JSONPreview is a JSON preview component that allows you to format your JSON data and display it with syntax highlighting. Additionally, JSONPreview offers fold and expand functionality, allowing you to collapse nodes you're not currently focusing on and re-display them at any time.

JSONPreview inherits from UIView and implements related features based on UITextView. The entire framework is entirely implemented based on native frameworks, which means when using this framework on Apple platforms, you can achieve a better user experience.

Below is a roughly 25-second gif (approximately 2.5M) demonstrating the effect of previewing JSON using this library.

pod 'JSONPreview'

• Select File > Swift Packages > Add Package Dependency
• Add https://github.com/RakuyoKit/JSONPreview.git
• Select "Up to Next Major" with "2.3.1"

Or add the following content to your Package.swift file:

dependencies: [
  .package(url: "https://github.com/RakuyoKit/JSONPreview.git", from: "2.3.1")
]

• Support for formatting JSON data.
• Support for syntax highlighting of JSON data, offering various color and font configuration options.
• fold and expand functionality for Array and Object (except tvOS).
• Allow setting the initial state of nodes, .folded or .expand.
• Implemented based on UITextView. This means you can copy any content from JSONPreview.
• Search the contents of JSON using text.
• Switch between displaying JSON with or without wrapping lines at any time.

Additional Details:

1. JSONPreview provides limited and incomplete formatting checks, so this feature is not offered as a primary function. Details can be found in: Format check.
2. Version 1.2.0 added support for rendering links. Alongside rendering, JSONPreview performs limited unescaping: supporting replacing "\\/" with "/".

After downloading the project, the Demo directory contains sample projects. You can run the project to see the corresponding effects.

1. Create a JSONPreview object and add it to the interface:

let previewView = JSONPreview()
view.addSubview(previewView)

2. Call the JSONPreview.preview method to preview the data with the default style:

let json = "{\"key\":\"value\"}"
previewView.preview(json)

If you want to customize the syntax highlighting style, you can set it using HighlightStyle and HighlightColor:

ConvertibleToColor is a protocol for providing colors. Through this protocol, you can directly use UIColor objects or easily convert values like 0xffffff, #FF7F20 and [0.72, 0.18, 0.13] into UIColor objects.

let highlightColor = HighlightColor(
    keyWord: ConvertibleToColor,
    key: ConvertibleToColor,
    link: ConvertibleToColor,
    string: ConvertibleToColor,
    number: ConvertibleToColor,
    boolean: ConvertibleToColor,
    null: ConvertibleToColor,
    unknownText: ConvertibleToColor,
    unknownBackground: ConvertibleToColor,
    searchHitBackground: ConvertibleToColor?,
    jsonBackground: ConvertibleToColor,
    lineBackground: ConvertibleToColor,
    lineText: ConvertibleToColor
)

let style = HighlightStyle(
    expandIcon: UIImage?,
    foldIcon: UIImage?,
    color: highlightColor,
    lineFont: UIFont?,
    jsonFont: UIFont?,
    lineHeight: CGFloat,
    boldedSearchResult: Bool
)

previewView.preview(json, style: style)

You can also configure the initialState parameter to set the initial state of JSON child nodes.

// By default, all nodes are initially in a collapsed state during preview.
previewView.preview(json, style: style, initialState: .folded)

When rendering JSON, JSONPreview performs limited formatting checks.

Known conditions that trigger "error rendering" include:

• Values of unconventional JSON types. Supported types are object, array, number, bool, string, and null.
• Checking for formatting in number, such as scientific notation and decimals.
• Spelling check for true, false, and null.
• For scientific notation, the next node after {E/e} must be +, -, or a digit.
• Missing , separators between elements in an array.
• Missing , separators between elements in an object.
• No : after a key in an object.
• object has : after a key but lacks a value.
• Keys in object are not strings.

Apart from the explicitly mentioned conditions, other errors might trigger "error rendering". Additionally, there could be some errors outside the scope of formatting checks that might result in missing content in the JSON.

It's recommended not to overly rely on the formatting check feature of JSONPreview and to use it for previewing correctly formatted JSON as much as possible.

Thanks to Awhisper for valuable insights during the development of JSONPreview.

JSONPreview is available under the MIT license. For more information, see LICENSE.