All of these reuse identifiers need to be string constants. There are several approaches to this - you can define them as 

`static NSString* const kRZWhateverMyCellIdentifierIsCalled = @"whatevermyidentifieriscalled";`

 at the top of this file, or declare them as

 `OBJC_EXTERN NSString* const kRZWhateverMyCellIdentifierIsCalled;` in the cell subclass headers, then define them at the top of the the subclass implementation:

`NSString* const kRZWhateverMyCellIdentifierIsCalled = @"whatevermyidentifieriscalled"`

The style and/or best practice guide has more info on string constants.