What's This?

CKCollectionViewDataSourceChangesetBuilder is a DSL builder for ComponentKit's CKTransactionalComponentDataSourceChangeset. It is heavily inspired by Masonry, and should allow you to write very readable code for building your changesets.

How Do I Use It?

CKCollectionViewDataSourceChangesetBuilder uses verbs, nouns and prepositions in order to allow you to express your changeset builds in readable English, with just a few exceptions. A few examples will make this clearer:

    [CKCollectionViewDataSourceChangesetBuilder build:^(CKCollectionViewDataSourceChangesetBuilder *builder) {
      builder.insert.section.at.index(0);
      builder.insert.item(@"Foo").at.indexPath([NSIndexPath indexPathForItem:1 inSection:4]);
      builder.remove.section.at.index(1);
      builder.move.section.at.index(0).to.index(4);
    }];

Due to the limited number of keywords, the possible combinations should hopefully be fairly self-explanatory. The builder has been written to throw useful exceptions when the syntax is misused.

CKCollectionViewDataSourceChangesetBuilderTests provides examples of all of the syntax combinations, so please take a look there first.

Helper Macros

• ck_indexPath(ITEM, SECTION) saves constant use of [NSIndexPath indexPathForItem:inSection:].

The following two macros aim to compensate for the lack of default arguments in Objective-C; when moving or removing items we need to reuse the verb item. However, since we have no object to insert the argument must be nil. This wouldn't be nearly as readable. Instead you can use:

• ck_removeItem instead of remove.item(nil).
• ck_moveItem instead of move.item(nil).

Why No Swift?

ComponentKit is written primarily in C++, which means you will usually be using it from within Obj-C++ contexts. Whilst it's possible you could create changesets from Swift contexts, I don't believe this is enough to justify another implementation at this time. Of course, if someone would like to implement it then I'd be happy to receive a PR!

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Have fun!

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