iOS：把对象直接转化成NSDictionary或JSON

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iOS：把对象直接转化成NSDictionary或JSON

Mgen|2013-09-18 10:48|15515次浏览| IOS(296)开发(190)应用(36)对象(1)Dictionary(1) 0

1. 使用

实现的结果就是可以把任何对象转化成字典或者字典对应的JSON。字典的数据就是来自对象的属性名称和属性值。而且是多层的，也就是说如果对象的某个属性值是另一个对象，数组，或者字典，该值都会被转换成另一个字典。

这个类型名称是PrintObject，它的所有方法都是静态的：

  @interface PrintObject : NSObject 
 //通过对象返回一个NSDictionary，键是属性名称，值是属性值。 
 + (NSDictionary*)getObjectData:(id)obj; 
    
 //将getObjectData方法返回的NSDictionary转化成JSON 
 + (NSData*)getJSON:(id)obj options:(NSJSONWritingOptions)options error:(NSError**)error; 
    
 //直接通过NSLog输出getObjectData方法返回的NSDictionary 
 + (void)print:(id)obj; 
    
 @end 
 

举个例子，比如用来保存数据的类型是MyData，这个类型如下定义：

  @interface MyData : NSObject 
 @property (nonatomic, strong) NSString *name; 
 @property (nonatomic, strong) NSString *nullString; 
 @property (nonatomic) int age; 
 @property (nonatomic) BOOL male; 
 @property (nonatomic, strong) MyData *objProp; 
 @property (nonatomic, strong) NSArray *arrProp; 
 @property (nonatomic, strong) NSDictionary *dicProp; 
 @end 
 

然后通过MyData类型创建一个复杂的对象，其中包含非对象属性，对象属性，还有包含对象的数组和字典。代码如下：

  MyData *main = [[MyData alloc] init]; 
 main.name = @ "mgen" ; 
 main.age = 22; 
 MyData *childOfChild = [[MyData alloc] init]; 
 childOfChild.name = @ "child of child" ; 
 childOfChild.age = -443; 
 MyData *child = [[MyData alloc] init]; 
 child.name = @ "child" ; 
 child.arrProp = @[@ "test" , @234, @[@123, @ "array in array" , childOfChild]]; 
 main.objProp = child; 
 main.dicProp = @{@ "中文Key" : @3.444444, @ "object" : childOfChild}; 
 

OK，接着使用PrintObject类型输出这个MyData对象（上面的main变量）的字典：

  NSDictionary *dic = [PrintObject getObjectData:main]; 
 NSLog(@ "%@" , dic); 
 

输出：

  { 
      age = 22; 
      arrProp =  "<null>" ; 
      dicProp =     { 
          object =         { 
              age =  "-443" ; 
              arrProp =  "<null>" ; 
              dicProp =  "<null>" ; 
              male = 0; 
              name =  "child of child" ; 
              nullString =  "<null>" ; 
              objProp =  "<null>" ; 
          }; 
          "\U4e2d\U6587Key" =  "3.444444" ; 
      }; 
      male = 0; 
      name = mgen; 
      nullString =  "<null>" ; 
      objProp =     { 
          age = 0; 
          arrProp =         ( 
              test, 
              234, 
                          ( 
                  123, 
                  "array in array" , 
                                  { 
                      age =  "-443" ; 
                      arrProp =  "<null>" ; 
                      dicProp =  "<null>" ; 
                      male = 0; 
                      name =  "child of child" ; 
                      nullString =  "<null>" ; 
                      objProp =  "<null>" ; 
                  } 
              ) 
          ); 
          dicProp =  "<null>" ; 
          male = 0; 
          name = child; 
          nullString =  "<null>" ; 
          objProp =  "<null>" ; 
      }; 
 } 
 

也可以输出这个对象的JSON数据

  NSData *jsonData = [PrintObject getJSON:main options:NSJSONWritingPrettyPrinted error:nil]; 
 NSString *jsonText = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding]; 
 NSLog(@ "%@" , jsonText); 
 

结果：

  { 
    "arrProp" :  null , 
    "name" :  "mgen" , 
    "age" : 22, 
    "objProp" : { 
      "arrProp" : [ 
        "test" , 
        234, 
        [ 
          123, 
          "array in array" , 
          { 
            "arrProp" :  null , 
            "name" :  "child of child" , 
            "age" : -443, 
            "objProp" :  null , 
            "male" : 0, 
            "nullString" :  null , 
            "dicProp" :  null 
          } 
        ] 
      ], 
      "name" :  "child" , 
      "age" : 0, 
      "objProp" :  null , 
      "male" : 0, 
      "nullString" :  null , 
      "dicProp" :  null 
    }, 
    "male" : 0, 
    "nullString" :  null , 
    "dicProp" : { 
      "中文Key" : 3.444444, 
      "object" : { 
        "arrProp" :  null , 
        "name" :  "child of child" , 
        "age" : -443, 
        "objProp" :  null , 
        "male" : 0, 
        "nullString" :  null , 
        "dicProp" :  null 
      } 
    } 
 } 
 

2. 实现

在实现上，属性的枚举是通过定义在<objc/runtime.h>中的class_copyPropertyList方法实现。其次，属性值的获取是通过KVC中的valueForKey方法，这个方法同时可以将非对象类型（如BOOL, int等）转换成NSNumber。

接着就是对数组，字典和对象类型值的嵌套处理，所有值就可以获取出来了。

至于JSON，如果正确获取了NSDictionary后，直接使用iOS 5后的NSJSONSerialization类型的dataWithJSONObject方法就可以返回包含JSON字符串的NSData对象了。

3. 下载和代码

源代码下载下载页面

注意：链接是微软SkyDrive页面，下载时请用浏览器直接下载，用某些下载工具可能无法下载

源代码环境：Xcode 4.6.3

PrintObject.h

  #import <Foundation/Foundation.h> 
    
 @interface PrintObject : NSObject 
 //通过对象返回一个NSDictionary，键是属性名称，值是属性值。 
 + (NSDictionary*)getObjectData:(id)obj; 
    
 //将getObjectData方法返回的NSDictionary转化成JSON 
 + (NSData*)getJSON:(id)obj options:(NSJSONWritingOptions)options error:(NSError**)error; 
    
 //直接通过NSLog输出getObjectData方法返回的NSDictionary 
 + (void)print:(id)obj; 
    
 @end 
 

PrintObject.m

  #import "PrintObject.h" 
 #import <objc/runtime.h> 
    
 @implementation PrintObject 
    
 + (NSDictionary*)getObjectData:(id)obj 
 { 
      NSMutableDictionary *dic = [NSMutableDictionary dictionary]; 
      unsigned int propsCount; 
      objc_property_t *props = class_copyPropertyList([obj class], &propsCount); 
      for (int i = 0;i < propsCount; i++) 
      { 
          objc_property_t prop = props[i]; 
          
          NSString *propName = [NSString stringWithUTF8String:property_getName(prop)]; 
          id value = [obj valueForKey:propName]; 
          if (value == nil) 
          { 
              value = [NSNull  null ]; 
          } 
          else 
          { 
              value = [self getObjectInternal:value]; 
          } 
          [dic setObject:value forKey:propName]; 
      } 
      return dic; 
 } 
    
 + (void)print:(id)obj 
 { 
      NSLog(@ "%@" , [self getObjectData:obj]); 
 } 
    
    
 + (NSData*)getJSON:(id)obj options:(NSJSONWritingOptions)options error:(NSError**)error 
 { 
      return [NSJSONSerialization dataWithJSONObject:[self getObjectData:obj] options:options error:error]; 
 } 
    
 + (id)getObjectInternal:(id)obj 
 { 
      if ([obj isKindOfClass:[NSString class]] 
         || [obj isKindOfClass:[NSNumber class]] 
         || [obj isKindOfClass:[NSNull class]]) 
      { 
          return obj; 
      } 
      
      if ([obj isKindOfClass:[NSArray class]]) 
      { 
          NSArray *objarr = obj; 
          NSMutableArray *arr = [NSMutableArray arrayWithCapacity:objarr.count]; 
          for (int i = 0;i < objarr.count; i++) 
          { 
              [arr setObject:[self getObjectInternal:[objarr objectAtIndex:i]] atIndexedSubscript:i]; 
          }        
          return arr; 
      } 
      
      if ([obj isKindOfClass:[NSDictionary class]]) 
      { 
          NSDictionary *objdic = obj; 
          NSMutableDictionary *dic = [NSMutableDictionary dictionaryWithCapacity:[objdic count]]; 
          for (NSString *key  in objdic.allKeys) 
          { 
              [dic setObject:[self getObjectInternal:[objdic objectForKey:key]] forKey:key]; 
          }       
          return dic; 
      }   
      return [self getObjectData:obj]; 
 } 
    
 @end 
 