XCode 9.3 beta 2中某Objective-C项目自动补全失效求助

Hey there, sorry to hear you're hitting this autocomplete snag—super frustrating when that happens, especially since other projects are working fine! Let's walk through some targeted fixes that usually resolve this kind of project-specific issue:

• Clean your project and delete Derived Data
  First, start with the basics: go to Product > Clean Build Folder (use the shortcut Cmd+Shift+K for a full clean). Then manually delete the Derived Data for your problematic project:

  1. Open Finder and press Cmd+Shift+G
  2. Paste ~/Library/Developer/Xcode/DerivedData into the dialog
  3. Locate the folder tied to your project (it’ll have a random string appended to the project name) and delete it.

• Force Xcode to reindex your project
  Corrupted indexing is a top culprit for broken autocomplete. Here’s how to reset it:

  1. Close your project in Xcode
  2. Go to Window > Projects
  3. Find your project in the list, click the Delete button next to "Derived Data"
  4. Quit Xcode entirely, then reopen your project and let it reindex (you’ll see a progress bar in the top-right corner).

• Check key Build Settings
  Misconfigured settings can block autocomplete without obvious warning signs:

  • Search for Index-While-Building Functionality in your project’s Build Settings—ensure it’s set to YES for all targets.
  • Verify the correct Swift/Objective-C version is selected for your project and targets (mismatched versions often break indexing).
  • Look for unusual compiler flags in Other C Flags or Other Swift Flags that might be interfering with the indexer.

• Hunt for hidden syntax errors
  A single malformed file can crash Xcode’s indexer without showing obvious errors in the Issue Navigator. Try:

  • Commenting out recently modified files one by one and checking if autocomplete starts working again.
  • Scanning your code for subtle issues like unclosed brackets, missing semicolons (for Obj-C), or invalid type annotations that might throw off the indexer.

• Reset Xcode preferences (last resort)
  If all else fails, corrupted preferences might be the issue. Note that this will reset all your Xcode settings (shortcuts, themes, etc.):

  1. Quit Xcode completely
  2. Open Terminal and run:

     defaults delete com.apple.dt.Xcode
     

  3. Restart Xcode and reconfigure your settings as needed.

• Test with a stable Xcode version
  If you have access to Xcode 9.2 (a stable release), try opening the project there. If autocomplete works fine, this is likely a bug in the 9.3 beta. In that case, submit a bug report to Apple via Xcode > Report an Issue to help them fix it in a future beta.

Give these steps a try one by one—usually one of them gets autocomplete back on track for project-specific issues. If none work, sharing a bit more about the project (like whether it’s a Swift/Obj-C mixed project, or any recent major changes you made) could help narrow things down further!

内容的提问来源于stack exchange，提问作者Amit Majumdar