You have a Mac with Xcode and an iPad with Swift Playgrounds. You have a project that you want to develop using both devices. How do you create a project that you can edit in both Xcode and Swift Playgrounds?
Create a Swift Playgrounds App project in Xcode. This project template is designed to work in both Xcode and Swift Playgrounds.
The Swift Playgrounds App project is in the iOS section of the New Project Assistant in Xcode.
When you run into problems with your Swift code, your first instinct may be to add print statements. There’s nothing wrong with print statements, but you can also use Xcode breakpoint actions to print to Xcode’s debug console. Using Xcode breakpoint actions instead of print statements has the following advantages:
Take the following steps to create a breakpoint action equivalent of a print statement.
Click on the left side of Xcode’s editor next to the line of code where you want to set the breakpoint.
The breakpoint appears as a blue arrow in the editor.
Right-click on a breakpoint in Xcode’s editor or in Xcode’s breakpoint navigator (Press Cmd–8) and choose Edit Breakpoint. A popover opens to edit the breakpoint.
Click the Add Action button to add a breakpoint action.
Clicking the Add Action button expands the breakpoint editor.
Choose Log Message from the Action menu. The Log Message action is the equivalent of a Swift print statement.
If you want to show that you entered a function in your code, enter the text in the text field.
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Reached viewDidLoad. |
If you want to print the value of a variable, wrap it with the @ character. The following message:
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Player X: @player.position.x@ |
Prints the following in Xcode’s debug console if the x position is 12:
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Player X: 12 |
At the bottom of the breakpoint editor is a checkbox to automatically continue after running the breakpoint action. Select the checkbox.
Now if you run your project, the messages will appear in Xcode’s Debug console. You created the equivalent of a print statement without writing any code.
To turn off printing, disable the breakpoint. Click on the breakpoint in Xcode’s source editor to disable the breakpoint. Click a disabled breakpoint to enable it.
If you are starting to develop a Swift app that works with a REST API, you may be overwhelmed thinking about all the code you have to write. What if you forget a data structure? What if you forget to add a property to a data structure? Wouldn’t it be nice to have someone create the Swift code for you?
The command-line app CreateAPI makes this possible. Supply a JSON or YAML file that contains the REST API, and CreateAPI creates a Swift package with Swift code for the REST API. By using CreateAPI you can make faster progress on a Swift app that uses REST APIs.
The CreateAPI GitHub page has installation instructions. You can install it using Homebrew or Mint or by cloning the GitHub repository and installing it from source. Installing from source worked for me.
Generating a Swift package with CreateAPI has the following steps:
The most common way to run CreateAPI is to run the create-api generate command with the --output and --config-option options. The following example demonstrates running CreateAPI:
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create-api generate "APIFile.json" --output "./PackageName" --config-option "module=PackageName" |
The name of the JSON file must be in quotes. Replace APIFile.json with the name of the file containing the REST API. Replace PackageName with the name you want for your Swift package.
The CreateAPI GitHub page has a tutorial that contains more detailed instructions.
NOTE
CreateAPI is in its early stages of development. It may not work with every REST API. I was unable to generate a Swift package for GitHub’s REST API.
After creating the Swift package you can add it to your project like any other Swift package. If you have never added a Swift package to a project in Xcode, take the following steps:
Import the package module in your source code files, and you can start using the package in your app.
If you want to see an example of a Swift package that CreateAPI creates, I have a package for Jira’s REST API on GitHub.
Starting in Xcode 14, when you create a multiplatform app project, Xcode creates a single app target with destinations for each platform you want to support: iPhone, iPad, Apple TV and Mac. This article provides an introduction to multiplatform app targets.
Use the Multiplatform App Target if you want people to buy one version of your app on the App Store and run the app on all the platforms you support: iPhone, iPad, AppleTV, and/or Mac. Use separate targets if you plan to charge for each platform separately.
If you plan to sell a Mac version of your app outside the App Store, create a separate app target. Use the multiplatform app target to sell on the App Store and the Mac app target to sell outside the App Store.
Select the target from the target list on the left side of the project editor and click the General button at the top of the project editor to see a list of the app’s platform destinations:
The supported destinations list has buttons to add and remove destinations. If you created a project in an older version of Xcode, you must add destinations to have a single app target that supports iPhone, iPad, AppleTV, and Mac. Older versions of Xcode have separate targets for each platform.
When adding the Mac destination to an app target, you have the following choices:
Choosing Mac uses SwiftUI and/or AppKit for the Mac app. Mac is the best choice for a new app, especially one that uses SwiftUI.
Choosing Mac Catalyst uses UIKit for the Mac app. Mac Catalyst is the best choice if you want to make a Mac version of an existing iOS app.
Choosing Designed for iPad runs the iPad version of the app on Macs with Apple Silicon chips. Choose Designed for iPad if you want a Mac version of your iOS app and don’t want to do any work converting the app.
Xcode can build and run for only platform at a time. How do you specify the platform to build and run?
There’s a jump bar in the project window toolbar.
Click the right part of the jump bar to choose the platform: Mac, a connected iOS device, or an iOS simulator.
Previous versions of Xcode have separate targets for each platform. If you have separate targets with code that should be compiled for a specific platform, make the file a member of that target. But you can’t do that with the multiplatform app target because there’s only one target. What do you do if you have platform-specific source code files?
Tell Xcode what platforms a source code file should compile for. Click the Build Phases button at the top of the project editor and examine the Compile Sources build phase.
Xcode initially sets each source code file to build for each destination. Click on the Filter column for a source code file to open a popover.
Deselect the Allow any platform checkbox and deselect the destinations you don’t want to use. Now that file compiles only for the platforms you specified.
The Get framework is a lightweight Swift framework for working with web APIs. Get is a nice framework, but the README file doesn’t provide much explanation on how to use the framework. This article shows how to start using the Get framework in your apps.
Using the Get framework involves the following basic steps:
Get provides an APIClient class for API clients. Create an instance, supplying the base URL to the network API you want to use. The following example creates an API client for the Jira REST API:
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let client = APIClient(baseURL: URL(string: "https://api.atlassian.com")) |
Get has a Request struct that represents a network request. Fill the Request struct to create a network request. The Request struct has the following fields:
headers field is a Swift dictionary where each key and value are strings.query field is an array of Swift tuples, consisting of two strings.The Get framework defaults to using GET methods and leaving the other fields blank so the only fields you have to fill are the ones you need to make the network call.
To create a request for a GET method, start by creating a variable of type Request. Place the data type you want to return in angle brackets and supply the URL for the network call.
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var request = Request<T>(url: urlPath) |
Replace T with the type you want to return from the network call. Replace urlPath with the URL string for the API call to make.
After creating the request, fill the fields your network call requires.
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request.headers = [ "Accept": "application/json", "Content-Type": "application/json" ] // Sort results alphabetically request.query = [("orderBy", "name")] |
If you have a method that sends data to the server, such as a POST or PUT method, you must create the body data and supply it when creating the request. The body property is a let constant so you can’t set the body after creating the request.
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var request = Request<T>(url: urlPath, body: bodyData) request.method = "POST" request.headers = [ "Accept": "application/json", "Content-Type": "application/json" ] |
The body must conform to the Encodable protocol.
The API client has a send method to send the network request. Supply the request.
Usually a network call returns data. By attaching the value property when sending the request, you will get decoded data back in the type you specified when creating the request.
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return try await client.send(request).value |
You’re going to use this code a lot when using Get. In one line of code you can send a network request and get data back in a form that your app can use.
You update your iOS device to the latest version of iOS. Now you try to run your Xcode project on that device. An alert pops up in Xcode with the message Failed to prepare device for development.
You are getting the Failed to prepare device for development message because the device is running a newer version of iOS than Xcode supports.
Each version of Xcode ships with a version of the iOS SDK. The Xcode Releases site has a list of each version of Xcode along with the iOS SDK. The version of the SDK is the latest version of iOS that version of Xcode supports. You won’t be able to run your Xcode project on a device running a newer version of iOS.
For example Xcode 13.2.1 ships with the iOS 15.2 SDK. If you are running Xcode 13.2.1, you won’t be able to run your project on a device running anything newer than iOS 15.2. If you have a device running iOS 15.4, you won’t be able to run the project on that device with Xcode 13.2.1.
The easiest solution is to install the latest version of Xcode. The latest version of Xcode has the latest version of the iOS SDK so you’ll be able to run and debug your project on a device running the latest version of iOS.
If your Mac is running an older version of macOS, you might not be able to update to the latest version of Xcode. Xcode 13.3 requires macOS 12. If your Mac is running macOS 11 and can’t run macOS 12, you won’t be able to update to Xcode 13.3. What do you do then?
There are two workarounds. The first is to download iOS support files for the newer iOS version and copy them to your Xcode app bundle.
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The second workaround is to deselect the Debug executable checkbox in the Run step of the scheme. After the app launches, attach it to the debugger. The following article provides details and screenshots:
Debugging on iOS 15 with Xcode 12
Starting with iOS 17 Apple no longer includes iOS support files so the first workaround won’t work. According to the following Stack Overflow question:
How to run on iOS 17 Device using Xcode 14
The solution is to run the following command in the Terminal and restart Xcode:
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defaults write com.apple.dt.Xcode DVTEnableCoreDevice enabled |
Keeping up with the latest version of iOS requires using the latest version of Xcode. Xcode takes a long time to install. If you don’t want to be constantly updating Xcode, turn off automatic updates on your iOS device.
It’s frustrating to click the Run button in Xcode and find that your project won’t build and run. Xcode initially shows you a message like Command CompileSwiftSources failed with a nonzero exit code, which really doesn’t help much. How do you find where the error is so you can fix it and run your project?
The first step to figuring out why your project won’t build is to find the compiler errors in your project. Open Xcode’s issue navigator by pressing Cmd–5.
The issue navigator shows the compiler errors in your project. Select an error to show the line where the error is.
To see more detailed information about a compiler error, open the report navigator by pressing Cmd–9. Select a build from the report navigator to see the build steps and errors for that specific build.
Click the Log button (the small button with the horizontal lines) to see a detailed log of that particular build step.
You found the compiler errors in your project. How do you fix them?
I can’t tell you specifically how to fix the errors because I can’t see your code. But I have some general tips to help you fix the compiler errors in your Xcode projects.
When calling functions, make sure the data types for the function arguments match. When the argument types don’t match, you get a compiler error message like the following:
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Can’t convert value of type X to expected argument type Y |
Where X and Y data types.
If a function takes an integer as the first argument and you pass a string, you’re going to get the Can't convert value compiler error.
If I make a typographical error in this article, you’ll still be able to read the article. But if you make one small typo in your code, the project won’t build.
Make sure you spell function names correctly when calling them. If you have a function called doSomething and you call it like the following:
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doSomethng() |
You are going to get a compiler error because you made a typo when calling the function. There is no doSomethng function.
Make sure that you spell variable names correctly when accessing them. If you have a player variable in your app and misspell it,
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move(playr) |
You are going to get a compiler error because there is no playr variable.
Make sure each left brace, bracket, parenthesis, and quotation mark has a matching right one. An extra left or right brace can lead to compiler errors with bizarre messages.
Make sure you import the modules for the frameworks your app uses. If you’re writing an app that works with PDF documents, you must import the PDFKit framework to call its functions in your app.
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import PDFKit |
Does Xcode’s editor frustrate you? Do you have problems with Xcode’s code completion? Do you wish you could use a different text editor to edit the Swift files in your Xcode projects?
Xcode supports opening and editing Swift files in other text editors, such as BBEdit, Sublime Text, TextMate, and Visual Studio Code. Keep reading to learn how to use your favorite text editor to edit the Swift files in your Xcode projects.
Start by making your preferred text editor the default editor for Swift files on your Mac. Perform the following steps to change the default editor for Swift files:
Now when you open a Swift file in the Finder, the file opens in your text editor.
The final step is to open the Swift files in your text editor from Xcode. Select a Swift file in Xcode’s project navigator, right-click, and choose Open with External Editor. The file will open in your text editor.
The changes you make to the text in your text editor will also appear in Xcode. If your project is under version control, an M will appear next to the file in the project navigator, indicating you modified the file.
People learning iOS development without prior programming experience have a lot of questions on installing Xcode, Apple’s tool for developing iOS and Mac apps. This post collects these questions and answers them.
The easiest way to install Xcode is from the Mac App Store. The Mac App Store has the latest version, which usually requires the latest version of macOS.
If your Mac can’t run the latest version of Xcode, go to Apple’s Xcode Downloads page and install an older version. You can also use the Downloads page to install the latest version if you run into problems with the Mac App Store.
A faster way to find Xcode download links is to go to Xcode Releases, a site that has download links for every version of Xcode. Xcode Releases also lists the minimum version of macOS required for each Xcode version.
Another alternative to the App Store is to use the Xcodes app to install Xcode. I have not used Xcodes, but many people swear by it, saying it installs Xcode much faster than the App Store.
Xcode is a huge app. Verifying and expanding it takes a really long time. Even with a fast Internet connection, it will take 1–2 hours to install Xcode.
A Twitter thread explains why expanding takes so much time and provides a tip to speed up the expanding.
If you are installing Xcode from the Mac App Store, you can see the progress of the install from the LaunchPad app.
Xcode requires a lot of disk space to install. You need 4–5 times the size of the Xcode download to install it. The file you are downloading is a compressed file. You need enough free space to temporarily store both the compressed and expanded files. If you have a Mac with a 128 GB drive, you will have a tough time installing Xcode.
If you get an error message saying there isn’t enough free space to install Xcode, free up more disk space until the error message goes away.
Some ways to free up disk space and work around space limitations include the following:
Xcode must be installed on your Mac’s startup disk. If you make an external drive the startup disk, you can install Xcode on an external drive. Use the System Preferences app (Choose Apple > System Preferences from the menu bar) to set the startup disk.
Xcode currently runs only on Macs. Apple has a Swift Playgrounds app for iPad to learn Swift programming. Version 4, which requires iOS 15, lets you develop iOS apps on an iPad.
Not without violating Apple’s license on macOS. Xcode currently runs only on macOS. Apple’s license forbids installing macOS on non-Apple hardware.
Yes you can.
If you are installing Xcode from the Mac App Store, make sure you don’t overwrite your existing Xcode install. When installing from the Mac App Store, Apple adds a file named Xcode in your Applications folder. Change the name of the existing Xcode app on your Mac before installing the new version.
Prior to Xcode 12 Xcode had the following iOS application project templates:
If you create an iOS application project in Xcode 12, you will notice these project templates are missing. In Xcode 12 Apple consolidated these project templates into one template: App. If you are following a tutorial that tells you to choose one of the older templates that no longer exist, choose the App template.