Xcode9.2编译报错：找不到-lopencv_core.3.3.1库，已装OpenCV3.4.0求助

Let’s work through this linker error — your hunch about version mismatch is totally correct. Here’s how to resolve it step by step:

1. Check for hardcoded version references in your project #

First, double-check your Other Linker Flags in Xcode. If you’ve explicitly added -lopencv_core.3.3.1, that’s the root issue. Replace it with either:

• -lopencv_core (uses the default symlinked version in your OpenCV install)
• -lopencv_core.3.4.0 (matches your installed 3.4.0 version)

You can confirm the exact library filename by running this in Terminal:

ls /usr/local/Cellar/opencv/3.4.0_1/lib | grep opencv_core

You should see something like libopencv_core.3.4.0.dylib — use that version suffix if you go with the explicit flag.

2. Clean Xcode’s cached data #

Xcode often holds onto old dependency paths or cached builds, which can cause issues even after you update settings. To fix this:

• Open Xcode, go to Xcode > Preferences > Locations
• Under Derived Data, click the arrow icon to open the folder
• Delete the folder corresponding to your project
• Quit and restart Xcode, then do a full clean (Cmd+Shift+K) before rebuilding

3. Verify your Library Search Paths and linked frameworks #

Even though you’ve set the path, make sure:

• Your Library Search Paths points directly to /usr/local/Cellar/opencv/3.4.0_1/lib (not just /usr/local/lib — symlinks can sometimes cause confusion)
• In Linked Frameworks and Libraries, you’ve added the actual .dylib files from the 3.4.0_1 folder, not any leftover 3.3.1 files that might still be on your system

4. Hunt for leftover old OpenCV files #

If uninstalling/reinstalling didn’t clear everything, check for residual 3.3.1 files:
Run this in Terminal to find all OpenCV core libraries:

find /usr -name "libopencv_core*.dylib" 2>/dev/null

If you see any files with 3.3.1 in the name, delete them (you’ll need sudo for system-level files):

sudo rm /path/to/libopencv_core.3.3.1.dylib

5. Check for third-party dependencies #

If your project uses any external libraries or pods that depend on OpenCV 3.3.1, those could be forcing the linker to look for the old version. Double-check your Podfile or any imported frameworks to ensure they’re compatible with 3.4.0.

Give these steps a try — the most likely fix is updating the hardcoded linker flag and clearing Xcode’s cache. Let me know if you hit any snags!

内容的提问来源于stack exchange，提问作者Braandyy_