https://github.com/fespinoza/howtoplayground
A collection of useful "how-tos" for working in Xcode Playgrounds
https://github.com/fespinoza/howtoplayground
how-to tips xcode-playground
Last synced: 5 months ago
JSON representation
A collection of useful "how-tos" for working in Xcode Playgrounds
- Host: GitHub
- URL: https://github.com/fespinoza/howtoplayground
- Owner: fespinoza
- Created: 2018-02-17T18:14:57.000Z (over 8 years ago)
- Default Branch: master
- Last Pushed: 2019-07-29T18:14:37.000Z (almost 7 years ago)
- Last Synced: 2025-04-06T00:43:39.439Z (about 1 year ago)
- Topics: how-to, tips, xcode-playground
- Size: 5.86 KB
- Stars: 4
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# How to...in playgrounds
## 9. Decode a JSON string
In order to create a simple test for your decodable code:
```swift
import Foundation
// in this case the show name is {"A"-Team}, hence the \\ to espace the {"}
let jsonString = """
{
"id": "345team",
"name": "\\"A\\"-Team",
}
"""
struct Show: Decodable {
let id: String
let name: String
}
guard let rawData = jsonString.data(using: .utf8),
let card = try? JSONDecoder().decode(Show.self, from: rawData) else {
fatalError("couldn't parse the Raw JSON string, the json content must be malformed")
}
print(Show.name)
```
## 8. Decode a JSON file
Useful to provide test data to ViewControllers, when you don't have an internet connection.
Given that you have a `sample-data.json` file in your `Resources` folder
```swift
import Foundation
guard
let jsonFileURL = Bundle.main.url(forResource: "sample-data", withExtension: "json"),
let jsonData = try? Data(contentsOf: jsonFileURL),
let decodedResult = try? JSONDecoder().decode(MyModel.self, from: jsonData) else {
fatalError("coudln't read the file from the main bundle")
}
```
## 7. Use images in markdown
First, you need to add an image to the `Resource` folder of a playground named `design.png`, then from the code, you can simply add:
```swift
/*:
## Inserting a markdown image
*/
```
and it will render correctly
## 6. Programatically create an instance of NSViewController
Another one for mac, in playgrounds
```swift
import Cocoa
import PlaygroundSupport
class MyViewController: NSViewController {
override func loadView() {
self.view = NSView(
frame: CGRect(x: 0, y: 0, width: 300, height: 200)
)
self.view.wantsLayer = true
self.view.layer?.backgroundColor = NSColor.blue.cgColor
}
}
let viewController = MyViewController()
PlaygroundPage.current.liveView = viewController
```
The important part, is that the method `loadView` must be implemented, as using the empty initializer,
the code will throw an error missing the view if `loadView` hasn't been implemented
## 5. Open a image for iOS
Given an image added to the _Resources_ folder, like `tutorial-01.jpg`, I would open it from a playground like:
```swift
let image = UIImage(named: "tutorial-01.jpg")
```
## 4. Open a image for macOS
Given an image added to the _Resources_ folder, like `tutorial-01.jpg`, I would open it from a playground like:
```swift
let fileURL = Bundle.main.url(forResource: "tutorial-01", withExtension: "jpg")!
let image = NSImage(contentsOf: fileURL)
```
## 3. Write unit tests
Tip taken from john sundell's [Writing unit tests in Swift playgrounds][john-testing-playground] post
```swift
import Foundation
import XCTest
class MyTestClass: XCTestCase {
func testSomething() {
// write test here
}
}
class TestObserver: NSObject, XCTestObservation {
func testCase(_ testCase: XCTestCase,
didFailWithDescription description: String,
inFile filePath: String?,
atLine lineNumber: Int) {
assertionFailure(description, line: UInt(lineNumber))
}
}
let testObserver = TestObserver()
XCTestObservationCenter.shared.addTestObserver(testObserver)
MyTestClass.defaultTestSuite.run()
```
## 2. Test an instance of UIView
When attempting to preview an instance of `UIView`, it's important to call `view.layoutIfNeeded()` otherwise the view would never layout on Playgrounds.
```swift
let view = MyCustomView()
view.frame = CGRect(x: 0, y: 0, width: 300, height: 150)
view.layoutIfNeeded()
```
## 1. Use a custom font
First, add the `my-custom-font.otf` file to the `Resources` folder of the playground, then within the playground, you can use the font as follows:
```swift
let fontName = "my-custom-font"
let fontURL = Bundle.main.url(forResource: fontName, withExtension: "otf")
CTFontManagerRegisterFontsForURL(fontURL! as CFURL, .process, nil)
let uiFontName = "MyCustomFont-Bold"
let customFont = UIFont(name: uiFontName, size: 16.0)
```
[john-testing-playground]: https://www.swiftbysundell.com/posts/writing-unit-tests-in-a-swift-playground