Could not insert new outlet connection error

This problem seems to be an Xcode bug which creeps up mostly when you replace a file with a new file of the same name. Xcode seems to keep a reference of the older file of the same name.

Anyhow, the way to fix this seems to be -

1. Clean the project

2. Click <Your Project> in Project Navigator view. Go to Compile Sources under Build Phases of the target for which you are building. Remove and add back the .m file which is giving you trouble.

3. Alternatively, in the File Inspector (Utilities view) of the NIB file, under Target Membership, uncheck and check back the target name.

4. Restart Xcode for good measure.

5. Of course, deleting and adding back the .m file alone should fix it too.

Steps 1. and 2. alone fixed it for me.Feel free to ask if any step needs expanding.

Cheers and happy coding :)

I fixed this issue by deleting the .m file (reference only) then adding it back in to the project. I think XCode gets corrupted at times (and I'm on the latest 4.6).

https://stackoverflow.com/a/16166878/521946

Try to clean your project and restart Xcode.
If it still cannot be connected, follow the Utilities navigation view of Xcode, in the Target membership section, uncheck & check the checkbox, it will be work. Maybe you should rebuild the project after unchecking.