Using storyboard in ios7 the content view is explicitly viewed under the Table View Cell in the story board editor (opposed to previous version
I don't really know the answer, but I can suggest work around this issue:
1) Copy existing cell from other tableview to the one you're working on.
2) You will have contentView under your cell now. Design this cell by adding your views.
3) Create a class for your cell, e.g NewCell, then manually create IBOutlet in this class:
@property (nonatomic, strong) IBOutlet UILabel* mainLabel;
4) Assign the cell class in storyboard to the class you just created. After this step, you can drag the outlet from storyboard to class.
I'm not sure if this is a bug for XCode 5 or it is intended, and I'm looking for better solutions as well.