When to use dequeueReusableCellWithIdentifier vs dequeueReusableCellWithIdentifier : forIndexPath

Question

The most important difference is that the forIndexPath: version asserts (crashes) if you didn't register a class or nib for the identifier. The older (non-forIndexPath:) version returns nil in that case.

You register a class for an identifier by sending registerClass:forCellReuseIdentifier: to the table view. You register a nib for an identifier by sending registerNib:forCellReuseIdentifier: to the table view.

If you create your table view and your cell prototypes in a storyboard, the storyboard loader takes care of registering the cell prototypes that you defined in the storyboard.

Session 200 - What's New in Cocoa Touch from WWDC 2012 discusses the (then-new) forIndexPath: version starting around 8m30s. It says that “you will always get an initialized cell” (without mentioning that it will crash if you didn't register a class or nib).

The video also says that “it will be the right size for that index path”. Presumably this means that it will set the cell's size before returning it, by looking at the table view's own width and calling your delegate's tableView:heightForRowAtIndexPath: method (if defined). This is why it needs the index path.

dequeueReusableCellWithIdentifier:forIndexPath: will always return a cell. It either re uses existing cells or creates a new one and returns if there are no cells.

While, the traditional dequeueReusableCellWithIdentifier: will return a cell if it exists i.e if there is a cell which can be reused it returns that else it returns nil. So you would have to write a condition to check for nil value as well.

To answer your question use dequeueReusableCellWithIdentifier: when you want to support iOS 5 and lower versions since dequeueReusableCellWithIdentifier:forIndexPath is only available on iOS 6+

Reference : https://developer.apple.com/library/ios/documentation/uikit/reference/UITableView_Class/Reference/Reference.html#//apple_ref/occ/instm/UITableView/dequeueReusableCellWithIdentifier:forIndexPath:

I have never understood why Apple created the newer method, dequeueReusableCellWithIdentifier:forIndexPath:. Their documentation on them is not complete, and is somewhat misleading. The only difference I've been able to discern between the two methods, is that that older method can return nil, if it doesn't find a cell with the identifier passed in, while the newer method crashes, if it can't return a cell. Both methods are guaranteed to return a cell, if you have set the identifier correctly, and make the cell in a storyboard. Both methods are also guaranteed to return a cell if you register a class or xib, and make your cell in code or a xib file.

For short:

dequeueReusableCell(withIdentifier, for) only works with prototype cells. If you tried to use it when the prototype cell is absence, it would crash the app.

Hollemans M. 2016, Chapter 2 Checklist, IOS Apprentice (5th Edition). pp: 156.