The method -viewDidUnload is deprecated in iOS 6.0. Here offers a way to remove all -viewDidUnload snippets from your project's view controllers in batch.

remove_all_viewdidunload_snippets_from_your_projects_vcs.md

Remove All -viewDidUnload Snippets From Your Project's VCs

As Apple's Official Doc said:

-viewDidUnload is deprecated in iOS 6.0. Views are no longer purged under low-memory conditions and so this method is never called.

Meanwhile, it's better to remove all -viewDidUnload implements from projects that the deployment target is iOS 6.0 or later. But removing it one by one is boring, especially you've hundreds of controllers & several projects.

So, is there any script or command can do this batch job?

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Solution

Good news, I figured out a command for Vim, I'm sure it'll make your life easier. ;)

Open Vim in desired root dir (generally, it'll be your root dir of your all controller files), press Shift : to enter command-line mode, run the command below:

:args **/*.m | argdo %s/^-\ (void)viewDidUnload\_.\{-}}\n^$\n//ge | update

This will replace all

- (void)viewDidUnload
{
  [super viewDidUnload];
  ...
}

to empty, in other words, the -viewDidUnload snippet will be removed. But note, there's a blank line after the implement. If you don't want to include it, use

:args **/*.m | argdo %s/^-\ (void)viewDidUnload\_.\{-}}//ge | update

instead.

Note: This will include lib files as well when you're in your project's root dir. I suggest go to your Controllers' root dir, then all files & you will be happy with the result. ;)

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Tip:

After that, you'd better check whether all -viewDidUnload were removed, run the command below on terminal of your desired root dir:

$ find . -type f -iname "*.m" -exec grep -i "viewDidUnload" {} +

It should result with no output. Otherwise, some targets missed, you can locate it easily cause it'll list all files that not managed correctly, then just remove it manually (This might happen if your - (void)viewDidLoad is -(void)viewDidLoad without a space, or something else).

Finally, you can run

$ git diff -b --color-words

to see the result. Enjoy it! ;)

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Further reading about the command

• args **/*.m: Sets arglist to contain all .m files in current directory and it's subdirectories;
• argdo: Run the following command(s) on all arguments in arglist;
• %s/^-\ (void)viewDidUnload\_.\{-}}\n^$\n//ge: Vim RegEx to replace -viewDidUnload implement snippet to empty;
  • \_.: Find any character including end-of-line (linebreak).
  • \{-}: Match as few as possible (stopping at the first }, e.g. \{-}h will stop at the first h);
  • }: The last item to match;
  • \n: Line-break;
  • ^$\n: blank line.
• update: Save modification only if the buffer has been modified.

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Reference

• Search Across Multiple Lines
• Search and Replace in Multiple Buffers

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Related Thread on SO: Way to remove all -viewDidUnload from project's view controllers.