Re: Avoid staircasing by creating keyPath dynamically possible?
Re: Avoid staircasing by creating keyPath dynamically possible?
- Subject: Re: Avoid staircasing by creating keyPath dynamically possible?
- From: Ken Thomases <email@hidden>
- Date: Sat, 07 Mar 2015 06:43:07 -0600
On Mar 7, 2015, at 6:34 AM, Diederik Meijer <email@hidden> wrote:
>> On 07 Mar 2015, at 12:36, Ken Thomases <email@hidden> wrote:
>>
>>> On Mar 7, 2015, at 5:02 AM, Diederik Meijer <email@hidden> wrote:
>>>
>>> This is part of XML parsing with NSXMLParser, is there any way to avoid this type of staircasing by constructing a keyPath dynamically?
>>>
>>> if (self.nestingLevel == 1) { [[[self.rootparser nodeTree] lastObject][@"items"] addObject:dict]; }
>>> if (self.nestingLevel == 2) { [[[[self.rootparser nodeTree] lastObject][@"items"] lastObject][@"items"] addObject:dict]; }
>>> if (self.nestingLevel == 3) { [[[[[self.rootparser nodeTree] lastObject][@"items"] lastObject][@"items"] lastObject][@"items"] addObject:dict]; }
>>> if (self.nestingLevel == 4) { [[[[[[self.rootparser nodeTree] lastObject][@"items"] lastObject][@"items"] lastObject][@"items"] lastObject][@"items"] addObject:dict]; }
>>>
>>> As you can see the action is always the same: addObject:dict
>>>
>>> But depending on the level of nesting, lastObject][@"items”] needs to be added multiple times to the self.rootparser’s nodeTree property.
>>>
>>> Is there any way to use a loop that runs for self.nestingLevel times and adds the extra levels to the keyPath just as many times as needed and then use that to access the noteTree at the exact right level?
>>
>> No. Key paths can't index into arrays. However, you can just use a simply for loop. Something like:
>>
>> NSMutableArray* array = [[self.rootparser nodeTree] lastObject][@"items"];
>> for (int i = 1; i < self.nestingLevel; i++)
>> array = array.lastObject[@"items"];
>> [array addObject:dict];
>
>
> Thanks Ken, but this does not seem to traverse down into n nested levels, correct?
It does traverse down. It's just like your code, except generalized.
> The loop goes through the nodeTree's first level children only (pardon the bad semantics here)
Each time through the loop, it reassigns the "array" variable. So, the next time through the loop, it's accessing a deeper level of the tree.
Regards,
Ken
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