[iOS] Json反序列化的幾種方式 - KVC / JSONModel / Mantle / MJExtension / YYModel

節(jié)前鵬鵬讓我看json反序列化為model，主要是很多場景都是從網(wǎng)絡(luò)拿到j(luò)son萎战，然后要轉(zhuǎn)成數(shù)據(jù)model单山，自己寫的話就很費(fèi)事兒，但講真節(jié)前一天完全沒心情寫代碼0.0 于是假期來補(bǔ)吧~

主要的幾種方式為：KVC具滴、Mantle、MJExtension师倔、JSONModel构韵、YYmodel。

以下為示例json文件~

// sample.json文件
{
    "name": "ying", 
    "age": "25", 
    "school": {
        "name": "SJTU", 
        "location": "Shanghai"
    }
}

1. KVC

setValuesForKeysWithDictionary可以直接通過dictionary把key-value設(shè)置給object趋艘，key只要和property名字一樣就可以啦~

下面是model類：

#import <Foundation/Foundation.h>

#import "JsonSchool.h"

NS_ASSUME_NONNULL_BEGIN

@interface JsonPersion : NSObject

@property (nonatomic, copy) NSString *name;
@property (nonatomic, copy) NSString *age;
@property (nonatomic, strong) JsonSchool *school;

@end

NS_ASSUME_NONNULL_END

=======================

#import "JsonPersion.h"

@implementation JsonPersion

- (NSString *)description {
    return [NSString stringWithFormat:@"name:%@, age:%@, school:%@", self.name, self.age, self.school] ;
}

@end

=======================

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@interface JsonSchool : NSObject

@property (nonatomic, copy) NSString *name;
@property (nonatomic, copy) NSString *location;

@end

NS_ASSUME_NONNULL_END

=======================

#import "JsonSchool.h"

@implementation JsonSchool

- (NSString *)description {
    return [NSString stringWithFormat:@"name:%@, location:%@", self.name, self.location] ;
}

@end

解析的時只要：

#import "JsonParserViewController.h"
#import "JsonPersion.h"

@interface JsonParserViewController ()

@end

@implementation JsonParserViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    NSDictionary *dict = [self readLocalFileWithName:@"sample"];
    JsonPersion *p1 = [[JsonPersion alloc] init];
    [p1 setValuesForKeysWithDictionary:dict];
    NSLog(@"p1: %@", p1);
}

- (NSDictionary *)readLocalFileWithName:(NSString *)name
{
    NSString *path = [[NSBundle mainBundle] pathForResource:name ofType:@"json"];
    NSData *data = [[NSData alloc] initWithContentsOfFile:path];
    
    return [NSJSONSerialization JSONObjectWithData:data
                                           options:kNilOptions
                                             error:nil];
}

@end

輸出就是醬紫的：

2020-01-25 14:24:02.915340+0800 Example1[4737:869487] p1: name:ying, age:25, school:{
    location = Shanghai;
    name = SJTU;
}

注意key和property必須一一對應(yīng)疲恢，或者key比property少，如果dict里面的key不是property會crash的吼瓷胧，而且key的名字必須和property的一致显拳，因?yàn)槠鋵?shí)setValuesForKeysWithDictionary就是依次調(diào)用setValueForKeyPath吧~

2. Mantle

git: https://github.com/Mantle/Mantle (使用的時候pod即可)

Mantle可以輕松把JSON數(shù)據(jù)、字典（Dictionary）和模型（即Objective對象）之間的相互轉(zhuǎn)換搓萧，支持自定義映射杂数，并且內(nèi)置實(shí)現(xiàn)了NSCoding和NSCoping，大大簡化歸檔操作瘸洛。

對于mantle而言最重要的就是實(shí)現(xiàn)JSONKeyPathsByPropertyKey耍休，以及千萬記得任何一個model類都要繼承MTLModel <MTLJSONSerializing>：

#import <Foundation/Foundation.h>
#import <Mantle/Mantle.h>

NS_ASSUME_NONNULL_BEGIN

@interface JsonSchoolMantle : MTLModel <MTLJSONSerializing>

@property (nonatomic, copy) NSString *name;
@property (nonatomic, copy) NSString *location;

@end

@interface JsonPersonMantle : MTLModel <MTLJSONSerializing>

@property (nonatomic, copy) NSString *name;
@property (nonatomic, copy) NSString *age;
@property (nonatomic, strong) JsonSchoolMantle *school;

@end

NS_ASSUME_NONNULL_END

=====================

#import "JsonPersonMantle.h"

@implementation JsonSchoolMantle

+ (NSDictionary *)JSONKeyPathsByPropertyKey {
    return @{
        @"name" : @"name",
        @"location" : @"location"
    };
}

- (NSString *)description {
    return [NSString stringWithFormat:@"name:%@, location:%@", self.name, self.location] ;
}

@end

@implementation JsonPersonMantle

+ (NSDictionary *)JSONKeyPathsByPropertyKey { 
    return @{
        @"name":@"name",
        @"age":@"age",
        @"school":@"school"
    };
}

+ (NSValueTransformer *)schoolJSONTransformer {
    return [MTLJSONAdapter dictionaryTransformerWithModelClass:[JsonSchoolMantle class]];
}

- (NSString *)description {
    return [NSString stringWithFormat:@"name:%@, age:%@, school:%@", self.name, self.age, self.school] ;
}

@end

使用的時候只要：

NSDictionary *dict = [self readLocalFileWithName:@"sample"];
JsonPersonMantle *p1 = [MTLJSONAdapter modelOfClass:[JsonPersonMantle class] fromJSONDictionary:dict error:nil];
NSLog(@"p1: %@", p1);

輸出：
2020-01-26 09:35:13.154737+0800 Example1[6023:1175811] p1: name:ying, age:25, school:name:SJTU, location:shanghai

注意使用的時候屬性名JSONTransformer其實(shí)就是一個轉(zhuǎn)換器，因?yàn)橛械臅r候?qū)傩允荖SDate這種货矮，但是json里面就是一個string羊精，需要轉(zhuǎn)換成相應(yīng)的屬性類型。本例里面的school也是囚玫，由于是一個嵌套結(jié)構(gòu)喧锦，school也是一個小json，所以它也需要從一個小json轉(zhuǎn)換成一個model抓督，也需要一個transformer燃少。

由于JSONKeyPathsByPropertyKey可以自定義屬性以及json中字段的對應(yīng)關(guān)系，所以Mantle比KVC好的一點(diǎn)就是可以property和json字段不一定必須名字一致哈铃在。

3. JSONModel

git: https://github.com/jsonmodel/jsonmodel

JSONModel和KVC類似阵具，它也不需要.m文件里面干點(diǎn)兒啥碍遍，只要一句話就能搞成model。但是model類需要繼承JSONModel哦~

#import <Foundation/Foundation.h>
@import JSONModel;

NS_ASSUME_NONNULL_BEGIN

@interface JsonSchoolModel : JSONModel

@property (nonatomic, copy) NSString *name;
@property (nonatomic, copy) NSString *location;

@end

@interface JsonPersonModel : JSONModel

@property (nonatomic, copy) NSString *name;
@property (nonatomic, copy) NSString *age;
@property (nonatomic, strong) JsonSchoolModel *school;

@end

NS_ASSUME_NONNULL_END

====================

#import "JsonPersonModel.h"

@implementation JsonSchoolModel

- (NSString *)description {
    return [NSString stringWithFormat:@"name:%@, location:%@", self.name, self.location] ;
}

@end

@implementation JsonPersonModel

- (NSString *)description {
    return [NSString stringWithFormat:@"name:%@, age:%@, school:%@", self.name, self.age, self.school] ;
}

@end

使用的時候：

NSDictionary *dict = [self readLocalFileWithName:@"sample"];
JsonPersonModel *p1 = [[JsonPersonModel alloc] initWithDictionary:dict error:NULL];
NSLog(@"p1: %@", p1);

輸出：
2020-01-26 09:59:06.664587+0800 Example1[6093:1188064] p1: name:ying, age:25, school:name:SJTU, location:shanghai

如果key和property名字不一樣呢阳液？

可以使用keyMapper來定義如何map怕敬，例如下面的官方例子就是把property名orderId對應(yīng)到j(luò)son里面的order_id，自動在中間加一個下劃線來對應(yīng)：

{
    "order_id": 104,
    "order_product": "Product #1",
    "order_price": 12.95
}
@interface OrderModel : JSONModel
@property (nonatomic) NSInteger orderId;
@property (nonatomic) NSString *orderProduct;
@property (nonatomic) float orderPrice;
@end

@implementation OrderModel

+ (JSONKeyMapper *)keyMapper
{
    return [JSONKeyMapper mapperForSnakeCase];
}

@end

4. MJExtension

git：https://github.com/CoderMJLee/MJExtension

MJExtension作為網(wǎng)評最好的一款converter帘皿，它和JSONModel類似东跪，無需.m文件支持，甚至你的model類都不需要繼承JSONModel鹰溜，只要用正常的model虽填，然后convert的時候用mj_objectWithKeyValues即可。

所以舉例里面的model用KVC里面即可曹动，轉(zhuǎn)換用以下代碼：

#import <MJExtension/MJExtension.h>

NSDictionary *dict = [self readLocalFileWithName:@"sample"];
JsonPersion *p1 = [JsonPersion mj_objectWithKeyValues:dict];
NSLog(@"p1: %@", p1);

輸出：
2020-01-26 12:02:49.662849+0800 Example1[6285:1246846] p1: name:ying, age:25, school:name:SJTU, location:shanghai

如果key和property名字不一致斋日，例如將name屬性名改成name2：

NSDictionary *dict = [self readLocalFileWithName:@"sample"];
[JsonPersion mj_setupReplacedKeyFromPropertyName:^NSDictionary *{
    return @{@"name2":@"name"};
}];
JsonPersion *p1 = [JsonPersion mj_objectWithKeyValues:dict];
NSLog(@"p1: %@", p1);

輸出：
2020-01-26 12:14:30.028732+0800 Example1[6307:1251963] p1: name2:ying, age:25, school:name:SJTU, location:shanghai

如果字段是NSDate，但是json里面是string墓陈，也可以通過重寫mj_newValueFromOldValue來實(shí)現(xiàn)轉(zhuǎn)換：

- (id)mj_newValueFromOldValue:(id)oldValue property:(MJProperty *)property{
    if ([property.name isEqualToString:@"birthday"]) {
        if (oldValue) {
            // 格式化時間
            NSDateFormatter* formatter = [[NSDateFormatter alloc] init];
            formatter.timeZone = [NSTimeZone timeZoneWithName:@"shanghai"];
            [formatter setDateStyle:NSDateFormatterMediumStyle];
            [formatter setTimeStyle:NSDateFormatterShortStyle];
            [formatter setDateFormat:@"yyyy年MM月dd日 HH:mm"];
            NSDate* date = [NSDate dateWithTimeIntervalSince1970:[oldValue doubleValue]];
            NSString* dateString = [formatter stringFromDate:date];
            return dateString;
            }
        }
        else {
            return @"日期有誤";
        }
    return oldValue;
}

如果json里面包含array恶守，就是下面醬紫：

[StatusResult mj_setupObjectClassInArray:^NSDictionary *{
    return @{
               @"statuses" : @"Status",
               // @"statuses" : [Status class],
               @"ads" : @"Ad"
               // @"ads" : [Ad class]
           };
}];

5. YYModel

git: https://github.com/ibireme/YYModel

圍觀膜拜大神~ YY系列真的超厲害，它用起來也是不用.m干啥跛蛋，直接用就行，model就用KVC里面的：

#import <NSObject+YYModel.h>

NSDictionary *dict = [self readLocalFileWithName:@"sample"];
JsonPersion *p1 = [JsonPersion modelWithDictionary:dict];
NSLog(@"p1: %@", p1);

輸出：
2020-01-26 12:35:51.598271+0800 Example1[6320:1258252] p1: name:ying, age:25, school:name:SJTU, location:shanghai

注意無論是model沒定義json里面的相應(yīng)property痊硕，或是json里面少了property相應(yīng)的key赊级，都已可以正常編譯過不會crash的哦~

YYModel還可以自動轉(zhuǎn)換數(shù)據(jù)格式吼~ 例如model的property是NSDate，只要json里面的value符合date的格式就會被自動轉(zhuǎn)換吼岔绸。

JSON/Dictionary	Model
NSString	NSNumber,NSURL,SEL,Class
NSNumber	NSString
NSString/NSNumber	C number (BOOL,int,float,NSUInteger,UInt64,...) NaN and Inf will be ignored
NSString	NSDate parsed with these formats: yyyy-MM-dd理逊、yyyy-MM-dd HH:mm:ss、yyyy-MM-dd'T'HH:mm:ss盒揉、yyyy-MM-dd'T'HH:mm:ssZ晋被、EEE MMM dd HH:mm:ss Z yyyy
NSDate	NSString formatted with ISO8601:"YYYY-MM-dd'T'HH:mm:ssZ"
NSValue	struct (CGRect,CGSize,...)
NSNull	nil,0
"no","false",...	@(NO),0
"yes","true",...	@(YES),1

如果property和key不一致可以在model里面覆寫modelCustomPropertyMapper：

// JSON:
{
    "n":"Harry Pottery",
    "p": 256,
    "ext" : {
        "desc" : "A book written by J.K.Rowing."
    },
    "ID" : 100010
}

// Model:
@interface Book : NSObject
@property NSString *name;
@property NSInteger page;
@property NSString *desc;
@property NSString *bookID;
@end
@implementation Book
+ (NSDictionary *)modelCustomPropertyMapper {
    return @{@"name" : @"n",
             @"page" : @"p",
             @"desc" : @"ext.desc",
             @"bookID" : @[@"id",@"ID",@"book_id"]};
}
@end

這里的嵌套可以用 xx.xxx的方式映射為model的一個屬性吼，不用必須讓嵌套的內(nèi)容變成單獨(dú)的model刚盈。這樣的做法mantle之類的也可以哈羡洛。

YYModel也是支持array之類的，感興趣的同學(xué)可以git看一下藕漱，它的文檔也很全欲侮。

6. Comparison

image

上圖是轉(zhuǎn)換同樣次數(shù)所花的時間，可以看出來mantle是最慢的肋联，MJExtension一向是號稱轉(zhuǎn)換效率最高并且最好用的威蕉。YYModel各項(xiàng)指標(biāo)都非常的快，用起來也很方便~

總體而言KVC不適于property和json key名稱不一致橄仍，所以不太好用韧涨；mantle必須要提供key和property的對應(yīng)表牍戚，并且速度較慢；JSONModel也還挺方便的虑粥，但是model需要繼承JSONModel如孝，整體性能不如MJExtension；YYModel比MJExtension要快一些舀奶。使用上講MJExtension暑竟、YYModel其實(shí)方便程度差不多。

但具體使用哪個還是要看情景育勺，比如mantle自動實(shí)現(xiàn)了NSCopying但荤，MJExtension和YYModel并沒有讓原來model繼承神馬，所以沒有對原來的model做默認(rèn)的改變涧至。但性能和方便性而言YYmodel還是很厲害的~

最后推薦一個json直接轉(zhuǎn)成model.h以及.m的工具：http://www.reibang.com/p/7c09fcbb42c3

參考:
http://www.reibang.com/p/d07aaae459d2
性能對比：http://www.reibang.com/p/5d50b7d9abd2
MJExtension用法：http://www.reibang.com/p/1efa3c2ffde3