NODE

Create a tree from any objects

Why?

Sometimes it is useful to create tree like structures with your objects. A simple example would be a relationship between sections and rows in a table view. Let's say we have an object that represents the table view, and I would like to add some sections and rows. We could naively create a couple of arrays or dictionaries to store that structure, but wouldn't it be easier if the structure is exactly represented as the tree we are trying to build?

- TableView
  - Section[0] 
    - Row[0]
    - Row[1]
  - Section[1]
    - Row[2]

How?

Let's build that tree that we were mentioning in the Why? section. Say we have a TableView, Section and Row classes, all PONSO's. As mentioned in the title, NODE lets you build that structure from any ol' objects.

Row *row0 = [Row new]; 
Row *row1 = [Row new]; 
Section *section0 = [Section new]; 
[section0 node_addChildren:@[row0, row1]];

Row *row2 = [Row new];
Section *section1 = [Section new]; 
[section1 node_addChild:row2];

TableView *tableView = [TableView new];
[tableView node_addChildren:@[section0, section1]];

Now what?

OK, now that you have your tree what can you do with it?

///Gets section0
Section *section = row0.node_parent;

///Gets an array @[row0, row1] 
NSArray *rows = section.node_children; 

///Gets the tableView object
TableView *tableView = [rows[0] node_root];

///Gets an array @[section0, tableView]
NSArray *ancestors = [rows[0] node_ancestors];

///Returns an index path of the row 
NSIndexPath *indexPath = [row[0] node_indexPath];

///Returns row0
Row *row = [section0 node_nodeAtIndexPath:indexPath];

///And last but not least, you can print out the tree
[tableView node_debugDescription];

How does it work?

NODE is just a simple category on NSObject. When you call node_addChild: on any object, it creates two associated objects; a node_parent is created on the object we are passing in the node_addChild: method, and a node_mutableChildren array is created on the caller.

Is it safe?

That's up to you. This is a category on an NSObject adding associated objects, so it's as dangerous as it gets, but if you use it properly you should be fine. A prefix node_ was added so that name collision risk with other libraries would be minimized, but you still need to keep an eye on that.

Installation

pod 'NODE_'

Contributing

Pull requests, issues and comments are very welcome.

LICENSE

MIT, check LICENSE file.