How to run Xcode 11.4 on macOS Mojave 10.14.6

Question

Background on problem:

I have an iPhone 6s that has updated itself to iOS 13.4. Before the iOS update, I could code + run my app on the device from Xcode, great.

Now I can't run my app from Xcode on the device to test my code, as it says:

Xcode could not locate device support files This iPhone 6s is running iOS 13.4 (17E255), which may not be supported by this version of Xcode. An updated version of Xcode may be found on the App Store or at developer.apple.com. 

So I tried installing the latest Xcode (11.4) which now says I have to update my whole OS to Catalina.

I don't want to do this as my system is working fine and I have heard bad things about that release.

Question:

Is there a way I can get Xcode building to my iPhone without updating my whole OS and potentially screwing up my whole machine?

Answer 1

You cannot run Xcode 11.4 on Mojave but you can add support for iOS 13.4

• Download the 13.4 image from this repo
• Quit Xcode
• Unzip the archive and move the folder into /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport
• Launch Xcode

Consider that this way adds only the support for iOS 13.4, nothing else.

Update: This does not work with iOS 14 because iOS 14 requires Xcode 12.

Answer 2

Here's an alternative solution that doesn't require downloading files from an untrusted source:

1. Install the latest release of Xcode that runs on Mojave (currently Xcode 11.3.1). It can be downloaded from Apple's developer pages.

2. From the same page, download a release of Xcode that supports iOS 13.4 (for example Xcode 11.4.1). Unzip it, rename it to "Xcode-11.4.1.app" and move it to the Applications folder, but don't run it.

3. Add a symbolic link for iOS 13.4 from the DeviceSupport folder in Xcode 11.4.1 to Xcode 11.3.1, as described in Peter Steinberger's Gist.

If you use the versions used in this answer, the command to add the symbolic link would be

sudo ln -s /Applications/Xcode-11.4.1.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/13.4 /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport