iOS数组、字典与json字符串的转换

/*!
 *  将字典或者数组转化为JSON串
 *
 *  @param theData <#theData description#>
 *
 *  @return <#return value description#>
 */
+ (NSString *)toJSONData:(id)theData{
    NSString * jsonString = @"";
    if (theData != nil) {
        NSData *jsonData = [NSJSONSerialization dataWithJSONObject:theData
                                                           options:NSJSONWritingPrettyPrinted
                                                             error:nil];

        if ([jsonData length] != 0){
            jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
        }
    }
    return jsonString;
}

/*!
 *  将JSON串转化为字典或者数组
 *
 *  @param jsonData <#jsonData description#>
 *
 *  @return <#return value description#>
 */

+ (id)toArrayOrNSDictionary:(NSString *)jsonData{
    if (jsonData != nil) {
        NSData* data = [jsonData dataUsingEncoding:NSUTF8StringEncoding];
        id jsonObject = [NSJSONSerialization JSONObjectWithData:data
                                                        options:NSJSONReadingAllowFragments
                                                          error:nil];

        if (jsonObject != nil){
            return jsonObject;
        }else{
            // 解析错误
            return nil;
        }
    }
    return nil;
}

/*!
 * 对象序列成字典
 *
 * @param obj 需要序列化的对象
 *
 * @return 字典
 */

+ (NSDictionary*)getDictionaryFromObject:(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];
        id value = nil;

        @try {
            NSString *propName = [NSString stringWithUTF8String:property_getName(prop)];
            value = [self getObjectInternal:[obj valueForKey:propName]];
            if(value != nil) {
                [dic setObject:value forKey:propName];
            }
        }
        @catch (NSException *exception) {
            NSLog(@"%@",exception);
        }

    }
    free(props);
    return dic;
}

+ (id)getObjectInternal:(id)obj
{
    if(!obj
       || [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 getDictionaryFromObject:obj];
}