json去空

- (NSMutableDictionary *)dictionaryWithOutNull
{
    NSArray *keysArr = [self allKeys];
    for (NSString *keyStr in keysArr)
    {
        id value = [self objectForKey:keyStr];
        if ([value isKindOfClass:[NSNull class]])
        {
            [self setValue:@"" forKey:keyStr];
        }
        else if ([value isKindOfClass:[NSArray class]])
        {
            NSMutableArray *valueArr = [NSMutableArray arrayWithArray:value];
            
            for (id arrElements in value)
            {
                if ([arrElements isKindOfClass:[NSDictionary class]])
                {
                    NSMutableDictionary *mutaDic = [NSMutableDictionary dictionaryWithDictionary:arrElements];
                    
                    NSInteger index = [valueArr indexOfObject:arrElements];
                    NSDictionary *subDic = (NSDictionary *)[mutaDic dictionaryWithOutNull];
                    [valueArr replaceObjectAtIndex:index withObject:subDic];
                    
                }
            }
            [self setValue:valueArr forKey:keyStr];
            
        }
        else if ([value isKindOfClass:[NSDictionary class]])
        {
            NSMutableDictionary *mutaDic = [NSMutableDictionary dictionaryWithDictionary:value];
            [self setValue:[mutaDic dictionaryWithOutNull] forKey:keyStr];
            
        }
    }
    return self;
}