将零个对象插入NSDictionary [英] Inserting nil objects into an NSDictionary

问题描述

如果我们有一个仅需要5个属性中的2个对象的API，而iPhone应用程序不要求它们实例化一个对象，则当在参数NSDicitionary中使用该对象时，该应用程序将崩溃.有人告诉我NSDictionary不会让您分配nil值，因为当它达到nil时，它认为它已经完成了. Objective-C是否可以将非零属性的对象吐出到NSDictionary中?

If we have an API that requires only 2 out of an objects 5 properties and iPhone app doesn't require them to instantiate an object, when the object is used in the params NSDicitionary the app will crash. I was told NSDictionary will not let you assign nil values, as when it reaches nil it thinks its finished. Does objective-c have a way to spit out an objects non-nil properties into an NSDictionary?

示例:

[Drunk alloc] init];
drunk.started_drinking = [NSDate date];
drunk.stopped_drinking (we don't set this because he is still a drunk)
drunk.fat = YES;
drunk.dumb = YES;


parameters:@{

             @"auth_token" :token,
             @"name" : drunk.name, @"date_started" : drunk.started_drinking,
             @"date_stopped" : drunk.stopped_drinking, 
             @"prescribing_doctor" : drunk.fat,
             @"pharmacy" : drunk.dumb

            }

当它进入stopped_drinking属性时，它将崩溃.有关如何处理此问题的任何建议?

This will crash when it gets to the stopped_drinking property. Any suggestions on how to handle this?

推荐答案

这有点长，但是你可以做

It's a bit long winded but you could do

static id ObjectOrNull(id object)
{
  return object ?: [NSNull null];
}

parameters:@{
  @"auth_token"         : ObjectOrNull(token),
  @"name"               : ObjectOrNull(drunk.name),
  @"date_started"       : ObjectOrNull(drunk.started_drinking),
  @"date_stopped"       : ObjectOrNull(drunk.stopped_drinking),
  @"prescribing_doctor" : ObjectOrNull(drunk.fat),
  @"pharmacy"           : ObjectOrNull(drunk.dumb),
}

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