So the solution is to compile Xdebug manually, manually specifying the actual location of the header files, which are still provided by Xcode, just at a different location. The first step is to get Xcode from the App Store. Once Xcode installed, we have to get the command line tools: xcode-select -install. A Mac running macOS Catalina, with Xcode (and the Xcode Command Line Tools) installed. Note: I see no reason this should not work for macOS Sierra 10.12- Mojave 10.14, but I did all my testing on a clean install of the latest release of macOS Catalina 10.15.3. So if you’re using a version other than that, you’re on your own.

To get the latest features and maintain the security, stability, compatibility, and performance of your Mac, it's important to keep your software up to date. Apple recommends that you always use the latest macOS that is compatible with your Mac.

Learn how to upgrade to macOS Big Sur, the latest version of macOS.

Check compatibility

The version of macOS that came with your Mac is the earliest version it can use. For example, if your Mac came with macOS Big Sur, it will not accept installation of macOS Catalina or earlier.

If a macOS can't be used on your Mac, the App Store or installer will let you know. For example, it might say that it's not compatible with this device or is too old to be opened on this version of macOS. To confirm compatibility before downloading, check the minimum hardware requirements:

• macOS Catalina 10.15 hardware requirements
• macOS Mojave 10.14 hardware requirements
• macOS High Sierra 10.13 hardware requirements
• macOS Sierra 10.12 hardware requirements
• OS X El Capitan 10.11 hardware requirements
• OS X Yosemite 10.10 hardware requirements

Download macOS using Safari on your Mac

Safari uses these links to find the old installers in the App Store. After downloading from the App Store, the installer opens automatically.

• macOS Catalina 10.15 can upgrade Mojave, High Sierra, Sierra, El Capitan, Yosemite, Mavericks
• macOS Mojave 10.14 can upgrade High Sierra, Sierra, El Capitan, Yosemite, Mavericks, Mountain Lion
• macOS High Sierra 10.13 can upgrade Sierra, El Capitan, Yosemite, Mavericks, Mountain Lion

Safari downloads the following older installers as a disk image named InstallOS.dmg or InstallMacOSX.dmg. Open the disk image, then open the .pkg installer inside the disk image. It installs an app named Install [Version Name]. Open that app from your Applications folder to begin installing the operating system.

• macOS Sierra 10.12 can upgrade El Capitan, Yosemite, Mavericks, Mountain Lion, or Lion
• OS X El Capitan 10.11 can upgrade Yosemite, Mavericks, Mountain Lion, Lion, or Snow Leopard
• OS X Yosemite 10.10can upgrade Mavericks, Mountain Lion, Lion, or Snow Leopard

Xcode is the tool developers use to build apps for the Apple ecosystem – MacOS, iOS, and all things Apple.

This guide will walk you through how to successfully install Xcode onto your Mac, from start to finish.

Here are some handy tips to know before you get started:

• Xcode only runs on a mac. If you are on a PC, sadly you won't be able to use Xcode.
• You'll need a good, stable internet connection. The latest version is around 8 gigabytes in size.
• Be sure to have at least 30 gigabytes of free space on your computer. The latest .xip file (v11.4.1 at the time of writing) is ~8 gigabytes zipped. When you unzip it, that's another 17 gigabytes. Then you'll need the command line tool, which is yet another 1.5 gigabytes.

Here's an overview of the steps to install Xcode

1. Download Xcode
2. Install the command line tool
3. Open the new version
4. Delete files

Note that I have listed some Terminal commands in the steps below. These commands can be typed into your present working directory. This means that you don't need to navigate to any particular folder.

If you really want to, you can first type cd before typing the commands in the below steps. This will return you back to the home folder.

Step #1: Download Xcode

There are two ways to do this. For the latest version and a theoretically 'easy' installation, you can use the App Store. I don't recommend this option.

I prefer to use the developer site. This comes with the bonus option of being able to download any version you'd like.

Option #1: Download via the App Store for the latest version (not my preferred option)

In theory, this should be a seamless and pain-free process. But if the installation fails for any reason on the last step, it is very hard to troubleshoot.

There are a few reasons for failure, and no easy way to know which is the underlying cause. If you do encounter a failure, you will need to re-download the entire file again each time you try to fix the failure. As the latest version is 8 gigabytes, I didn't much enjoy this approach.

But if you're feeling brave, here are the steps:

• Open the App Store on your mac
• Sign in
• Search for Xcode
• Click install or update

Option 2: Download via the Developer site for a specific version (my preferred option)

1. Head to the 'more' section of the Apple developer website
2. Sign in with your iTunes account id
3. Type in the version that you'd like, and download the Xcode_x_x_x.xip file. Keep in mind that Xcode 11.4.1 is 8 gigabytes, so this will take awhile depending on your internet connection.
4. Once the file is downloaded, click on .xip to extract it. Your laptop will extract it to the same folder you downloaded it to. This extraction process is automatic. You don't need to do anything more after you click on the .xip file. This step will take a few minutes.
5. [Optional] Once extracted, rename the application to “Xcode11.x.x” if you are using multiple versions.
6. Drag application to the Applications folder
7. [Optional] Set the new Xcode version as the default. Open Terminal and type sudo xcode-select -switch /Applications/Xcodex.x.x.app . Replace x.x.x with the version number. For example: Xcode11.4.1.app. You will need to enter in your computer admin password. I'm pretty sure this will update the default Xcode version for all users on your computer, so best to check with other users first

Step #2: Install the command line tool (CLT)

If you have multiple users on your computer, you will need to update the CLT for each user.

Download .dmg

To update the CLT, go to app developer website and download the command line tool .dmg.

If you have never installed Xcode before, you may be able to update with your Terminal by typing in xcode-select --install instead of visiting the developer website.

But if you have an existing version of Xcode installed on your machine, you'll probably see this error:

This means you'll need to go to the developer website instead.

Catalina Xcode Installer

Installing the CLT

When the .dmg has finished downloaded, double click the file to open it. This will open a little window that looks like this:

Double click the box and follow the prompts to install the CLT. It will take a few minutes to complete.

It may ask you at the end of the installation whether you want to move this to the trash bin. When it does this, it's talking about moving the .dmg file to the trash bin. Since you should no longer need this file. I always say yes to this.

Step #3: Open Xcode

Install Xcode On Catalina

Open the Applications folder and open the new version of Xcode. If you renamed Xcode, make sure you open the correct application

Xcode may prompt you to install additional components. Click install. This will take a few minutes.

While it's installing, check that your default Xcode version is the one you just downloaded:

• Open Terminal
• Type brew config
• You should see “CLT” and “Xcode” versions, as well as everything else. This should reflect the version that you have just downloaded. In my case, I downloaded Xcode 11.4.1.

Once the components are installed, Xcode will launch. You should be able to pick up your old projects and continue where you left off seamlessly*.

Catalina Xcode Cannot Be Installed

*Note that if you use any proxy tools, such as Charles, you will need to re-install those certificates in your simulator again.

If you encounter any errors while trying to build or run a project, check which device you are trying to launch. The new version may not remember the device you were using before. If so, click on the device and choose 'Add additional simulators' from the drop down menu to add the device you want.

Catalina Install Xcode

Step #4. Delete the files

Catalina Xcode Install Fails

If you don't need the older versions of Xcode on your computer, you can uninstall them and get some hard drive space back.

Catalina Install Xcode Command Line Tools

You can also delete the .xip file of the version you just downloaded, as well as the CLT.dmg file.

Catalina Xcode Install Command Line Tools

That's everything. I hope this has helped you successfully install Xcode. Have fun with it!