YYModel源代码分析（三）NSObject+YYModel

前言

本文的中文注释代码demo更新在我的github上。

上篇 YYModel源代码分析（二）YYClassInfo
主要分析了YYClassInfo文件。本篇会主要集中在NSObject+YYModel文件上。文章内容会包含一些与JSONModel的比较，想了解JSONModel，可以参考JSONModel源代码解析。

主体分层

NSObject+YYModel主要分为以下几个部分：

• 内部使用的C函数部分
• @interface _YYModelPropertyMeta : NSObject
• @interface _YYModelMeta : NSObject
• @interface NSObject (YYModel) : NSObject
• @interface NSArray (YYModel) : NSObject
• @interface NSDictionary (YYModel) : NSObject
• @protocol YYModel <NSObject>:接口YYModel

由于代码较多，所以会挑重点的部分进行介绍。

NSObject+YYModel源代码

@interface _YYModelPropertyMeta : NSObject

声明

/// A property info in object model.// model property的进一步分装@interface _YYModelPropertyMeta : NSObject {    @package    NSString *_name;             ///< property's name                   //property名    YYEncodingType _type;        ///< property's type                   //property的encode解析值    YYEncodingNSType _nsType;    ///< property's Foundation type        //property的foundation类型    BOOL _isCNumber;             ///< is c number type                  //是不是c语言的数字    Class _cls;                  ///< property's class, or nil          //property的class    Class _genericCls;           ///< container's generic class, or nil if threr's no generic class     //property内包含的类class    SEL _getter;                 ///< getter, or nil if the instances cannot respond        //property getter方法    SEL _setter;                 ///< setter, or nil if the instances cannot respond        //property setter方法    BOOL _isKVCCompatible;       ///< YES if it can access with key-value coding            //是否可以使用KVC    BOOL _isStructAvailableForKeyedArchiver; ///< YES if the struct can encoded with keyed archiver/unarchiver      //是否是struct并且可以archiver/unarchiver    BOOL _hasCustomClassFromDictionary; ///< class/generic class implements +modelCustomClassForDictionary:     //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;      ///< the key mapped to                                     //property本地的key mapper的key    NSArray *_mappedToKeyPath;   ///< the key path mapped to (nil if the name is not key path)  //property本地的key mapper的key path列表    NSArray *_mappedToKeyArray;  ///< the key(NSString) or keyPath(NSArray) array (nil if not mapped to multiple keys) /property本地的key mapper的key列表    YYClassPropertyInfo *_info;  ///< property's info                                   //property的YYClassPropertyInfo info    _YYModelPropertyMeta *_next; ///< next meta if there are multiple properties mapped to the same key.      //同个key的多个property的映射next指针}@end

其中需要理解一下的包括：
1._hasCustomClassFromDictionary就是判断是否有本地的不同class的映射
如下例子，当dictionary包含不同的值的时候，映射的model类型不同

@implementation YYBaseUser+ (Class)modelCustomClassForDictionary:(NSDictionary*)dictionary {    if (dictionary[@"localName"]) {        return [YYLocalUser class];    } else if (dictionary[@"remoteName"]) {        return [YYRemoteUser class];    }    return [YYBaseUser class];}

2.keyMapper相关内容
如下例子，dictionary中不同的key，对应的model的property有一个映射关系
其中对于包含”.”的映射，则是一种多层的映射关系

+ (NSDictionary *)modelCustomPropertyMapper {    return @{ @"name" : @"n",              @"count" : @"ext.c",              @"desc1" : @"ext.d", // mapped to same key path              @"desc2" : @"ext.d", // mapped to same key path              @"desc3" : @"ext.d.e",              @"desc4" : @".ext",              @"modelID" : @[@"ID", @"Id", @"id", @"ext.id"]};}

3._YYModelPropertyMeta *_next同一个key的下一个meta解析类型
因为有了key mapper，所以会出现同一个mapper的key值，可能会一对多个model的property值，这边设计了一个_next指针进行链接

4.Class _genericCls包含的类型
如下例子，property会有NSArray\NSDictionary\NSSet类型，内部的类型就通过该参数表示

@interface YYTestCustomClassModel : NSObject@property (nonatomic, strong) NSArray *users;@property (nonatomic, strong) NSDictionary *userDict;@property (nonatomic, strong) NSSet *userSet;@end+ (NSDictionary *)modelContainerPropertyGenericClass {    return @{@"users" : YYBaseUser.class,             @"userDict" : YYBaseUser.class,             @"userSet" : YYBaseUser.class};}

实现

//通过YYClassInfo，YYClassPropertyInfo，Class对象解析成_YYModelPropertyMeta+ (instancetype)metaWithClassInfo:(YYClassInfo *)classInfo propertyInfo:(YYClassPropertyInfo *)propertyInfo generic:(Class)generic {    // support pseudo generic class with protocol name    // 这边也考虑了，某些类型写在protocol中，包含在<>中，和JSONModel一样进行一下protocol的类型判断    // 比如NSArray<TestObject> xxx    if (!generic && propertyInfo.protocols) {        for (NSString *protocol in propertyInfo.protocols) {            Class cls = objc_getClass(protocol.UTF8String);            if (cls) {                generic = cls;                break;            }        }    }    //构造_YYModelPropertyMeta对象    _YYModelPropertyMeta *meta = [self new];    meta->_name = propertyInfo.name;                //设置名    meta->_type = propertyInfo.type;                //设置encode type    meta->_info = propertyInfo;                     //设置YYClassPropertyInfo    meta->_genericCls = generic;                    //设置可能有的包含类    if ((meta->_type & YYEncodingTypeMask) == YYEncodingTypeObject) {   //如果是OC对象，则判断是不是标准oc foundation类型        meta->_nsType = YYClassGetNSType(propertyInfo.cls);    } else {        meta->_isCNumber = YYEncodingTypeIsCNumber(meta->_type);        //判断是否是c 数字    }    if ((meta->_type & YYEncodingTypeMask) == YYEncodingTypeStruct) {       //判断和是否是struct        /*         It seems that NSKeyedUnarchiver cannot decode NSValue except these structs:         */        //NSKeyedUnarchiver只可以解析以下的struct        static NSSet *types = nil;        static dispatch_once_t onceToken;        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;        });        if ([types containsObject:propertyInfo.typeEncoding]) {            meta->_isStructAvailableForKeyedArchiver = YES;        }    }    meta->_cls = propertyInfo.cls;      //设置类    if (generic) {      //如果是包含类的话，用包含类去判断是否需要类型转换        meta->_hasCustomClassFromDictionary = [generic respondsToSelector:@selector(modelCustomClassForDictionary:)];    } else if (meta->_cls && meta->_nsType == YYEncodingTypeNSUnknown) {        //如果是其它oc类型，用类型去判断是否需要类型转换        meta->_hasCustomClassFromDictionary = [meta->_cls respondsToSelector:@selector(modelCustomClassForDictionary:)];    }    //设置getter方法    if (propertyInfo.getter) {        if ([classInfo.cls instancesRespondToSelector:propertyInfo.getter]) {            meta->_getter = propertyInfo.getter;        }    }    //设置setter方法    if (propertyInfo.setter) {        if ([classInfo.cls instancesRespondToSelector:propertyInfo.setter]) {            meta->_setter = propertyInfo.setter;        }    }    //如果包含getter和setter方法    if (meta->_getter && meta->_setter) {        /*         KVC invalid type:         long double         pointer (such as SEL/CoreFoundation object)         */        //以下代表可以使用kvc进行附值        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;}

实现部分还是容易理解，主要还是通过YYClassInfo，YYClassPropertyInfo，Class对象解析成_YYModelPropertyMeta。

@interface _YYModelMeta : NSObject

声明

/// A class info in object model.// model class的进一层封装@interface _YYModelMeta : NSObject {    @package    YYClassInfo *_classInfo;            //YYClassInfo类型    /// Key:mapped key and key path, Value:_YYModelPropertyMeta.    NSDictionary *_mapper;              //key mapper的值，key是mapped key and key path，Value是_YYModelPropertyMeta类型    /// Array<_YYModelPropertyMeta>, all property meta of this model.    NSArray *_allPropertyMetas;         //所有的_YYModelPropertyMeta列表    /// Array<_YYModelPropertyMeta>, property meta which is mapped to a key path.    NSArray *_keyPathPropertyMetas;     //所有的路径映射property缓存    /// Array<_YYModelPropertyMeta>, property meta which is mapped to multi keys.    NSArray *_multiKeysPropertyMetas;   //所有的多层映射property缓存    /// The number of mapped key (and key path), same to _mapper.count.    NSUInteger _keyMappedCount;         //key mapper数量    /// Model class type.    YYEncodingNSType _nsType;           //model class的oc类型    BOOL _hasCustomWillTransformFromDictionary;     //是否包含本地的某些值进行替换    BOOL _hasCustomTransformFromDictionary;         //是否有本地的值的类型判断    BOOL _hasCustomTransformToDictionary;           //与上个相反，当转成dictionary的时候，转换的方式    BOOL _hasCustomClassFromDictionary;             //是否有本地的类型的转换}@end

其中，需要理解的包括：
1.

NSDictionary *_mapper;NSArray *_allPropertyMetas; NSArray *_keyPathPropertyMetas; NSArray *_multiKeysPropertyMetas;

_mapper是包括了所有class和superclass的property的key value缓存，其中的key是所有已经映射过key name和不需要映射的property name组成。
_allPropertyMetas是所有class和superclass的property解析_YYModelPropertyMeta列表。
_keyPathPropertyMetas是表示映射如果是一个路径比如@"count" : @"ext.c"下的_YYModelPropertyMeta列表。
_multiKeysPropertyMetas是表示映射如果是一个NSArray比如@"modelID" : @[@"ID", @"Id", @"id", @"ext.id"]下的_YYModelPropertyMeta列表。

2.

    BOOL _hasCustomWillTransformFromDictionary;     //是否包含本地的某些值进行替换    BOOL _hasCustomTransformFromDictionary;         //是否有本地的值的类型判断    BOOL _hasCustomTransformToDictionary;           //与上个相反，当转成dictionary的时候，转换的方式    BOOL _hasCustomClassFromDictionary;             //是否有本地的类型的转换

判断方式：

    _hasCustomWillTransformFromDictionary = ([cls instancesRespondToSelector:@selector(modelCustomWillTransformFromDictionary:)]);    _hasCustomTransformFromDictionary = ([cls instancesRespondToSelector:@selector(modelCustomTransformFromDictionary:)]);    _hasCustomTransformToDictionary = ([cls instancesRespondToSelector:@selector(modelCustomTransformToDictionary:)]);    _hasCustomClassFromDictionary = ([cls respondsToSelector:@selector(modelCustomClassForDictionary:)]);

对应的实际例子：

@interface YYTestCustomTransformModel : NSObject@property uint64_t id;@property NSString *content;@property NSDate *time;@end-(NSDictionary *)modelCustomWillTransformFromDictionary:(NSDictionary *)dic{    if (dic) {        NSMutableDictionary *dict = [NSMutableDictionary dictionaryWithDictionary:dic];        if (dict[@"date"]) {            dict[@"time"] = dict[@"date"];        }        return dict;    }    return dic;}- (BOOL)modelCustomTransformFromDictionary:(NSDictionary *)dic {    NSNumber *time = dic[@"time"];    if ([time isKindOfClass:[NSNumber class]] && time.unsignedLongLongValue != 0) {        _time = [NSDate dateWithTimeIntervalSince1970:time.unsignedLongLongValue / 1000.0];        return YES;    } else {        return NO;    }}- (BOOL)modelCustomTransformToDictionary:(NSMutableDictionary *)dic {    if (_time) {        dic[@"time"] = @((uint64_t)(_time.timeIntervalSince1970 * 1000));        return YES;    } else {        return NO;    }}

最后一个在_YYModelPropertyMeta已经提过，这里不再提。

实现

- (instancetype)initWithClass:(Class)cls {    YYClassInfo *classInfo = [YYClassInfo classInfoWithClass:cls];      //构造 YYClassInfo结构体    if (!classInfo) return nil;    self = [super init];    // Get black list    NSSet *blacklist = nil;    if ([cls respondsToSelector:@selector(modelPropertyBlacklist)]) {       //黑名单，不解析的property        NSArray *properties = [(id<YYModel>)cls modelPropertyBlacklist];        if (properties) {            blacklist = [NSSet setWithArray:properties];        }    }    // Get white list    NSSet *whitelist = nil;    if ([cls respondsToSelector:@selector(modelPropertyWhitelist)]) {       //白名单，只解析的property        NSArray *properties = [(id<YYModel>)cls modelPropertyWhitelist];        if (properties) {            whitelist = [NSSet setWithArray:properties];        }    }    // Get container property's generic class    //获得包含的类的类型    NSDictionary *genericMapper = nil;    if ([cls respondsToSelector:@selector(modelContainerPropertyGenericClass)]) {        genericMapper = [(id<YYModel>)cls modelContainerPropertyGenericClass];      //获得包含类映射的dictionary        if (genericMapper) {            NSMutableDictionary *tmp = [NSMutableDictionary new];            [genericMapper enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {        //遍历dictionary                if (![key isKindOfClass:[NSString class]]) return;                Class meta = object_getClass(obj);          //获得映射的类型                if (!meta) return;                          //不是类型返回                if (class_isMetaClass(meta)) {              //如果是meta class的话,直接设置（因为是对象的类类型)                    tmp[key] = obj;                } else if ([obj isKindOfClass:[NSString class]]) {  //如果是string的话，转成class，设置                    Class cls = NSClassFromString(obj);                    if (cls) {                        tmp[key] = cls;                    }                }            }];            genericMapper = tmp;                    //获得包含类的映射dictionary        }    }    // Create all property metas.    NSMutableDictionary *allPropertyMetas = [NSMutableDictionary new];    YYClassInfo *curClassInfo = classInfo;    //递归class和superclass，但忽略nsobject/nsproxy    while (curClassInfo && curClassInfo.superCls != nil) { // recursive parse super class, but ignore root class (NSObject/NSProxy)        //获得class的所有YYClassPropertyInfo缓存        for (YYClassPropertyInfo *propertyInfo in curClassInfo.propertyInfos.allValues) {            if (!propertyInfo.name) continue;            if (blacklist && [blacklist containsObject:propertyInfo.name]) continue;    //跳过黑名单            if (whitelist && ![whitelist containsObject:propertyInfo.name]) continue;   //只判断拍名单            //构造_YYModelPropertyMeta结构体            _YYModelPropertyMeta *meta = [_YYModelPropertyMeta metaWithClassInfo:classInfo                                                                    propertyInfo:propertyInfo                                                                         generic:genericMapper[propertyInfo.name]];            if (!meta || !meta->_name) continue;                        //没有名字跳过            if (!meta->_getter || !meta->_setter) continue;             //没有getter或者setter方法跳过            if (allPropertyMetas[meta->_name]) continue;                //已经解析过的跳过            allPropertyMetas[meta->_name] = meta;                       //将解析通过dictionary缓存        }        curClassInfo = curClassInfo.superClassInfo;                 //递归super class    }    if (allPropertyMetas.count) _allPropertyMetas = allPropertyMetas.allValues.copy;    //复制一份解析出来的所有allPropertyMetas    // create mapper    //开始key mapper映射    NSMutableDictionary *mapper = [NSMutableDictionary new];    NSMutableArray *keyPathPropertyMetas = [NSMutableArray new];    NSMutableArray *multiKeysPropertyMetas = [NSMutableArray new];    //如果有key mapper 映射    if ([cls respondsToSelector:@selector(modelCustomPropertyMapper)]) {        NSDictionary *customMapper = [(id <YYModel>)cls modelCustomPropertyMapper];        [customMapper enumerateKeysAndObjectsUsingBlock:^(NSString *propertyName, NSString *mappedToKey, BOOL *stop) {            _YYModelPropertyMeta *propertyMeta = allPropertyMetas[propertyName];        //找到映射值的_YYModelPropertyMeta            if (!propertyMeta) return;                              //没有直接返回            [allPropertyMetas removeObjectForKey:propertyName];     //有映射所以从原来的列表删除            if ([mappedToKey isKindOfClass:[NSString class]]) {             //如果是NSString映射                if (mappedToKey.length == 0) return;                propertyMeta->_mappedToKey = mappedToKey;               //设置mapper key                NSArray *keyPath = [mappedToKey componentsSeparatedByString:@"."];  //如果是包含"."代表key的路径映射                for (NSString *onePath in keyPath) {                    if (onePath.length == 0) {                        NSMutableArray *tmp = keyPath.mutableCopy;                        [tmp removeObject:@""];                        keyPath = tmp;                        break;                    }                }                if (keyPath.count > 1) {                            //>1说明有路径映射                    propertyMeta->_mappedToKeyPath = keyPath;       //设置_mappedToKeyPath                    [keyPathPropertyMetas addObject:propertyMeta];  //添加路径映射对象                }                propertyMeta->_next = mapper[mappedToKey] ?: nil;   //如果包含上一个同样key值的_YYModelPropertyMeta对象，则设置next指针                mapper[mappedToKey] = propertyMeta;            } else if ([mappedToKey isKindOfClass:[NSArray class]]) {       //如果是nsarray映射                NSMutableArray *mappedToKeyArray = [NSMutableArray new];                for (NSString *oneKey in ((NSArray *)mappedToKey)) {        //多一级nsarray的遍历，内容与nsstring相同                    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;     //多级的映射值会存到_mappedToKeyArray                [multiKeysPropertyMetas addObject:propertyMeta];                propertyMeta->_next = mapper[mappedToKey] ?: nil;   //同样，如果包含上一个同样key值的_YYModelPropertyMeta对象，则设置next指针                mapper[mappedToKey] = propertyMeta;            }        }];    }    //映射完后，遍历所有的allPropertyMetas，设置mapper和next指针    [allPropertyMetas enumerateKeysAndObjectsUsingBlock:^(NSString *name, _YYModelPropertyMeta *propertyMeta, BOOL *stop) {        propertyMeta->_mappedToKey = name;        propertyMeta->_next = mapper[name] ?: nil;        mapper[name] = propertyMeta;    }];    //如果有映射值，则缓存    if (mapper.count) _mapper = mapper;    //如果路径映射值，则缓存    if (keyPathPropertyMetas) _keyPathPropertyMetas = keyPathPropertyMetas;    //如果有多映射值，则缓存    if (multiKeysPropertyMetas) _multiKeysPropertyMetas = multiKeysPropertyMetas;    _classInfo = classInfo;         //设置classinfo    _keyMappedCount = _allPropertyMetas.count;          //设置property数量    _nsType = YYClassGetNSType(cls);            //获得本类的oc foundation类型    _hasCustomWillTransformFromDictionary = ([cls instancesRespondToSelector:@selector(modelCustomWillTransformFromDictionary:)]);    _hasCustomTransformFromDictionary = ([cls instancesRespondToSelector:@selector(modelCustomTransformFromDictionary:)]);    _hasCustomTransformToDictionary = ([cls instancesRespondToSelector:@selector(modelCustomTransformToDictionary:)]);    _hasCustomClassFromDictionary = ([cls respondsToSelector:@selector(modelCustomClassForDictionary:)]);    return self;}/// Returns the cached model class meta//返回缓存的model class meta+ (instancetype)metaWithClass:(Class)cls {    if (!cls) return nil;    static CFMutableDictionaryRef cache;        //class的_YYModelMeta缓存    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) {             //利用        meta = [[_YYModelMeta alloc] initWithClass:cls];    //重新构造 _YYModelMeta缓存        if (meta) {                                         //设置缓存            dispatch_semaphore_wait(lock, DISPATCH_TIME_FOREVER);            CFDictionarySetValue(cache, (__bridge const void *)(cls), (__bridge const void *)(meta));            dispatch_semaphore_signal(lock);        }    }    return meta;}

实现处理了很多key mapper的映射问题，但本身逻辑并不复杂。

解析逻辑

//id json对象转化为 dictioanry的方法+ (NSDictionary *)_yy_dictionaryWithJSON:(id)json {    if (!json || json == (id)kCFNull) return nil;    NSDictionary *dic = nil;    NSData *jsonData = nil;    if ([json isKindOfClass:[NSDictionary class]]) {        dic = json;    } else if ([json isKindOfClass:[NSString class]]) {        jsonData = [(NSString *)json dataUsingEncoding : NSUTF8StringEncoding];    } else if ([json isKindOfClass:[NSData class]]) {        jsonData = json;    }    if (jsonData) {        dic = [NSJSONSerialization JSONObjectWithData:jsonData options:kNilOptions error:NULL];        if (![dic isKindOfClass:[NSDictionary class]]) dic = nil;    }    return dic;}//先转化json对象到dictionary，再调用yy_modelWithDictionary+ (instancetype)yy_modelWithJSON:(id)json {    NSDictionary *dic = [self _yy_dictionaryWithJSON:json];    return [self yy_modelWithDictionary:dic];}//解析model属性并附值+ (instancetype)yy_modelWithDictionary:(NSDictionary *)dictionary {    if (!dictionary || dictionary == (id)kCFNull) return nil;    if (![dictionary isKindOfClass:[NSDictionary class]]) return nil;    Class cls = [self class];    //解析class得到modelmeta对象    _YYModelMeta *modelMeta = [_YYModelMeta metaWithClass:cls];    //本地class类型映射    if (modelMeta->_hasCustomClassFromDictionary) {        cls = [cls modelCustomClassForDictionary:dictionary] ?: cls;    }    NSObject *one = [cls new];    //附值函数    if ([one yy_modelSetWithDictionary:dictionary]) return one;    return nil;}//附值函数- (BOOL)yy_modelSetWithDictionary:(NSDictionary *)dic {    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;    //本地dictionary值替换    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);    //遍历dictioanry并附值    if (modelMeta->_keyMappedCount >= CFDictionaryGetCount((CFDictionaryRef)dic)) {        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 {        CFArrayApplyFunction((CFArrayRef)modelMeta->_allPropertyMetas,                             CFRangeMake(0, modelMeta->_keyMappedCount),                             ModelSetWithPropertyMetaArrayFunction,                             &context);    }    //本地property验证    if (modelMeta->_hasCustomTransformFromDictionary) {        return [((id<YYModel>)self) modelCustomTransformFromDictionary:dic];    }    return YES;}

附值这块，就只取ModelSetWithDictionaryFunction设置

static void ModelSetWithDictionaryFunction(const void *_key, const void *_value, void *_context) {    ModelSetContext *context = _context;    __unsafe_unretained _YYModelMeta *meta = (__bridge _YYModelMeta *)(context->modelMeta); //取_YYModelMeta    __unsafe_unretained _YYModelPropertyMeta *propertyMeta = [meta->_mapper objectForKey:(__bridge id)(_key)];  //取_YYModelPropertyMeta    __unsafe_unretained id model = (__bridge id)(context->model);    while (propertyMeta) {          //循环遍历propertyMeta        if (propertyMeta->_setter) {            ModelSetValueForProperty(model, (__bridge __unsafe_unretained id)_value, propertyMeta); //设置值        }        propertyMeta = propertyMeta->_next;    };}

而ModelSetValueForProperty的设置函数，就是根据不同类型，去调用msgSend调用相应的meta->_setter方法，进行附值，代码较长，这里也不贴了。

至此，整个YYModel的解析就完成了。

总结

YYModel在整体的解析过程中，分三步：
1. 先将Class的Method，Property，Ivar分别解析缓存，构成Class的缓存
2. 构建_YYModelPropertyMeta缓存Property结构体，再_YYModelMeta缓存_YYModelPropertyMeta结构。
3.根据解析出来的_YYModelPropertyMeta与相应的YYEncodingType等属性，进行相应值的设置

JSONModel与YYModel对比

对比 JSONModel YYModel 解析方式 只解析property attribute encode string 解析Class Method,Property,Ivar缓存，再构造_YYModelPropertyMeta与_YYModelMeta 附值方式 KVC 先解析出property的类型，使用msgSend调用meta->setter方法分类型附值 缓存方式 AssociatedObject CFMutableDictionaryRef 包含类型方式 定义同名protocol，声明protocol 不仅可以声明protocol定义，还可以实现modelContainerPropertyGenericClass接口 映射值为路径解析 无 有 model类型转换 无 有 懒加载 有 无 是否可以缺省 通过protocol optional 黑名单、白名单

参考资料

简书地址
1.JSONModel源代码解析
2.郑钦洪_：YYModel 源码历险记