objective-c - 删除用于提交到服务器的 NSDictionary Params 中的重复代码

Question

下面的代码显示了我准备将参数提交到服务器的方式。我有一个 if-else 子句来检查并确定要提交哪些参数，即如果问题 id 存在，则仅提交问题 id，否则提交问题文本和主题 id。

但是，我觉得这有点重复，而且不是最好的编码形式(在我的 POV 中)。如何重构代码以使其更加高效(删除重复)

if(self.question._id || [self.question._id isEqual:[NSNull null]])
{
    //Set up params for submission
    NSDictionary *params= [[NSDictionary alloc] initWithObjectsAndKeys:
                          self.answer.text, @"text",
                          //if question id exists, submit question id only 
                          self.question._id, @"question_id", 
                          shareFb, @"fbShare", 
                          shareTwitter, @"twitterShare",
                          self.question.source,@"questionSource",
                          self.answer.videoId,@"youtube_id",
                          nil
                          ];
}
else
{
    //Set up params for submission
    NSDictionary *params= [[NSDictionary alloc] initWithObjectsAndKeys:
                          self.answer.text, @"text", 
                          //else submit question text and topic id
                          self.question.text, @"question_text",
                          self.question.topic._id, @"topic_id", 
                          shareFb, @"fbShare", 
                          shareTwitter, @"twitterShare",
                          self.question.source,@"questionSource",
                          self.answer.videoId,@"youtube_id",
                          nil
                          ];

Answer 1

使用可变字典，然后您可以添加额外的字段

NSMutableDictionary *params= [[NSMutableDictionary alloc] initWithObjectsAndKeys:
        self.answer.text, @"text",
        //if question id exists, submit question id only 
        self.question._id, @"question_id", 
        shareFb, @"fbShare", 
        shareTwitter, @"twitterShare",
        self.question.source,@"questionSource",
        self.answer.videoId,@"youtube_id",
        nil
        ];

if(!(self.question._id == nil || [self.question._id isEqual:[NSNull null]]))
{
    [params setObject:self.question.text forKey:@"question_text"];
    [params setObject:self.question.topic._id forKey:@"topic_id"];
}

编辑评论 1

如果上面第一条语句中设置的任何参数可能为零，则需要更加小心

NSMutableDictionary *params= [[NSMutableDictionary alloc] init];
if (self.answer.text) {
    [params setObject:self.answer.text forKey:@"text"];
}
•
•  // all the params between self.answer.text and self.answer.videoId
•
if (self.answer.videoId) {
    [params setObject:self.answer.videoId forKey:@"youtube_id"];
}
if(!(self.question._id == nil || [self.question._id isEqual:[NSNull null]]))
    {
        if(self.question.text) {
            [params setObject:self.question.text forKey:@"question_text"];
        }
        if (self.question.topic._id) {
            [params setObject:self.question.topic._id forKey:@"topic_id"];
        }
    }
}

您不能将 nil 对象设置为 key(即 [params setObject:nil forKey:@"key] 将崩溃)