To develop an app for multiple platforms imposes higher demands on our development machine. One reason for this is that we often want to run one or multiple simulators or emulators on our development machine. Different platforms also have different requirements with regard to what is needed to begin development. Regardless of whether we are using Mac or Windows, Visual Studio will be our IDE. There are several versions of Visual Studio, including the free community edition. Go to https://visualstudio.microsoft.com/ to compare the available versions of Visual Studio. The following list is a summary of what we need to begin development for each platform:

• iOS: To develop an app for iOS, we need a Mac. This could either be the machine that we are developing on or a machine on our network, if we are using one. The reason that we need to connect to a Mac is that we need Xcode for compiling and debugging an app. Xcode also provides the iOS simulator.

• Android: Android apps can be developed on either macOS or Windows. Everything you need, including SDKs and simulators, are installed with Visual Studio.

• UWP: UWP apps can only be developed in Visual Studio on a Windows machine.

There are two main tools that are required to develop applications for iOS and Android with Xamarin on a Mac. These are Visual Studio for Mac (if we are only developing Android applications, this is the only tool we need) and Xcode. In the following sections, we will take a look at how to set up a Mac for app development.

Before we install Visual Studio, we need to download and install Xcode. Xcode is the official development IDE from Apple and contains all the tools they provide for iOS development, including SDKs for iOS, macOS, tvOS, and watchOS.

We can download Xcode from the Apple developer portal (https://developer.apple.com) or from Apple App Store. I recommend that you download it from App Store because this will always provide you with the latest stable version. The only reason to download Xcode from the developer portal is if we want to use a prerelease version of Xcode, to develop for a prerelease of iOS, for example.

After the first installation, and after each update of Xcode, it is important to open it. Xcode often needs to install additional components after an installation or an update. You also need to open Xcode to accept the license agreement with Apple.

To install Visual Studio, we first need to download it from https://visualstudio.microsoft.com.

When we start the Visual Studio installer via the file we downloaded, it will start to check what we already have installed on our machine. When the check has finished, we will be able to select which platforms and tools we would like to install. Note that Xamarin Inspector requires a Visual Studio Enterprise license.

Once we have selected the platforms that we want to install, Visual Studio will download and install everything that we need to get started with app development using Xamarin, as shown in the following screenshot:

Visual Studio will use the Android emulators provided by Google. If we would like the emulator to be fast, then we need to ensure that it is hardware-accelerated. To hardware-accelerate the Android emulator, we need to install the Intel Hardware Accelerated Execution Manager (HAXM), which can be downloaded from https://software.intel.com/en-us/articles/intel-hardware-accelerated-execution-manager-intel-haxm.

The next step is to create an Android Emulator. First, we need to ensure that the Android emulator and the Android OS images are installed. To do this, go through the following steps:

1. Go to the Tools tab to install the Android Emulator:

2. We also need to install one or multiple images to use with the emulator. We can install multiple images if, for example, we want to run our application on different versions of Android. We will select emulators with Google Play (as shown in the following screenshot) so that we can use Google Play services in our app, even when we are running it in an emulator. This is required if, for example, we want to use Google Maps in our app:

3. Then, to create and configure an emulator, go to the Android Device Manager from the Tools tab in Visual Studio. From the Android Device Manager, we can start an emulator if we have already created one, or we can create new emulators, as shown in the following screenshot:

4. If we click the New Device button, we can create a new emulator with the specifications that we need. The easiest way to create a new emulator here is to select a base device that matches our needs. These base devices will be preconfigured, and that is often enough. However, it is also possible to edit the properties of the device so that we can get an emulator that matches our specific needs.

Because we will not run the emulator on a device with an ARM processor, we have to select either an x86 processor or an x64 processor, as shown in the following screenshot. If we try to use an ARM processor, the emulator will be very slow:

We can either use a virtual or a physical Windows machine for development with Xamarin. We can, for example, run a virtual Windows machine on our Mac. The only tool we need for app development on our Windows machine is Visual Studio.

If we already have Visual Studio installed, we must first open Visual Studio Installer; otherwise, we need to go to https://visualstudio.microsoft.com to download the installation files.

Before the installation starts, we need to select which workloads we want to install.

If we want to develop apps for Windows, we need to select the Universal Windows Platform development workload, as shown in the following screenshot:

For Xamarin development, we need to install Mobile development with .NET. If you want to use Hyper-V for hardware acceleration, we can deselect the checkbox for Intel HAXM in the detailed description of the Mobile development with .NET workload on the left-hand side, as shown in the following screenshot. When we deselect Intel HAXM, the Android emulator will also be deselected, but we can install it later:

When we first start Visual Studio, we will be asked whether we want to sign in. It is not necessary for us to sign in unless we want to use Visual Studio Professional or Enterprise, in which case we have to sign in so that our license can be verified.

If we want to run, debug, and compile our iOS app, then we need to connect it to a Mac. We can set up the Mac manually, as described earlier in this chapter, or we can use Automatic Mac Provisioning. This will install Mono and Xamarin.iOS on the Mac that we are connecting to. It will not install the Visual Studio IDE, but this isn't necessary if you just want to use it as a build machine. We do, however, need to install Xcode manually.

To be able to connect to the Mac—either to a manually-installed Mac or using Automatic Mac Provisioning—the Mac needs to be accessible via our network and we need to enable Remote Login on the Mac. To do this, go to Settings | Sharing and select the checkbox for Remote Login. To the left of the window, we can select which users are allowed to connect with Remote Login, as shown in the following screenshot:

To connect to the Mac from Visual Studio, use the Pair to Mac button in the toolbar (as shown in the following screenshot), or, in the top menu, select Tools | iOS and finally Pair to Mac:

A dialog will appear showing all the Macs that can be found on the network. If the Mac doesn't appear in the list of available Macs, we can use the Add Mac button in the bottom left corner to enter an IP address, as shown in the following screenshot:

If everything that you require is installed on the Mac, then Visual Studio will connect and we can start building and debugging our iOS app. If Mono is missing on the Mac, a warning will appear. This warning will also give us the option to install it, as shown in the following screenshot:

If we want a fast Android emulator that works smoothly, we need to enable hardware acceleration. This can be done using either Intel HAXM or Hyper-V. The disadvantage of Intel HAXM is that it can't be used on machines with an Advanced Micro Devices (AMD) processor; you have to have a machine with an Intel processor. We can't use Intel HAXM in parallel with Hyper-V.

For these reasons, Hyper-V is the preferred way to hardware accelerate the Android emulator on a Windows machine. To use Hyper-V with the Android emulator, we need to have the April 2018 update (or later) for Windows and Visual Studio version 15.8 (or later) installed. To enable Hyper-V, you need to go through the following steps:

1. Open the Start menu and type Turn Windows features on or off. Click the option that appears to open it, as shown in the following screenshot:

2. To enable Hyper-V, select the Hyper-V checkbox. Also, expand the Hyper-V option and check the Hyper-V Platform checkbox. We also need to select the Windows Hypervisor Platform checkbox, as shown in the following screenshot:

3. Restart the machine when Windows prompts you to.

Because we didn't install an Android emulator during the installation of Visual Studio, we need to install it now. Go to the Tools menu in Visual Studio, click on Android, and then Android SDK Manager.

Under Tools in Android SDK Manager, we can install the emulator by selecting Android Emulator, as shown in the following screenshot. Also, we should ensure that the latest version of Android SDK Build Tools is installed:

We recommend installing the NDK (Native Development Kit). The NDK makes it possible to import libraries that are written in C or C++. NDK is also required if we want to AOT compile an app.

The Android SDK allows for multiple emulator images to be installed simultaneously. We can install multiple images if, for example, we want to run our application on different versions of Android. Select emulators with Google Play (as shown in the following screenshot) so we can use Google Play services in our app even when we are running it in an emulator.

This is required if we want to use Google Maps in our app, for example:

The next step is to create a virtual device to use the emulator image. To create and configure an emulator, go to the Android Device Manager, which we will open from the Tools tab in Visual Studio. From the Device Manager, we can either start an emulator—if we already have created one—or we can create new emulators, as shown in the following screenshot:

If we click the New Device button, we can create a new emulator with the specifications that we need. The easiest way to create a new emulator here is to select a base device that matches our needs. These base devices will be preconfigured, which is often enough. However, it is possible to edit the properties of the device so that we can get an emulator that matches our specific needs.

We have to select either an x86 processor (as shown in the following screenshot) or an x64 processor since we will not run the emulator on a device with an ARM processor. If we try to use an ARM processor, the emulator will be very slow:

If we want to develop UWP apps, we need to activate developer mode on our development machine. To do this, go to Settings | Update & Security | For developers. Then, click on Developer Mode, as shown in the following screenshot. This makes it possible for us to sideload and debug apps via Visual Studio:

If we select Sideload apps instead of Developer Mode, we will only be able to install apps without going via Microsoft Store. If we have a machine to test, rather than debug our apps on, we can just select Sideload apps.