Mantle For iOS

Mantle可以很方便的去书写一个模型层的代码。

使用它可以很方便的去反序列化JSON或者序列化为JSON(需要在MTLModel子类中实现<MTLJSONSerializing>协议)

使用一个解释器MTLJSONAdapter去转换模型对象。

NSError *error = nil;
MyObject *myObject = [MTLJSONAdapter modelOfClass:MyObject.class fromJSONDictionary:JSONDictionary error:&error]; //把JSONDictionary转换为模型对象NSDictionary *JSONDictionary = [MTLJSONAdapter JSONDictionaryFromModel:myObject]; //将模型对象转为JSON字典

`+JSONKeyPathsByPropertyKey`

这个方法返回一个字典，指定着你的模型对象和JSON中关键字的映射关系。

一个例子：

@interface XYUser : MTLModel@property (readonly, nonatomic, copy) NSString *name;
@property (readonly, nonatomic, strong) NSDate *createdAt;@property (readonly, nonatomic, assign, getter = isMeUser) BOOL meUser;@end@implementation XYUser+ (NSDictionary *)JSONKeyPathsByPropertyKey {return @{@"createdAt": @"created_at", //这里代表createdAt属性映射JSON中的created_at关键字@"meUser": NSNull.null //meUser不会从JSON中反序列化
};
}@end

当我们用字典反序列化的时候

NSDictionary *JSONDictionary = @{@"name": @"john",@"created_at": @"2013/07/02 16:40:00 +0000",@"plan": @"lite"
};XYUser *user = [MTLJSONAdapter modelOfClass:XYUser.class fromJSONDictionary:JSONDictionary error:&error];//user中的name为john createdAt为2013/07/02 16:40:00 +0000 meUser为0 plan将会被忽略

`+JSONTransformerForKey:`

实现这个方法去用一个不一样的类型转换器去转化属性

+ (NSValueTransformer *)JSONTransformerForKey:(NSString *)key {if ([key isEqualToString:@"createdAt"]) {return [NSValueTransformer valueTransformerForName:XYDateValueTransformerName];
}return nil;
}

对于一些值的转换：

+ (NSValueTransformer *)createdAtJSONTransformer {return [MTLValueTransformer reversibleTransformerWithForwardBlock:^(NSString *str) {return [self.dateFormatter dateFromString:str];} reverseBlock:^(NSDate *date) {return [self.dateFormatter stringFromDate:date];
}];
}

`+classForParsingJSONDictionary:`

如果定义了一个类簇，可以实现这个方法去转换。

@interface XYMessage : MTLModel@end@interface XYTextMessage: XYMessage@property (readonly, nonatomic, copy) NSString *body;@end@interface XYPictureMessage : XYMessage@property (readonly, nonatomic, strong) NSURL *imageURL;@end@implementation XYMessage+ (Class)classForParsingJSONDictionary:(NSDictionary *)JSONDictionary {if (JSONDictionary[@"image_url"] != nil) {return XYPictureMessage.class;
}if (JSONDictionary[@"body"] != nil) {return XYTextMessage.class;
}NSAssert(NO, @"No matching class for the JSON dictionary '%@'.", JSONDictionary);return self;
}@end

使用

NSDictionary *textMessage = @{@"id": @1,@"body": @"Hello World!"
};NSDictionary *pictureMessage = @{@"id": @2,@"image_url": @"http://example.com/lolcat.gif"
};XYTextMessage *messageA = [MTLJSONAdapter modelOfClass:XYMessage.class fromJSONDictionary:textMessage error:NULL];XYPictureMessage *messageB = [MTLJSONAdapter modelOfClass:XYMessage.class fromJSONDictionary:pictureMessage error:NULL];