一.调用方法
YYGHUser *model = [YYGHUser yy_modelWithJSON:json];
二.内部实现
+(instancetype)yy_modelWithJSON:(id)json{
//json -> NSDictionary
NSDictionary *dic = [self _yy_dictionaryWithJSON:json];
//NSDictionary -> model
return [self yy_modelWithDictionary:dic];
}
三.json转dic
+(NSDictionary *)_yy_dictionaryWithJSON:(id)json{
//1.如果json为空 return nil
if(!json || json == (id)kCFNull) return nil;
//2
NSDictionary *dic = nil;
NSData *jsonData = nil;
//3.判断json是数据类型
if([json isKindofClass:[NSDictionary class]]){
//如果是NSDictionary类型 把json数据赋值给dic
dic = json;
}else if([json isKindofClass:[NSString class]]){
//如果是NSString类型 把json数据进行NSUTF8StringEncoding编码得到NSData 然后赋值给jsonData
jsonData = [(NSString *)json dataUsingEncoding:NSUTF8StringEncoding];
}else if([json isKindofClass:[NSData class]]){
//如果是NSData类型 直接赋值给jsonData
jsonData = json;
}
if(jsonData){
//如果jsondata数据不为空，调用系统方法NSData -》NSDictionary
dic = [NSJSONSerialization JSONObjectWithData:jsonData options:kNilOptions error:NULL];
//如果得到的dic 类型不是NSDictionary dic = nil
if(![dic isKindOfClass:[NSDictionary class]]) dic = nil;
}
return dic;
}
四.字典转Model
+(instancetype)yy_modelWithDictionary:(NSDictionary *)dictionary{
//判断NSDictionary 不为空
if(!dictionary || dictionary == (id)kCFNull) return nil;
//判断dictionary是否是NSDictionary类型，如果不是NSDictionary类型，return nil
if(![dictionary isKindOfClass:[NSDictioary 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;
}
1，
+(instancetype)metaWithClass:(Class)cls{
if(!cls) return nil;
//这里难道是要做一个缓存区域？
static CFMutableDictionaryRef cache;
static dispatch_once_t onceToken;
static OSSpinLock lock;
dispatch_once(&onceToken,^{
cache = CFDictionaryCreateMutable(CFAllocatorGetDefault(),0,&kCFTypeDictionaryKeyCallBacks,&kCFTypeDictionaryValueCallBacks);
/*! @abstract The default value for anOSSpinLock. @discussion The convention is that unlocked is zero, locked is nonzero. #define OS_SPINLOCK_INIT 0 告诉我们OS_SPINLOCK_INIT 是一个默认值。 不锁定为0 锁定为非0； */
lock = OS_SPINLOCK_INIT;
});
/*! @abstract Locks a spinlock
@discussion
Although the lock operation spins, it employs various strategies
to back off if the lock is held, making it immune to most priority-inversion
livelocks.
*/
OSSpinLockLock(&lock);
//我猜这个是根据key等到value 相当于 [NSDictionary objectForKey:@""];
_YYModelMeta *meta = CFDictionaryGetValue(cache, (__bridge const void *)(cls));
//解锁
OSSpinLockUnlock(&lock);
//如果刚才没有得到数据 生成数据并存入cache
if (!meta) {
//这里是取得类的@property属性或者全部信息，目前还没有研究到
meta = [[_YYModelMeta alloc] initWithClass:cls];
if (meta) {
//存储值，下次可以直接读取，不需要在生成了。
OSSpinLockLock(&lock);
CFDictionarySetValue(cache, (__bridge const void *)(cls), (__bridge const void *)(meta));
OSSpinLockUnlock(&lock);
}
}
return meta;
}
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