Xcode 8.2 Code Completion Not Working - xcode

For some reason, in Xcode 8.2 my code completion has stopped working. I have cleaned my product, restarted Xcode, restarted my computer, and deleted the derived data, and still no luck. I have submitted this to Apple Support. Has anyone run into this before and been able to fix it?

Update:
As per #Dareon solution below also works for Xcode Version 8.3 (8E162) and 8.3.2 (8E2002). Thanks, #Dareon for the confirmation. :)
I was facing the same issue and following worked for me.
I am using Xcode Version 8.2.1 (8C1002).
Go to Xcode > Preferences > Text Editing
Under Code completion - Uncheck 'Suggest completions while typing'
Quit out of Xcode and then relaunch Xcode.
Go to Xcode > Preferences > Text Editing again
Quit out of Xcode and then relaunch Xcode.
Now go to Code completion and check 'Suggest completions while typing'.
Try typing library function or enum and enjoy!
At least, it worked for me.

Code completion also stopped working for me in Xcode 8.2.1, and no amount of clean-up, derived data throwaway or restart fixed it. After a while, I realized code completion was only broken within the extension scope I was working on. If typed manually, the code would be correctly highlighted and would compile fine, so it was not an issue of the source throwing off whatever parser is in charge of code completion.
Here is the specific context in which it happens, in this very simple example:
struct SomeStruct {
static let foobar1 = {
return NSBezierPath()
}()
}
extension SomeStruct {
static let foobar2 = {
return NSBezierPath()
}()
}
Code completion works fine within the implementation block of foobar1, but not for foobar2. It's the presence of a static let within an extension that seems to trigger it. The issue appears for both struct and class.
Looks like a bug with Xcode, so the only workaround for me was to move foobar2 into the main definition of SomeStruct.

Just restarting Xcode worked for me.

Just clean and build your app once on Generic iOS Device, it might be due to some compile time issue, which disables the intelligence, I am seeing this bug since Xcode 8.2.1.

What worked for me was deleting derived data:
Xcode Preferences -> Locations -> arrow symbol takes you to "Derived Data" -> delete folder

I have had major issues with this as well. For me the code completion and formatting gets lost on my current working source file when ever I do a compile. If I go back and switch to a different tab and come back, after a second or two it starts working again. Sometimes even that doesn't work and I have to stay in the same tab and open up a different file and then navigate back.
Even those methods fail if I leave Xcode open and put the computer to sleep for a few hours and come back. When that happens I have to quit Xcode, sometimes Force Quit it, and then after getting back in do the steps above. But I have had to mess around with it after every single compile or compile and run I do. Haven't tried 8.3 beta yet.

I had the same issue where the "indexing" did not work. As I was using a pod and static libraries. What I did just rebuild the static libraries separately.
Hope this helps.

If you have any large static literals, try commenting them out. Those can sometimes trip up the compiler.

Nothing else worked for me, but this bizarre approach did:
Quit Xcode
Go into your home directory, which if you're like me, is riddled with empty directories with garbage names
rmdir * (as long as you leave the tags off, this will kill only empty directories, which is what you want)
Launch Xcode, happy times again

Related

Xcode 9 Autocomplete Not Working 100% - Partially Working

This morning, Xcode 9.0 (9A235) shows a new/strange Auto Complete box that is not at all what it used to be. How do I get the full auto-complete box so that autocomplete looks like how it usually does?
Try:
Go to Xcode > Preferences > Text Editing
Under Code completion - Uncheck 'Suggest completions while typing'
Quit out of Xcode and then relaunch Xcode.
Go to Xcode > Preferences > Text Editing again
Quit out of Xcode and then relaunch Xcode.
Now go to Code completion and check 'Suggest completions while typing'.
Try typing library function or enum and enjoy!
Deleting the DERIVED DATA folder seemed to fix my issue. Thanks to this post: swift println() not showing autocomplete options while writting code
Things to try:
#1
Run this command in the project directory if you use cocoapods:
rm -rf ~/Library/Caches/CocoaPods;
rm -rf Pods; rm -rf ~/Library/Developer/Xcode/DerivedData/*;
pod deintegrate; pod setup; pod install;
#2
**Clean Cached Data**
Clean the Project -> Cmd+Shift+K
Clean the Build Folder -> Cmd+Shift+Option+K
If you skipped step one:
Delete Derived Data
Xcode Preferences -> Locations ->
Arrow Symbol Takes you to DerrivedData -> Delete Folder
#3
**Check your Build Phase's Compile Sources.**
Every .swift and .m file in the project should be in this list or it won't autocomplete in those files.
#4
**Optimize your Editor:**
Use fileprivate* on every class property and function that you can to reduce the scope of the Compilers work per item.
Write modular/OOP code so you have less code for the compiler to read.
Avoid using Type Inferance when the result is a complex calculation, and try to break down complex calculations into let this = smallerOperation statements
* In Swift 4 private became stricter than fileprivate
In Xcode 12 there have been significant improvements in how often deleting derived data is necessary (though freezing has increased).
Xcode Version 11.0 (11A420a)
I have tried the solution from Lal Krishna for Xcode V11.0. It worked a few times but later I got no result.
I found one solution. You must delete two files:
Library/Developer/Xcode/Derived Data (as described before)
Library/Developer/Xcode/UserData/IDEEditorInteractivityHistory
That solution helps me now. May be useful for others 😉
This can happen when the file is not a member of the Target. Open the file where autocomplete is not working and show the the "Utilities" tab in the top right of Xcode (blue in the screenshot below).
Ensure your Target (typically your app's name) is checked. Autocomplete should work almost instantly without restarting Xcode, cleaning, or deleting Derived Data.
If it is already checked, make sure to uncheck and recheck it again. For me, it did the trick.
I'm using Xcode 10.2 and I had the same issue.
This answer from axel helped me to fix.
Anyway, I'm going to describe a bit more:
Go to YourProject.xcodeproj by clicking with Right Mouse Click and open Show Package Contents
Go to xcuserdata and delete your youruser.xcuserdatad
If you have also the xcworkspace(if you already have any pods installed) then do step 3&4, if not then just skip step 3&4:
Go to YourProject.xcworkspace by clicking with Right Mouse Click and open Show Package Contents
Go to xcuserdata and delete your youruser.xcuserdatad
Quit Xcode
Delete Derived Data by using Terminal:
rm -rf ~/Library/Developer/Xcode/DerivedData
Open Xcode and check if it works.
This can also happen if you redundantly named your files. For example,
Data.swift
Data.swift
Here's a bit of workaround but works.
Clean the project... Command + Shift + K
Clean the build folder... Command + Shift + Options(Alt) + K
Delete derived data for the project...
This can be done with the help of this link:
How can I delete derived data in Xcode 9?
Close XCode.
Reopen XCode (let the indexing complete) and Build the project... Command + B
Once it will be done with building, The suggestions will be back. I have tried it twice.
Update:
Sometimes the issue can be as simple as Duplicate file names.
Carefully check if any new file names added by you are conflicting with older files.
In Xcode 11.4, even if you move an existing file to another group, the suggestions disappear. This can be cured simply by restarting Xcode.
Removing the file from the Test Targets fixed my problem.
After a long time of searching, I finally fixed the issue for me. In Xcode > Preferences > Text Editing, in "Code Completion", I had "Use Escape key to show completion suggestions" checked for some reason. As soon as I unchecked this box, auto completion worked like a charm, without even needing to restart Xcode! (Xcode 10)
Please try doing this:
Select the file >> check if the file is added to UITesting or UnitTesting targets (File inspector -> Target Membership). If so, please uncheck those two and make sure only the project target is selected. Then build and try if autocomplete is working fine.
This worked for me. Hope it help someone.
For Xcode 11.4 (11E146)
Back Slash in folder name breaking the autocompletion feature, If this is the case remove it and build again.
I added here what was going on in my project just in case it can help someone else... I had 2 files with the same name and I didn't realise.
Just lost a day trying to solve the autocomplete nightmare of Xcode (9.2). Deleting derived data seemed to work briefly then things reverted. Reboots etc and other suggested voodoo failed to make a difference.
I gave up and download the 30 day trial of AppCode from Jet Brains. Autocomplete worked fine there and this maybe coincidence but it then started working again in my project in Xcode. Can't guarantee that it'll keep working...
It seems to be file specific in my case (Xcode 9.2) For me the fix was:
Delete problem file (remove reference)
Clean and Build
Add file back into the project (I did not check test targets)
Build again
Finally after 3 hours of trying everything - autocomplete works as it should.
Problems mostly because there are missing location of some files in project navigator (build errors)
Press command+1 to open Project Navigator pane
Check if there are any missing files
Or you can:
Delete DerivedData (command+shift+K)
Clean build folder (command+shift+option+K)
Press build again (command+B)
You should see build error that Xcode could not find some files that prevent build tool to process auto complete.
Correct and fix any missing files that you see.
Hope this helps
Use Command + B
or Command + R to Build or Run the project
Xcode sometimes messes up ;)
Xcode 11.3, macOS catalina
process parsecd achieve 100% of cpu, so kill it helps me
goto underneath directory and delete all folders on it.
{Your User}/Library/Developer/Xcode/DeriveData
It worked for me.
For me it was happening in my test file, because it wasn't part of a target for some reason. Setting it's target membership solved the issue.
For me, the problem occured when I discarded all the changes of one file (under Source Control > Commit), which effectively deleted the file. This is what I wanted and I thought that the file and all references to it would be delted too.
However, there was still a reference to the file (shown in red) in the Project navigator. Deleting the (now non-existant) file in the Project navigator magically brought auto-completion back.
No amount of cleaning, deleting derived data, etc helped. I only realized the deleted file was still showing when I tried to build my project, which of course failed because it couldnt find that file.
Hope this will help someone save 30 minutes :)
check whether you selected the Suggest completions while typing in Xcode -> Preferences -> Text Editing
navigate to user->Library->Developer->Xcode->DerivedData in Finder and delete the DerivedData folder
My case might appear too specific to help, but it might give someone an idea of how to solve broken auto-completion. Xcode 10.2.1.
In my case, auto-complete stopped working entirely and non of these other answers helped me. In addition, the fan on the computer could be heard to go louder indicating something was overworking (no other apps running), it should be noted I was editing on a MacBook Pro laptop. It seemed to be linked with the editor struggling to parse the equation I'd written:
switch mtype {
case .indeterminate:
newPosition.x = (frame.width - mainFigureText.frame.width) / 2
case .right:
newPosition.x = (((frame.width / 2) - mainFigureText.frame.width) / 2) + (frame.width / 2)
case .left:
newPosition.x = (((frame.width / 2) - mainFigureText.frame.width) / 2)
}
I was looking to animate a text view left, right, or to the middle depending on user prefs. The newPosition is a CGPoint that the text will animate to. Anyway, I split the equations up and all of a sudden auto-complete started working and the fan went quiet! I've been able to recreate this specific problem more than once by re-typing the above code and then replacing it with:
let halfFrameWidth: CGFloat = frame.width / 2
let middleLeft = (halfFrameWidth - mainFigureText.frame.width) / 2
switch doseType {
case .right:
newPosition.x = middleLeft + halfFrameWidth
case .left:
newPosition.x = middleLeft
default:
newPosition.x = (frame.width - mainFigureText.frame.width) / 2
}
I would like to add one more to the pile of solutions, because it is the only one that worked for me and is nowhere to be found here.
Xcode normally comes with two default build configuration for every project. Release & Debug. I have an extra one for my unit tests called Testing. In Xcode 10.1, 10.2, 10.3 and 11 beta, the new build system does not seem to like it and will only auto-complete if you either use Release or Debug. Any custom build configuration breaks auto-completion in mixed (swift + objc) project with unit tests.
I faced the same problem in Xcode 11.3.1. In my case The issue was cause due to duplicate file names / Deleted file name. Better to run the application once and check whether there are any deleted files/classes so that you will get a syntax error.
This Link helped me. Open the Build Settings & fill the framework search paths. See the below image.
Build errors can break the autocompletion feature in Xcode.
I had the issue with 100% not working auto-complete, none of written here helped. One thing I noticed – it was broken right after adding some entities into .xcdatamodel file, which have codegen class definition by default.
So I wasn't surprised when using old-style codegen none (and generating classes of course) fixed the issue immediately, even without restarting the xcode.
With Xcode 11.1, simply performing Clean Build Folder or deleting derived data was not enough to fix autocomplete.
Only after restarting my Mac, everything was back to normal
If you have issue with weird completion/auto-completion/intellisense (not showing default stuff like delegates and datasource protocols methods) just change your target (e.g. from simulator iPhone 8 to real device), build the project and switch back to your original target.
Similar with issues with Interface Builder (storyboards) not showing anything, but only "nothing selected" whenever you select any part of the view. Just switch to other Xib/Storyboard (or even create new), check if it works there and switch back.
These workarounds worked for me in both cases (had both issues in one day with one project on Xcode 10.2.1). From what I've seen all over internet forums it seems these are bugs never fixed since Xcode 6.x or so.
Cheers!

Xcode Command-Slash Shortcut to Comment Only Works Sometimes

I'm having issues with Xcode being quite unreliable when using the keyboard shortcut to comment or uncomment code ⌘+/. I can't seem to find a real pattern as to when it breaks, but it usually happens after building and running my code on the simulator. It will not work again until I edit something in any one of my code files. Even if I switch to another file in the main view, commenting via shortcut does not work. Other keyboard shortcuts, such as indenting ⌘+[ continue to work just fine.
Do other people have this issue, and if so, have you found a solution? I know it seems like a small complaint, but when running and then quickly trying to comment out a block of code to check the effect, it's a bit of an inconvenience.
I am using Xcode 6.1 (6A1052d) on OXS Yosemite 10.10 (14A389) and developing in Objective-C for iOS if that matters.
For an Xcode 8, solution is
sudo /usr/libexec/xpccachectl
and restart your computer.
Hit ⌘+] once and then ⌘+/ will start working again.
You can hit ⌘+[ to undo the indentation effect.
Update:
Please note- This solution was provided prior to Xcode 8 launch so it may not work for everyone. If you are still facing problem, kindly refer to #CryingHippo's answer instead of downvoting.
I have done this numerous times with Xcode 8. Latest being Xcode 10.1 where I would just quit Xcode and go to Applications and rename Xcode to something else, e.g. Xcode 2, launch it, quit again and rename back. It starts working after that. No Mac restart or Terminal commands required.
It still works as of Xcode 10.1. I cannot believe Apple still hasn't fixed it properly.
None of the above solutions worked for me with Xcode 8.0 (final). If you also have Xcode 8.1 beta installed like I do, try this: simply rename /Applications/Xcode-beta.app to something else, then restart Xcode 8. Oddly enough, that did the trick.
Oscahie's answer actually works for non-beta versions of Xcode as well. Here are the steps to follow, based on Sam's comment:
Close Xcode
In the Application folder, rename Xcode.app (or similar) to Xcode2.app. You might need to type in your password.
Open Xcode, then close it.
Rename Xcode2.app back to what it was before.
(Optional) Spend 5 minutes wondering why this worked.
No need to reboot!
I didn't have to do any of the above. A simple reboot fixed it.
A simple workaround works good for me with following steps:
Comment any line i.e. simply add "//" in front of a line.
Press Command + "/" and it starts working.
It might help someone.
In my code I had this sequence:
/*" BLABLA MY COMMENTS */
All the code under this was not "commentable".
Removed the " and it was ok !
Hope it helps!
I just had the same issue after setting up a new Mac with Xcode 10.1 using the German keyboard layout.
The solution was to disable the Keyboard shortcut in system settings for the help menu.
System settings > Keyboard > Shortcuts > App shortcuts.
There was a shortcut for all apps to show the help menu.
If you have that, click the checkbox to disable it
I am using Xcode 8.1 (not beta) and I had the same problem, not able to cmd+\ to comment. Restart Xcode not working for me but RESTART my Mac SOLVED the problem without a need to remove cache.
I had this problem in Xcode 8.0. Even though I already move Xcode 8.1-beta somewhere else (It's at Application/Xcode otherversions/Xcode 8.1-beta.app). I have to delete it to the trash, restart Xcode 8.0, and cmd+/ somehow works again.
Just quit xcode completely and restart. Worked for xcode 8.2
I was also facing this issue, when having multiple Xcode installed.
In which Xcode version you are you facing this problem, to solve this, the Xcode should be in the Application Folder. If it resides in the subfolder than move it to the Application folder directly.
I found a pattern where toggle comments do not work.
In fact, uncomment works, but comment don't, from keyboard as well as from the Editor menu.
This happens in a specific file, suggesting there is something in text that prevents from working.
I tested on XCode 10.1ß and on XCode10.2, on different machines.
Text before this line can be commented, text after cannot (I kept text exactly as is)
let alert = UIAlertController(title: "" /*"Teste texte"*/, message: "Love\nWe'll recommend more for you" /* Entrez des chiffres"*/, preferredStyle: .alert)
It appears that the /* … */ inside the UIAlertController() is the cause.
If I suppress both comments inside, everything works OK.
I filed a bug report. # 49907361
Nothing above worked, even after trying multiple times.
Just reinstalled new xcode using AppStore app, previously I installed xcode after downloading from
developer.apple.com/downloads. that is .xip file
Wait for new update and install.
Another reason may be that xcode isn't in Application directory.

XCode 6 autocomplete stopped working

XCode 6 Beta 5 and autocomplete stopped working. I thought problem in Beta 5 but I've reinstall to Beta 4 and it's still not work but it did before. I check preferences for "suggests" and I tried to delete Derived Data but it doesn't help
Clear derived data.
Under build settings, select Always Search User Paths to "YES".
Clean the project.
This happened to me recently because I had a /* */ style comment after the #end of my #implementation.
Not sure why that would break autocomplete but moving the comment into the implementation fixed autocomplete.
There seems to be a lot of reasons autocomplete breaks. Just adding to the list..
I found the solution. Problem was in an array.
I have big array like:
let array:[NSString] = ["first","second"...]
I changed it to
var array = ["first","second"...]
I don't why it's happened but it works. It was so hard to find the problem.
I was having this problem.
This is what worked for me.
Clear derived data.
Window -> Organizer -> "Select you project" -> Delete Derived Data.
Clean the project
Quit Xcode ----- this is very important. You might have to restart you computer.
Open Xcode again
Hope this works for you. This worked on 2/9/2015
Check if the .m file has been checked in "Target Membership"
Tried to clean/delete derived data multiple times. Autocomplete was disabled in some files, but not App Delegate. After a while I saw red libraries int he project navigator. Those are managed by cocoapods. The solution turned out to be:
Navigate to the project root folder
Delete "Pods" directory
open terminal, type cd
drag the project folder there to get full path
run pod install
Upon reinstalling pods, syntax highlighting and code completion is restored in the affected files.
For me it was because it was a new problem since upgrading my version of Xcode. After downloading the documentation again, everything worked fine.

XCode 4 osx 10.9 - folding methods crashes

After updating to osx 10.9, in any of my projects doing the following crashes Xcode 4.6.3:
fold a method, if statement, for loop, etc
click on a different file
click back on the file with the folded code
When clicking back on the file I notice that all the line numbers are gone but the one at the very top (which is usually some random number and it sort of flashes a bit). Less than 5 seconds after clicking on this file XCode crashes.
This is repeatable. When I reopen Xcode and open the project, the problem persists. Now I am unable to access that file. I've tried closing Xcode and releasing the memory in RAM. I've tried removing the reference in the project and adding it back. Yes the problem persists.
This is massively frustrating and has completely derailed my development. Has anyone else had this issue? Anyone know how to solve it?
Here's the crash report if it's helpful.
-GW
Ok I figured it out, but am still curious as to why this is happening and how I can still fold my code without this problem.
click on the problem file.
click anywhere where the code should be (sometimes all the code appears to be gone)
goto Editor > Code Folding > Unfold All
That cleared it up.
It happened to me too. I fully share frustration and reasons why not going to rev 5.
Here's my solution :
exit xcode
go to your myProject.xcodeproj file
look inside the package for myProject.xcworkspace file (right click / Show Content)
back up myProject.xcworkspace outside your xcode hierarchy
delete myProject.xcworkspace file
restart xcode (a clean myProject.xcworkspace will be created).
NOTE: Works for me, but I'm not using workspaces. I have not tried, but I suppose that if you want to preserve your workspace settings you'd have to selectively delete the UserInterfaceState.xcuserstate files further down in the package hierarchy?
I had to delete UserInterfaceState.xcuserstate file to solve these reoccurring code/comments folding crashes in Xcode 4.6.3 running on OSX 10.9.
This file can be found at projName.xcodeproj(Show Package Contents)->project.xcworkspace(Show Package Contents)->xcuserdata->username.xcuserdatad->UserInterfaceState.xcuserstate
Note that you will loose all the saved user state info of your project, which means all your open tabs will disappear, folded code will be unfolded etc. And the crashes may start reoccuring if you fold any code or comment again.

Xcode 4 code sense is not working

I am running a "old" Xcode 3 project in Xcode 4 and code sense is not working for my own classes. I have tried following:
Clean/rebuild
Remove Derived Data
Installing 4.3 documentation
Restart
Without any luck.
Sometimes the code sense works but mostly I just get "No Completions".
Try this:
Open Organizer then Project Tab.
Clear the "Derived Data". Xcode should re-index your project then and code sense should work. At least worked for me.
I know this is late, but for reference: http://sealedabstract.com/code/when-xcode-4s-code-completion-autocomplete-breaks/
Close the project, leaving XCode still running.
Open XCode’s Organizer window, go to the Projects Tab, select the correct project, and hit the Delete button next to “Derived Data”.
Quit XCode.
Navigate to your project’s .xcodeproject file in Finder. Right-click, choose “Show Package Contents.”
Leave the project.pbxproj file, but delete the project.xcworkspace file, any .pbxuser files, and the entire userdata folder.
Open the project in XCode. You will see XCode riding high on the CPU usage for around 10-60 seconds, depending on the size of your project. The activity window will say “Indexing”
When your CPU spike returns to earth, code completion will be working again.
There's a lot of deleting going on there so please be careful, but this definitely worked for me.
I've been doing this, and it's worked multiple times for me (after trying all of the above previously).
Edit: Now I just hit space, backspace (the mac version) and rebuild... works nice. Then, remember to scroll (sometimes the colors don't show up until you scroll somewhere)
Find your prefix file: "ProjectName_prefix.pch".
Comment out some line. (basically change it)
Build your project, doesn't matter if it fails or not.
Uncomment it.
Build again.
I'm betting only step 2 (modify the prefix) is what does it, but these essentially get you back to running. Suddenly everything magically recolors itself and completes functions.
Good luck if that doesn't fix it, perhaps try doing this to your dependency pch files (three20 or FB api's)
Clearing the "Derived Data" only works temporarily for me. I have to do it and then restart Xcode like 3-4 times each day to get code sense working again.
I found out the real cause is in the Target's Build Settings. I moved everything from Header Search Paths to User Header Search Paths and it is fixed. In my case, the framework I'm working with is RestKit.
BTW, I came up with this because I was adding another project (QuickDialog) into my project and I was curious that it is using User Header Search Paths, but not Header Search Paths. Here is the difference between them.
You can able to fix that issue by change build settings like this, PreCompile Prefix Headers :NO
FYI, if one file doesn't have code sense but the rest of your project does, check that its added to a target. Once I did that I got code sense back in that file.
It's been ages but the answer is just to move the code into a new folder and the code sense should be working now.
This happened when I added a new Objective-C Class and the code sense doesn't work only on the newly added .m and .h files (on XCode 4 latest update during this post).
Close all xcode windows
Delete all your projects from xcode>window>organizer and restart your project. It will now sense and index your project properly.
I wrote about it in detail here.
Basically my fix was that with localization. I upgraded from xcode 3.2.5 to xcode 4 and then screwed around with built in interface builder and turned on localization for a XIB file accidently which placed my source files in en.lproj directory. After moving them back to Classes folder it worked perfectly.
Again, for the sake of helping others with this issue which, in my case, happened upon upgrading to Xcode 4.3.
Of course I tried the solutions offered in this post, and none of them worked. But the suggestion to move the location of the project in Finder brought back some Code Sense, but the suggestions didn't make any sense.
I ended up deleting my project and re-cloned it from the git repository.That brougt back Code Sense for me...
I open a second project in the background whenever my Xcode's code sensing stops working (it usually works the first time i open the project but after a while code sense no longer works). So what i do is to open a second project in Xcode. Xcode will start indexing the second project and magically the code sense for my main project is back.
Running Xcode 4.3.1 on Lion
Hope this helps someone.
From this comment here I was able to debug the problem on my end, it seemed to be a bad -w flag that the clang preprocessor wasn't recognizing properly. Basically, running
defaults write com.apple.dt.Xcode IDEIndexingClangInvocationLogLevel 3
in Terminal increases the verbosity of the indexer, and should help you track down issues. Open Console.app and look for messages from Xcode, the search string IDEIndexingClangInvocation helped me find them.
For me it happened simply because the file had no target membership. If the first few answers did not work for you, go to your .m file (presumably it's this file that you're having trouble with), open the Utilities view (Edit -> Utilities -> Show File Inspector) and under "Target Membership" check the target to which you want this file to belong.

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