CPTableView -enumerateAvailableViewsUsingBlock: and -_enumerateViewsInColumns:rows:usingBlock:

These methods allow to enumerate visible data views or data views in specified columns and rows.
-enumerateAvailableViewsUsingBlock: is the counterpart of cocoa's -enumerateAvailableRowViewsUsingBlock: except that it enumerates data views instead of CPTableRowView and the block has an additional column parameter.

Applied the second method where it is relevant, making the code more compact and readable.