YYModel现在项目用来自动解析json数据转model，简单记录下原理。
第一步是收集目标类的类名、元类、ivarlist、methodlist、propertylist、再递归的收集
- (instancetype)initWithClass:(Class)cls {
if (!cls) return nil;
self = [super init];
_cls = cls;
_superCls = class_getSuperclass(cls);
_isMeta = class_isMetaClass(cls);
if (!_isMeta) {
_metaCls = objc_getMetaClass(class_getName(cls));
}
_name = NSStringFromClass(cls);
[self _update];
_superClassInfo = [self.class classInfoWithClass:_superCls];
return self;
}
- (void)_update {
_ivarInfos = nil;
_methodInfos = nil;
_propertyInfos = nil;
Class cls = self.cls;
unsigned int methodCount = 0;
Method *methods = class_copyMethodList(cls, &methodCount);
if (methods) {
NSMutableDictionary *methodInfos = [NSMutableDictionary new];
_methodInfos = methodInfos;
for (unsigned int i = 0; i < methodCount; i++) {
BDWTClassMethodInfo *info = [[BDWTClassMethodInfo alloc] initWithMethod:methods[i]];
if (info.name) methodInfos[info.name] = info;
}
free(methods);
}
unsigned int propertyCount = 0;
objc_property_t *properties = class_copyPropertyList(cls, &propertyCount);
if (properties) {
NSMutableDictionary *propertyInfos = [NSMutableDictionary new];
_propertyInfos = propertyInfos;
for (unsigned int i = 0; i < propertyCount; i++) {
BDWTClassPropertyInfo *info = [[BDWTClassPropertyInfo alloc] initWithProperty:properties[i]];
if (info.name) propertyInfos[info.name] = info;
}
free(properties);
}
unsigned int ivarCount = 0;
Ivar *ivars = class_copyIvarList(cls, &ivarCount);
if (ivars) {
NSMutableDictionary *ivarInfos = [NSMutableDictionary new];
_ivarInfos = ivarInfos;
for (unsigned int i = 0; i < ivarCount; i++) {
BDWTClassIvarInfo *info = [[BDWTClassIvarInfo alloc] initWithIvar:ivars[i]];
if (info.name) ivarInfos[info.name] = info;
}
free(ivars);
}
_needUpdate = NO;
}接下来处理关心的数据写回model。
+ (instancetype)yy_modelWithDictionary:(NSDictionary *)dictionary {
if (!dictionary || dictionary == (id)kCFNull) return nil;
if (![dictionary isKindOfClass:[NSDictionary class]]) return nil;
Class cls = [self class];
_yyModelMeta *modelMeta = [_yyModelMeta metaWithClass:cls];
if (modelMeta->_hasCustomClassFromDictionary) {
cls = [cls modelCustomClassForDictionary:dictionary] ?: cls;
}
NSObject *one = [cls new];
if ([one yy_modelSetWithDictionary:dictionary]) return one;
return nil;
}遍历dic，收集我们关心的属性数据
- (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;
ModelSetContext context = {0};
context.modelMeta = (__bridge void *)(modelMeta);
context.model = (__bridge void *)(self);
context.dictionary = (__bridge void *)(dic);
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);
}
} else {
CFArrayApplyFunction((CFArrayRef)modelMeta->_allPropertyMetas,
CFRangeMake(0, modelMeta->_keyMappedCount),
ModelSetWithPropertyMetaArrayFunction,
&context);
}
if (modelMeta->_hasCustomTransformFromDictionary) {
return [((id<yyModel>)self) modelCustomTransformFromDictionary:dic];
}
return YES;
}遍历属性数组，到dic里面取数据
/**
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 _BDWTModelPropertyMeta *propertyMeta = (__bridge _yyModelPropertyMeta *)(_propertyMeta);
if (!propertyMeta->_setter) return;
id value = nil;
if (propertyMeta->_mappedToKeyPath) {
value = (yyValueForKeyPath(dictionary, propertyMeta->_mappedToKeyPath));
} else {
value = [dictionary objectForKey:propertyMeta->_mappedToKey];
}
if (value) {
__unsafe_unretained id model = (__bridge id)(context->model);
ModelSetValueForProperty(model, value, propertyMeta);
}
}收集到数据通过((void (*)(id, SEL, id))(void *) objc_msgSend)((id)model, meta->_setter, (id)nil);设置对象属性。
/**
Set value to model with a property meta.
@discussion Caller should hold strong reference to the parameters before this function returns.
@param model Should not be nil.
@param value Should not be nil, but can be NSNull.
@param meta Should not be nil, and meta->_setter should not be nil.
*/
static void ModelSetValueForProperty(__unsafe_unretained id model,
__unsafe_unretained id value,
__unsafe_unretained _yyModelPropertyMeta *meta) {
if (meta->_isCNumber) {
NSNumber *num = yyNSNumberCreateFromID(value);
ModelSetNumberToProperty(model, num, meta);
if (num) [num class]; // hold the number
} else if (meta->_nsType) {
if (value == (id)kCFNull) {
((void (*)(id, SEL, id))(void *) objc_msgSend)((id)model, meta->_setter, (id)nil);
}
}
case yyEncodingTypeNSArray:
case yyEncodingTypeNSMutableArray: {
if (meta->_genericCls) {
NSArray *valueArr = nil;
if ([value isKindOfClass:[NSArray class]]) valueArr = value;
else if ([value isKindOfClass:[NSSet class]]) valueArr = ((NSSet *)value).allObjects;
if (valueArr) {
NSMutableArray *objectArr = [NSMutableArray new];
for (id one in valueArr) {
if ([one isKindOfClass:meta->_genericCls]) {
[objectArr addObject:one];
} else if ([one isKindOfClass:[NSDictionary class]]) {
Class cls = meta->_genericCls;
if (meta->_hasCustomClassFromDictionary) {
cls = [cls modelCustomClassForDictionary:one];
if (!cls) cls = meta->_genericCls; // for xcode code coverage
}
NSObject *newOne = [cls new];
[newOne yy_modelSetWithDictionary:one];
if (newOne) [objectArr addObject:newOne];
}
}
((void (*)(id, SEL, id))(void *) objc_msgSend)((id)model, meta->_setter, objectArr);
}
} else {
if ([value isKindOfClass:[NSArray class]]) {
if (meta->_nsType == BDWTEncodingTypeNSArray) {
((void (*)(id, SEL, id))(void *) objc_msgSend)((id)model, meta->_setter, value);
} else {
((void (*)(id, SEL, id))(void *) objc_msgSend)((id)model,
meta->_setter,
((NSArray *)value).mutableCopy);
}
} else if ([value isKindOfClass:[NSSet class]]) {
if (meta->_nsType == BDWTEncodingTypeNSArray) {
((void (*)(id, SEL, id))(void *) objc_msgSend)((id)model, meta->_setter, ((NSSet *)value).allObjects);
} else {
((void (*)(id, SEL, id))(void *) objc_msgSend)((id)model,
meta->_setter,
((NSSet *)value).allObjects.mutableCopy);
}
}
}
} break;
case BDWTEncodingTypeNSDictionary:
case BDWTEncodingTypeNSMutableDictionary: {
if ([value isKindOfClass:[NSDictionary class]]) {
if (meta->_genericCls) {
NSMutableDictionary *dic = [NSMutableDictionary new];
[((NSDictionary *)value) enumerateKeysAndObjectsUsingBlock:^(NSString *oneKey, id oneValue, BOOL *stop) {
if ([oneValue isKindOfClass:[NSDictionary class]]) {
Class cls = meta->_genericCls;
if (meta->_hasCustomClassFromDictionary) {
cls = [cls modelCustomClassForDictionary:oneValue];
if (!cls) cls = meta->_genericCls; // for xcode code coverage
}
NSObject *newOne = [cls new];
[newOne yy_modelSetWithDictionary:(id)oneValue];
if (newOne) dic[oneKey] = newOne;
}
}];
((void (*)(id, SEL, id))(void *) objc_msgSend)((id)model, meta->_setter, dic);
} else {
if (meta->_nsType == yyEncodingTypeNSDictionary) {
((void (*)(id, SEL, id))(void *) objc_msgSend)((id)model, meta->_setter, value);
} else {
((void (*)(id, SEL, id))(void *) objc_msgSend)((id)model,
meta->_setter,
((NSDictionary *)value).mutableCopy);
}
}
}
} break;
。。。。。。。。。。。。。。。。。。。。。。
值得注意的点：
1.开源框架使用了许多CF对象和桥接
2.有使用CF对象维护了一套缓存机制
3.大量的使用了高效的自旋锁
4.重定向属性名关联待解析数据
5.容器属性可以关联内部数据，递归的进行解析