Storyboard static cells: dequeueReusableCellWithIdentifier returns nil

问题:

Using storyboard, static cells, in cellForRowAtIndexPath: the line

UITableViewCell *cell =     [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; 

always returns nil.

I have checked the following:

• Identifier of the cell is correctly set in IB/Storyboard and I use the same identifier in code. I verified this many times.
• I have not instantiated the view controller elsewhere (which was the problem in this stackoverflow question).

My view controller is a subclass of UITableViewController, of course, wrapped into an ad hoc navigation controller in storyboard. Suspecting that my view controller somehow does not know about the cell identifiers defined in storyboard because it might be another instance, here is the code the "instantiates" it. In prepareForSegue:, I use

CustomViewController *vc = [[[segue destinationViewController]     viewControllers] objectAtIndex:0]; 

Other customizations of the view controller done here (setting properties etc.) works fine.

I am using static cells because the number of sections and rows does not change, and each cell contains static text (and other controls or text fields to be edited).

It seems to me this is a very common task (customize static cells from storyboard in the view controller's datasource methods). What am I doing wrong?

回答1:

With static content in a table view, you do not implement any of the datasource methods (including tableView:cellForRowAtIndexPath:, so you would never dequeue the cells. There is no dequeuing for static content (that you can get involved in, anyway).

If you want to get a pointer to a particular cell:

• get it from the table view using cellForRowAtIndexPath::

  UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath]; 

• have an outlet to the specific cell and customise it directly.

• Iterate through the cells and check the reuseIdentifier property to get the cell you are interested in.

Any of these things can be done in viewWillAppear or similar.

If you want to have completely different content in your cells to that found on the storyboard then static cells probably aren't the right choice. You should use dynamic prototypes (note you can have multiple prototypes in the storyboard) with the traditional data source methods instead.

回答2:

The solution was to use prototype cells rather than static cells. I am still giving the check to @jrturton as he was the first who got me the idea.

Another interesting error I just solved: with prototype cells of type "Custom", if you try to fill cell.textLabel with text, it will just automatically work, but all your other subviews behave very strangely. I just use my custom label now, and everything works fine.

Cheers, thanks everyone for helping out.

回答3:

Different to the answer above,

UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath]; 

will not work. But the mentioned method to create an outlet to the cell itself is working.

It is also possible to place views such as UIButtons or UITextFields on the cell and have outlets for those as well.

Both methods can also be used in combination. E.g. set the cell.textLabel.text for a particular cell and have another control which will be accessed from the controls outlet.

回答4:

In the storyboard, the Static Cells CAN'T implement the Methods in the <UITableViewDataSource> protocol.

So you could use the methods which ones are include in <UITableViewDelegate>.

回答5:

You can still use dataSource/delegate methods of static UITableView, you just don't have to create new cells.

If you want to modify cells with dataSource methods, inside cellForRowAtIndexPath: :

UITableViewCell * cell = [super tableView:tableView cellForRowAtIndexPath:indexPath]; 

and then start modifying cell.

文章来源: Storyboard static cells: dequeueReusableCellWithIdentifier returns nil