所以元类的作用就是调用类方法时，通过查找保存在元类中的类方法执行方法的作用。那为什么不把所有方法都保存在类中，可能这样更加高效也节省资源吧，具体可以自己查找资料。
在YYClassInfo中，有一个_update方法，用来更新类中存储的信息。
初始化方法
+ (instancetype)classInfoWithClass:(Class)cls {
if (!cls) return nil;
static CFMutableDictionaryRef classCache;
static CFMutableDictionaryRef metaCache;
static dispatch_once_t onceToken;
static dispatch_semaphore_t lock;
dispatch_once(&onceToken, ^{
classCache = CFDictionaryCreateMutable(CFAllocatorGetDefault(), 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
metaCache = CFDictionaryCreateMutable(CFAllocatorGetDefault(), 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
lock = dispatch_semaphore_create(1);
});
dispatch_semaphore_wait(lock, DISPATCH_TIME_FOREVER);
YYClassInfo *info = CFDictionaryGetValue(class_isMetaClass(cls) ? metaCache : classCache, (__bridge const void *)(cls));
if (info && info->_needUpdate) {
[info _update];
}
dispatch_semaphore_signal(lock);
if (!info) {
info = [[YYClassInfo alloc] initWithClass:cls];
if (info) {
dispatch_semaphore_wait(lock, DISPATCH_TIME_FOREVER);
CFDictionarySetValue(info.isMeta ? metaCache : classCache, (__bridge const void *)(cls), (__bridge const void *)(info));
dispatch_semaphore_signal(lock);
}
}
return info;
}
要点:
CFDictionaryCreateMutable 和 CFDictionarySetValue 不是线程安全的，所以需要创建锁，采用
dispatch_semaphore通过控制信号量实现了锁设置缓存，如果在缓存中存在class，则直接获取到对应的ivar，method，property，否者创建YYClassInfo实例对象
NSObject+YYModel:
NSObject+YYModel是YYModel的核心类，主要部分：
强制内联C函数：功能函数
私有类_YYModelPropertyMeta : 管理Model属性的数据, 类型, 映射的key，keyPath
私有类 _YYModelMeta :管理Model 数据,类型,存储 映射key,keypath，_YYModelPropertyMeta
NSObject NSArray NSDictionary (YYModel) : 几个分类，YYModel主体功能实现
YYModel 协议：扩展功能实现
私有类_YYModelPropertyMeta
_YYModelPropertyMeta是对上面的 YYClassPropertyInfo 的进一步封装。
内部实例变量
/// A property info in object model.
// model property的进一步分装
@interface _YYModelPropertyMeta : NSObject {
@package
NSString *_name; //属性名
YYEncodingType _type; //属性的编码类型
YYEncodingNSType _nsType; //属性的Foundation类型
BOOL _isCNumber; //是否c语言的数字
Class _cls; //属性的class
Class _genericCls; //属性内包含的类class
SEL _getter; //属性 getter方法
SEL _setter; //属性 setter方法
BOOL _isKVCCompatible; //是否可以使用KVC
BOOL _isStructAvailableForKeyedArchiver; //是否struct并且可以归档
BOOL _hasCustomClassFromDictionary; //是否包含本本地的class转换
/*
property->key:
_mappedToKey:key _mappedToKeyPath:nil _mappedToKeyArray:nil
property->keyPath:
_mappedToKey:keyPath _mappedToKeyPath:keyPath(array) _mappedToKeyArray:nil
property->keys:
_mappedToKey:keys[0] _mappedToKeyPath:nil/keyPath _mappedToKeyArray:keys(array)
*/
NSString *_mappedToKey; //属性名映射的 key
NSArray *_mappedToKeyPath; //属性名映射的 keyPath
NSArray *_mappedToKeyArray; //属性名的映射的key keyPath 数组
YYClassPropertyInfo *_info; //属性的YYClassPropertyInfo info
_YYModelPropertyMeta *_next;
//多个属性名映射到同一个key 时，指向下一个属性名的YYModelPropertyMeta 指针
}
@end
主要是最后几个变量。其中_mappedToKey _mappedToKeyPath _mappedToKeyArray 是属性映射的key，keyPath ，key (keypath) 数组_mappedToKeyArray 中可以是key和keyPath，实际取其中第一个映射到的值
一般一个属性名对应一个key值，如果多个属性名对应同一个key，这里就需要next发挥作用了。比如
{
@"name1" : @"name",
@"name2" : @"name",
@"name3" : @"name",
}
首先name1最先得到映射，对mapKey进行赋值，取得json中的name字段进行赋值一系列操作，此时next指针为nil
name2接着进行映射，对mapKey进行赋值，接着取得原来json key对应的属性描述对象，将name2的next指针，指向name1。
name3接着进行映射，对mapKey进行赋值，接着取得原来json key对应的属性描述对象，将name3的next指针，指向name2。
代码中的实现
propertyMeta->_next = mapper[mappedToKey] ?: nil;
mapper[mappedToKey] = propertyMeta;
初始化方法
@implementation _YYModelPropertyMeta
+ (instancetype)metaWithClassInfo:(YYClassInfo *)classInfo propertyInfo:(YYClassPropertyInfo *)propertyInfo generic:(Class)generic {
//创建并且根据propertyInfo 进行变量赋值
_YYModelPropertyMeta *meta = [self new];
meta->_name = propertyInfo.name;
meta->_type = propertyInfo.type;
meta->_info = propertyInfo;
// 属性为容器类型的时候， 映射类型赋值
meta->_genericCls = generic;
if ((meta->_type & YYEncodingTypeMask) == YYEncodingTypeObject) {
// 是否Foundation 类型
meta->_nsType = YYClassGetNSType(propertyInfo.cls);
} else {
// 是否C数据类型
meta->_isCNumber = YYEncodingTypeIsCNumber(meta->_type);
}
// 属性为结构体类型
if ((meta->_type & YYEncodingTypeMask) == YYEncodingTypeStruct) {
/*
It seems that NSKeyedUnarchiver cannot decode NSValue except these structs:
*/
static NSSet *types = nil;
static dispatch_once_t onceToken;
// 单例 创建C结构体类型映射
dispatch_once(&onceToken, ^{
NSMutableSet *set = [NSMutableSet new];
// 32 bit
[set addObject:@"{CGSize=ff}"];
[set addObject:@"{CGPoint=ff}"];
[set addObject:@"{CGRect={CGPoint=ff}{CGSize=ff}}"];
[set addObject:@"{CGAffineTransform=ffffff}"];
[set addObject:@"{UIEdgeInsets=ffff}"];
[set addObject:@"{UIOffset=ff}"];
// 64 bit
[set addObject:@"{CGSize=dd}"];
[set addObject:@"{CGPoint=dd}"];
[set addObject:@"{CGRect={CGPoint=dd}{CGSize=dd}}"];
[set addObject:@"{CGAffineTransform=dddddd}"];
[set addObject:@"{UIEdgeInsets=dddd}"];
[set addObject:@"{UIOffset=dd}"];
types = set;
});
// 只有上面结构体才能被归档
if ([types containsObject:propertyInfo.typeEncoding]) {
meta->_isStructAvailableForKeyedArchiver = YES;
}
}
// 设置class类型
meta->_cls = propertyInfo.cls;
// 如果是容器类型
if (generic) {
// 从容器class 中读取
meta->_hasCustomClassFromDictionary = [generic respondsToSelector:@selector(modelCustomClassForDictionary:)];
} else if (meta->_cls && meta->_nsType == YYEncodingTypeNSUnknown) {
// 从class类型中读取
meta->_hasCustomClassFromDictionary = [meta->_cls respondsToSelector:@selector(modelCustomClassForDictionary:)];
}
// 设置 getter 和 setter 方法
if (propertyInfo.getter) {
if ([classInfo.cls instancesRespondToSelector:propertyInfo.getter]) {
meta->_getter = propertyInfo.getter;
}
}
if (propertyInfo.setter) {
if ([classInfo.cls instancesRespondToSelector:propertyInfo.setter]) {
meta->_setter = propertyInfo.setter;
}
}
/**
* 只有实现了getter和setter方法 才能实现归档
*/
if (meta->_getter && meta->_setter) {
/*
类型是否支持 KVC
*/
switch (meta->_type & YYEncodingTypeMask) {
case YYEncodingTypeBool:
case YYEncodingTypeInt8:
case YYEncodingTypeUInt8:
case YYEncodingTypeInt16:
case YYEncodingTypeUInt16:
case YYEncodingTypeInt32:
case YYEncodingTypeUInt32:
case YYEncodingTypeInt64:
case YYEncodingTypeUInt64:
case YYEncodingTypeFloat:
case YYEncodingTypeDouble:
case YYEncodingTypeObject:
case YYEncodingTypeClass:
case YYEncodingTypeBlock:
case YYEncodingTypeStruct:
case YYEncodingTypeUnion: {
meta->_isKVCCompatible = YES;
} break;
default: break;
}
}
return meta;
}
@end
私有类_YYModelMeta
_YYModelMeta 是对 YYClassInfo 的再次封装
内部变量
@interface _YYModelMeta : NSObject {
@package
YYClassInfo *_classInfo;
// key: 映射的 json key ,keyPath value： _YYModelPropertyMeta
NSDictionary *_mapper;
// model所有属性的PropertyMetas
NSArray *_allPropertyMetas;
//model所有映射son keyPath 属性 的PropertyMetas
NSArray *_keyPathPropertyMetas;
// model所有映射多个key 属性 的PropertyMetas
NSArray *_multiKeysPropertyMetas;
/// 需要映射的属性总个数
NSUInteger _keyMappedCount;
/// Model对应的Foundation 类型
YYEncodingNSType _nsType;
// 事否实现了自定义的映射关系表
BOOL _hasCustomWillTransformFromDictionary;
BOOL _hasCustomTransformFromDictionary;
BOOL _hasCustomTransformToDictionary;
BOOL _hasCustomClassFromDictionary;
}
@end
初始化
/// Returns the cached model class meta
+ (instancetype)metaWithClass:(Class)cls {
if (!cls) return nil;
static CFMutableDictionaryRef cache;
static dispatch_once_t onceToken;
static dispatch_semaphore_t lock;
dispatch_once(&onceToken, ^{
cache = CFDictionaryCreateMutable(CFAllocatorGetDefault(), 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
lock = dispatch_semaphore_create(1);
});
dispatch_semaphore_wait(lock, DISPATCH_TIME_FOREVER);
_YYModelMeta *meta = CFDictionaryGetValue(cache, (__bridge const void *)(cls));
dispatch_semaphore_signal(lock);
if (!meta || meta->_classInfo.needUpdate) {
meta = [[_YYModelMeta alloc] initWithClass:cls];
if (meta) {
dispatch_semaphore_wait(lock, DISPATCH_TIME_FOREVER);
CFDictionarySetValue(cache, (__bridge const void *)(cls), (__bridge const void *)(meta));
dispatch_semaphore_signal(lock);
}
}
return meta;
}
首先从缓存中加载，没有在根据传入cls 创建meta，并做缓存处理， dispatch_semaphore 确保线程安全
@implementation _YYModelMeta
- (instancetype)initWithClass:(Class)cls {
YYClassInfo *classInfo = [YYClassInfo classInfoWithClass:cls];
if (!classInfo) return nil;
self = [super init];
// 黑名单 会忽略返回数组里的属性
NSSet *blacklist = nil;
if ([cls respondsToSelector:@selector(modelPropertyBlacklist)]) {
NSArray *properties = [(id<YYModel>)cls modelPropertyBlacklist];
if (properties) {
blacklist = [NSSet setWithArray:properties];
}
}
// 白名单 只考虑返回数组内的属性
NSSet *whitelist = nil;
if ([cls respondsToSelector:@selector(modelPropertyWhitelist)]) {
NSArray *properties = [(id<YYModel>)cls modelPropertyWhitelist];
if (properties) {
whitelist = [NSSet setWithArray:properties];
}
}
// 获取容器属性中的映射关系字典
NSDictionary *genericMapper = nil;
// 判断类中是否实现了对应的modelContainerPropertyGenericClass方法
if ([cls respondsToSelector:@selector(modelContainerPropertyGenericClass)]) {
genericMapper = [(id<YYModel>)cls modelContainerPropertyGenericClass];
// 存储key和对应的class到字典中
if (genericMapper) {
NSMutableDictionary *tmp = [NSMutableDictionary new];
[genericMapper enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
if (![key isKindOfClass:[NSString class]]) return;
Class meta = object_getClass(obj);
if (!meta) return;
if (class_isMetaClass(meta)) {
tmp[key] = obj;
} else if ([obj isKindOfClass:[NSString class]]) {
Class cls = NSClassFromString(obj);
if (cls) {
tmp[key] = cls;
}
}
}];
genericMapper = tmp;
}
}
// 存储所有属性的PropertyMeta对象
NSMutableDictionary *allPropertyMetas = [NSMutableDictionary new];
YYClassInfo *curClassInfo = classInfo;
while (curClassInfo && curClassInfo.superCls != nil) { // recursive parse super class, but ignore root class (NSObject/NSProxy)
// 遍历当前ClassInfo 中的所有PropertyInfo， 将它们封装成PropertyMeta
for (YYClassPropertyInfo *propertyInfo in curClassInfo.propertyInfos.allValues) {
// 检查是否合法和黑白名单筛选
if (!propertyInfo.name) continue;
if (blacklist && [blacklist containsObject:propertyInfo.name]) continue;
if (whitelist && ![whitelist containsObject:propertyInfo.name]) continue;
// 通过propetyInfo来创建PropertyMeta 对象
_YYModelPropertyMeta *meta = [_YYModelPropertyMeta metaWithClassInfo:classInfo
propertyInfo:propertyInfo
generic:genericMapper[propertyInfo.name]];
// meta name非空
if (!meta || !meta->_name) continue;
// 需要实现get方法和set方法
if (!meta->_getter || !meta->_setter) continue;
// 字典中已有该字段的meta 避免重复操作
if (allPropertyMetas[meta->_name]) continue;
allPropertyMetas[meta->_name] = meta;
}
// 遍历父类的property
curClassInfo = curClassInfo.superClassInfo;
}
if (allPropertyMetas.count)
_allPropertyMetas = allPropertyMetas.allValues.copy;
// 创建 key ：propertyMeta 映射关系字典
NSMutableDictionary *mapper = [NSMutableDictionary new];
NSMutableArray *keyPathPropertyMetas = [NSMutableArray new];
NSMutableArray *multiKeysPropertyMetas = [NSMutableArray new];
// 是否实现自定义的映射表
if ([cls respondsToSelector:@selector(modelCustomPropertyMapper)]) {
NSDictionary *customMapper = [(id <YYModel>)cls modelCustomPropertyMapper];
// 遍历自定义的字典
[customMapper enumerateKeysAndObjectsUsingBlock:^(NSString *propertyName, NSString *mappedToKey, BOOL *stop) {
_YYModelPropertyMeta *propertyMeta = allPropertyMetas[propertyName];
if (!propertyMeta) return;
// 由于用户自定义映射，把原来映射的数据删除
[allPropertyMetas removeObjectForKey:propertyName];
if ([mappedToKey isKindOfClass:[NSString class]]) {
// key字段非空
if (mappedToKey.length == 0) return;
// 保存映射的key
propertyMeta->_mappedToKey = mappedToKey;
// 如果是keyPath的情况处理
NSArray *keyPath = [mappedToKey componentsSeparatedByString:@"."];
if (keyPath.count > 1) {
propertyMeta->_mappedToKeyPath = keyPath;
[keyPathPropertyMetas addObject:propertyMeta];
}
// 多个属性映射同一个key的时候，用next存储前一个 json Key映射的meta
propertyMeta->_next = mapper[mappedToKey] ?: nil;
// 保存新的meta对象
mapper[mappedToKey] = propertyMeta;
} else if ([mappedToKey isKindOfClass:[NSArray class]]) {
// 一个属性映射多个json Key
NSMutableArray *mappedToKeyArray = [NSMutableArray new];
for (NSString *oneKey in ((NSArray *)mappedToKey)) {
if (![oneKey isKindOfClass:[NSString class]]) continue;
if (oneKey.length == 0) continue;
NSArray *keyPath = [oneKey componentsSeparatedByString:@"."];
if (keyPath.count > 1) {
[mappedToKeyArray addObject:keyPath];
} else {
[mappedToKeyArray addObject:oneKey];
}
if (!propertyMeta->_mappedToKey) {
propertyMeta->_mappedToKey = oneKey;
propertyMeta->_mappedToKeyPath = keyPath.count > 1 ? keyPath : nil;
}
}
if (!propertyMeta->_mappedToKey) return;
propertyMeta->_mappedToKeyArray = mappedToKeyArray;
[multiKeysPropertyMetas addObject:propertyMeta];
propertyMeta->_next = mapper[mappedToKey] ?: nil;
mapper[mappedToKey] = propertyMeta;
}
}];
}
// 没有自定义映射规则的属性处理
[allPropertyMetas enumerateKeysAndObjectsUsingBlock:^(NSString *name, _YYModelPropertyMeta *propertyMeta, BOOL *stop) {
// 直接让mappedKey等于属性名
propertyMeta->_mappedToKey = name;
propertyMeta->_next = mapper[name] ?: nil;
mapper[name] = propertyMeta;
}];
// 变量存储
if (mapper.count) _mapper = mapper;
if (keyPathPropertyMetas) _keyPathPropertyMetas = keyPathPropertyMetas;
if (multiKeysPropertyMetas) _multiKeysPropertyMetas = multiKeysPropertyMetas;
_classInfo = classInfo;
_keyMappedCount = _allPropertyMetas.count;
_nsType = YYClassGetNSType(cls);
_hasCustomWillTransformFromDictionary = ([cls instancesRespondToSelector:@selector(modelCustomWillTransformFromDictionary:)]);
_hasCustomTransformFromDictionary = ([cls instancesRespondToSelector:@selector(modelCustomTransformFromDictionary:)]);
_hasCustomTransformToDictionary = ([cls instancesRespondToSelector:@selector(modelCustomTransformToDictionary:)]);
_hasCustomClassFromDictionary = ([cls respondsToSelector:@selector(modelCustomClassForDictionary:)]);
return self;
}
JSON 转 Model
+ (instancetype)yy_modelWithJSON:(id)son {
NSDictionary *dic = [self _yy_dictionaryWithJSON:json];
return [self yy_modelWithDictionary:dic];
}
传入的json可以是 NSDictionary, NSString , NSData，_yy_dictionaryWithJSON 统一转化成字典
+ (instancetype)yy_modelWithDictionary:(NSDictionary *)dictionary {
//字典合法性校验
if (!dictionary || dictionary == (id)kCFNull) return nil;
if (![dictionary isKindOfClass:[NSDictionary class]]) return nil;
Class cls = [self class];
//创建 model 元数据
_YYModelMeta *modelMeta = [_YYModelMeta metaWithClass:cls];
//自定义字典
if (modelMeta->_hasCustomClassFromDictionary) {
cls = [cls modelCustomClassForDictionary:dictionary] ?: cls;
}
// 根据dictionary 进行 model 属性赋值
NSObject *one = [cls new];
if ([one yy_modelSetWithDictionary:dictionary]) return one;
return nil;
}
结构体 ModelSetContext 存储 modelMeta ，model， dic 作为 CFDictionaryApplyFunction 和 CFArrayApplyFunction 的context 参数，传递数据
- (BOOL)yy_modelSetWithDictionary:(NSDictionary *)dic {
// 合法性检验
if (!dic || dic == (id)kCFNull) return NO;
if (![dic isKindOfClass:[NSDictionary class]]) return NO;
_YYModelMeta *modelMeta = [_YYModelMeta metaWithClass:object_getClass(self)];
if (modelMeta->_keyMappedCount == 0) return NO;
if (modelMeta->_hasCustomWillTransformFromDictionary) {
dic = [((id<YYModel>)self) modelCustomWillTransformFromDictionary:dic];
if (![dic isKindOfClass:[NSDictionary class]]) return NO;
}
ModelSetContext context = {0};
context.modelMeta = (__bridge void *)(modelMeta);
context.model = (__bridge void *)(self);
context.dictionary = (__bridge void *)(dic);
if (modelMeta->_keyMappedCount >= CFDictionaryGetCount((CFDictionaryRef)dic)) {
//映射的key Count >= dic Count
CFDictionaryApplyFunction((CFDictionaryRef)dic, ModelSetWithDictionaryFunction, &context);
if (modelMeta->_keyPathPropertyMetas) {
CFArrayApplyFunction((CFArrayRef)modelMeta->_keyPathPropertyMetas,
CFRangeMake(0, CFArrayGetCount((CFArrayRef)modelMeta->_keyPathPropertyMetas)),
ModelSetWithPropertyMetaArrayFunction,
&context);
}
if (modelMeta->_multiKeysPropertyMetas) {
CFArrayApplyFunction((CFArrayRef)modelMeta->_multiKeysPropertyMetas,
CFRangeMake(0, CFArrayGetCount((CFArrayRef)modelMeta->_multiKeysPropertyMetas)),
ModelSetWithPropertyMetaArrayFunction,
&context);
}
} else {
//映射的key Count < dic Count
CFArrayApplyFunction((CFArrayRef)modelMeta->_allPropertyMetas,
CFRangeMake(0, modelMeta->_keyMappedCount),
ModelSetWithPropertyMetaArrayFunction,
&context);
}
if (modelMeta->_hasCustomTransformFromDictionary) {
return [((id<YYModel>)self) modelCustomTransformFromDictionary:dic];
}
return YES;
}
调用CoreFoundation 的 CFDictionaryApplyFunction 和 CFArrayApplyFunction 回调自定义的 Apply function
static void ModelSetWithDictionaryFunction(const void *_key, const void *_value, void *_context) 和 static void ModelSetWithPropertyMetaArrayFunction(const void *_propertyMeta, void *_context)
根据获得的value ，model ，_propertyMeta 最后统一调用 下面方法，运用runtime的 objc_msgSend 设置model属性
static void ModelSetValueForProperty(__unsafe_unretained id model,
__unsafe_unretained id value,
__unsafe_unretained _YYModelPropertyMeta *meta)
自定义的CFDictionaryApplyFunction 的回调方法，CoreFoundation中的原回调函数
typedef void (*CFDictionaryApplierFunction)(const void *key, const void *value, void *context);
/**
Apply function for dictionary, to set the key-value pair to model.
@param _key should not be nil, NSString.
@param _value should not be nil.
@param _context _context.modelMeta and _context.model should not be nil.
*/
static void ModelSetWithDictionaryFunction(const void *_key, const void *_value, void *_context) {
ModelSetContext *context = _context;
__unsafe_unretained _YYModelMeta *meta = (__bridge _YYModelMeta *)(context->modelMeta);
__unsafe_unretained _YYModelPropertyMeta *propertyMeta = [meta->_mapper objectForKey:(__bridge id)(_key)];
__unsafe_unretained id model = (__bridge id)(context->model);
while (propertyMeta) {
if (propertyMeta->_setter) {
ModelSetValueForProperty(model, (__bridge __unsafe_unretained id)_value, propertyMeta);
}
propertyMeta = propertyMeta->_next;
};
}
自定义的CFArrayApplyFunction 的回调方法，CoreFoundation中的原回调函数
typedef void (*CFArrayApplierFunction)(const void *value, void *context);
/**
Apply function for model property meta, to set dictionary to model.
@param _propertyMeta should not be nil, _YYModelPropertyMeta.
@param _context _context.model and _context.dictionary should not be nil.
*/
static void ModelSetWithPropertyMetaArrayFunction(const void *_propertyMeta, void *_context) {
ModelSetContext *context = _context;
__unsafe_unretained NSDictionary *dictionary = (__bridge NSDictionary *)(context->dictionary);
__unsafe_unretained _YYModelPropertyMeta *propertyMeta = (__bridge _YYModelPropertyMeta *)(_propertyMeta);
if (!propertyMeta->_setter) return;
id value = nil;
if (propertyMeta->_mappedToKeyArray) {
//从dic中获取映射多个key的值,返回映射到的第一个值
value = YYValueForMultiKeys(dictionary, propertyMeta->_mappedToKeyArray);
} else if (propertyMeta->_mappedToKeyPath) {
//从dic中获取映射keypath的值
value = YYValueForKeyPath(dictionary, propertyMeta->_mappedToKeyPath);
} else {
//从dic中获取映射key的值
value = [dictionary objectForKey:propertyMeta->_mappedToKey];
}
if (value) {
//Model 属性赋值
__unsafe_unretained id model = (__bridge id)(context->model);
ModelSetValueForProperty(model, value, propertyMeta);
}
}
最终实现model 属性赋值。 该方法比较长，首先对 meta的属性类型进行判断，主要分为三类，
- C基本数据类型
- Foundation 类型
- 其他类型，如 id， Class ，block，SEL等等
根据类型获取对应value，
最后都调用 ((void (*)(id, SEL, id))(void *) objc_msgSend)((id)model, meta->_setter, (id)value) 进行model 属性赋值
static void ModelSetValueForProperty(__unsafe_unretained id model,
__unsafe_unretained id value,
__unsafe_unretained _YYModelPropertyMeta *meta)
Model 转 JSON
其中有效的JSON Object 只能是以下类型：
NSArray，NSDictionary，NSString，NSNumber，NSNull。
1.如果是NSDictionary,NSSet,NSArray 类型，递归调用此方法获得JSON Object
2.如果是NSURL，NSAttributedString ，NSDate， NSData，做简单相应返回
3.根据Model类型创建modelMeta，取实例变量_mapper获取所有属性名和｀propertyMeta,再根据propertyMeta的 类型_type获得相应的value, 根据有无_mappedToKeyPath再进一步处理，赋值，最后 判断有无自定义_hasCustomTransformToDictionary，返回最终转化结果
主要方法：
static id ModelToJSONObjectRecursive(NSObject *model) {
if (!model || model == (id)kCFNull) return model;
if ([model isKindOfClass:[NSString class]]) return model;
if ([model isKindOfClass:[NSNumber class]]) return model;
if ([model isKindOfClass:[NSDictionary class]]) {
if ([NSJSONSerialization isValidJSONObject:model]) return model;
NSMutableDictionary *newDic = [NSMutableDictionary new];
[((NSDictionary *)model) enumerateKeysAndObjectsUsingBlock:^(NSString *key, id obj, BOOL *stop) {
NSString *stringKey = [key isKindOfClass:[NSString class]] ? key : key.description;
if (!stringKey) return;
id jsonObj = ModelToJSONObjectRecursive(obj);
if (!jsonObj) jsonObj = (id)kCFNull;
newDic[stringKey] = jsonObj;
}];
return newDic;
}
if ([model isKindOfClass:[NSSet class]]) {
NSArray *array = ((NSSet *)model).allObjects;
if ([NSJSONSerialization isValidJSONObject:array]) return array;
NSMutableArray *newArray = [NSMutableArray new];
for (id obj in array) {
if ([obj isKindOfClass:[NSString class]] || [obj isKindOfClass:[NSNumber class]]) {
[newArray addObject:obj];
} else {
id jsonObj = ModelToJSONObjectRecursive(obj);
if (jsonObj && jsonObj != (id)kCFNull) [newArray addObject:jsonObj];
}
}
return newArray;
}
if ([model isKindOfClass:[NSArray class]]) {
if ([NSJSONSerialization isValidJSONObject:model]) return model;
NSMutableArray *newArray = [NSMutableArray new];
for (id obj in (NSArray *)model) {
if ([obj isKindOfClass:[NSString class]] || [obj isKindOfClass:[NSNumber class]]) {
[newArray addObject:obj];
} else {
id jsonObj = ModelToJSONObjectRecursive(obj);
if (jsonObj && jsonObj != (id)kCFNull) [newArray addObject:jsonObj];
}
}
return newArray;
}
if ([model isKindOfClass:[NSURL class]]) return ((NSURL *)model).absoluteString;
if ([model isKindOfClass:[NSAttributedString class]]) return ((NSAttributedString *)model).string;
if ([model isKindOfClass:[NSDate class]]) return [YYISODateFormatter() stringFromDate:(id)model];
if ([model isKindOfClass:[NSData class]]) return nil;
_YYModelMeta *modelMeta = [_YYModelMeta metaWithClass:[model class]];
if (!modelMeta || modelMeta->_keyMappedCount == 0) return nil;
NSMutableDictionary *result = [[NSMutableDictionary alloc] initWithCapacity:64];
__unsafe_unretained NSMutableDictionary *dic = result; // avoid retain and release in block
[modelMeta->_mapper enumerateKeysAndObjectsUsingBlock:^(NSString *propertyMappedKey, _YYModelPropertyMeta *propertyMeta, BOOL *stop) {
if (!propertyMeta->_getter) return;
id value = nil;
if (propertyMeta->_isCNumber) {
value = ModelCreateNumberFromProperty(model, propertyMeta);
} else if (propertyMeta->_nsType) {
id v = ((id (*)(id, SEL))(void *) objc_msgSend)((id)model, propertyMeta->_getter);
value = ModelToJSONObjectRecursive(v);
} else {
switch (propertyMeta->_type & YYEncodingTypeMask) {
case YYEncodingTypeObject: {
id v = ((id (*)(id, SEL))(void *) objc_msgSend)((id)model, propertyMeta->_getter);
value = ModelToJSONObjectRecursive(v);
if (value == (id)kCFNull) value = nil;
} break;
case YYEncodingTypeClass: {
Class v = ((Class (*)(id, SEL))(void *) objc_msgSend)((id)model, propertyMeta->_getter);
value = v ? NSStringFromClass(v) : nil;
} break;
case YYEncodingTypeSEL: {
SEL v = ((SEL (*)(id, SEL))(void *) objc_msgSend)((id)model, propertyMeta->_getter);
value = v ? NSStringFromSelector(v) : nil;
} break;
default: break;
}
}
if (!value) return;
if (propertyMeta->_mappedToKeyPath) {
NSMutableDictionary *superDic = dic;
NSMutableDictionary *subDic = nil;
for (NSUInteger i = 0, max = propertyMeta->_mappedToKeyPath.count; i < max; i++) {
NSString *key = propertyMeta->_mappedToKeyPath[i];
if (i + 1 == max) { // end
if (!superDic[key]) superDic[key] = value;
break;
}
subDic = superDic[key];
if (subDic) {
if ([subDic isKindOfClass:[NSDictionary class]]) {
subDic = subDic.mutableCopy;
superDic[key] = subDic;
} else {
break;
}
} else {
subDic = [NSMutableDictionary new];
superDic[key] = subDic;
}
superDic = subDic;
subDic = nil;
}
} else {
if (!dic[propertyMeta->_mappedToKey]) {
dic[propertyMeta->_mappedToKey] = value;
}
}
}];
if (modelMeta->_hasCustomTransformToDictionary) {
BOOL suc = [((id<YYModel>)model) modelCustomTransformToDictionary:dic];
if (!suc) return nil;
}
return result;
}
