我应该如何处理来自kvo的NSIndexSet更新表视图？ [英] How should I handle the NSIndexSet from kvo to update a table view?

问题描述

我开始使用键值观察，并且我观察的可变数组给我在更改字典中的NSIndexSets（有序可变对多）。问题是表视图，据我所知我希望我给它NSArrays充分的索引。

I am starting out using key value observing, and the mutable array I'm observing gives me NSIndexSets (Ordered mutable to-many) in the change dictionary. The problem is the table view as far as I know wants me to give it NSArrays full of indexes.

我想到实现一个自定义方法来转换一个到另一个，但是这看起来很慢，我得到的印象是，必须有一个更好的方法来使数据表更改时更新此表视图。

I thought about implementing a custom method to translate one to the other, but this seems slow and I get the impression there must be a better way to make this table view update when the array changes.

这是从UITableViewDataSource的方法。 / p>

This is the method from my UITableViewDataSource.

 -(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{
     switch ([[change valueForKey:NSKeyValueChangeKindKey] unsignedIntValue]) {
         case NSKeyValueChangeSetting:
             NSLog(@"Setting Change");
             break;
         case NSKeyValueChangeInsertion:
             NSLog(@"Insertion Change");

             // How do I fit this:
             NSIndexSet * indexes = [change objectForKey:NSKeyValueChangeIndexesKey];

             // into this:
             [self.tableView insertRowsAtIndexPaths:<#(NSArray *)#> withRowAnimation:<#(UITableViewRowAnimation)#>

             // Or am I just doing it wrong?

             break;
         case NSKeyValueChangeRemoval:
             NSLog(@"Removal Change");
             break;
         case NSKeyValueChangeReplacement:
             NSLog(@"Replacement Change");
             break;
         default:
             break;
     }
 }

推荐答案

看起来很容易。使用 enumerateIndexesUsingBlock： ，并将每个索引粘贴到 NSIndexPath 对象：

This seems easy enough. Enumerate the index set using enumerateIndexesUsingBlock: and stick each index into an NSIndexPath object:

NSMutableArray * paths = [NSMutableArray array];
[indexes enumerateIndexesUsingBlock:^(NSUInteger index, BOOL *stop) {
        [paths addObject:[NSIndexPath indexPathWithIndex:index]];
    }];
[self.tableView insertRowsAtIndexPaths:paths
                      withRowAnimation:<#(UITableViewRowAnimation)#>];

如果你的表视图有部分，这只是一个更复杂，因为你需要正确的节号，并在索引路径中指定它：

If your table view has sections, it's only a bit more complicated, because you'll need to get the correct section number, and specify it in the index path:

NSUInteger sectionAndRow[2] = {sectionNumber, index};
[NSIndexPath indexPathWithIndexes:sectionAndRow
                           length:2];

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