Sunday, March 17, 2013


Core Data is possibly one of the most useful frameworks in iOS. People have different feelings towards it, but i'm a solid fan. One issue that i'm sure everyone has had with core data at one point or another is getting data in and out of Core Data. This ultimately led to creation of the FRCoreDataOperation project.

A few months ago I started using FRCoreDataOperation to serialize Core Data objects to disk. Sure you could do this with plists, but thats a little too restrictive especially if you want the serialized data to be compatible with other applications and platforms. Usually my format of choice is CSV, as you can import it into excel/ google docs easily, also python has a great module for loading CSV data.

For another project I found myself needing to do the same thing again, the classic sign that it was time to do make something reusable and adaptable. So FRCoreDataExportOperation was born. FRCoreDataExportOperation is a concrete subclass of FRCoreDataOperation and can be used without subclassing. Below is an example of how you use the class.

There are a series of initializers that you can use in tandem with the class, but the one you'll probably most interested in is below.

As you can see by using a predicate and sort descriptors along with the entity name you can select the objects you want to export. The export operation also supports relationships, it's not completely recursive, and will only explore entities that have a direct relationship with the entity you specified.

The next step is to select a formatter, the actual serialization format is completely abstracted from the class and is performed by the object assigned to FRCoreDataExportOperation's entityFormatter property. Thus far i've only created the FRCoreDataEntityFormatter, FRCSVEntityFormatter, but you can create your own by implementing the FRCoreDataEntityFormatter protocol.

The FRCSVEntityFormatter is somewhat customizable, and allows you to specify a NSArray with the  keypaths that you want to be serialized to disk. The columns will be written in the order they appear in the array. If you choose to use the formatter without a whitelist, all of the properties will be written in the alphabetical order of the property name.

Best of all you can get this for yourself via Cocoapods, pod is aptly called FRCoreDataOperation

Happy exporting

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