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rakuyoMo/JSONPreview 1.3.3
🎨 A view that previews JSON in highlighted form, it also provides the ability to format and collapse nodes.
⭐️ 16
πŸ•“ 1 week ago
.package(url: "https://github.com/rakuyoMo/JSONPreview.git", from: "1.3.3")



JSONPreview inherits from UIView. You can use it to format your JSON data and highlight it.

Also, JSONPreview provides fold and expand features that allow you to collapse nodes that you are not interested in at the moment and re-display them at any moment.

All of the features in JSONPreview are written using native methods, which means you get a great experience on Apple platforms.


Below is a gif of about 25 seconds (about 2.5M) that shows the effect of previewing JSON using this library.



  • iOS 10 or later.
  • Xcode 10.0 or later required.
  • Swift 5.0 or later required.



pod 'JSONPreview'

Swift Package Manager

Or add the following to your Package.swift file:

dependencies: [
  .package(url: "https://github.com/rakuyoMo/JSONPreview.git", from: "1.3.2")


In version 1.3.0, we removed the diagonal swipe feature. Now if a JSON row is not displayed open, it will be displayed folded instead of going beyond the screen. If you wish to use this feature, please use version 1.2.3

  • β˜‘ Supports formatting to display JSON data.

  • β˜‘ Supports highlighting JSON data, with multiple color and font configuration options.

  • β˜‘ Provides fold and expand features for Array and Object.

  • β˜‘ Based on UITextView, which means you can copy any content from JSONPreview.

  • JSONPreview provides limited, incomplete format checking functionality, so it is not provided as a primary feature. For details, see: Format check


After downloading the project, ViewController.swift file contains part of the test code, just run the project Check the corresponding effect.

  1. Create the JSONPreview object and add it to the interface.
let previewView = JSONPreview()

  1. Call the preview(_:style:) method to preview the data in the default style:
let json = "{\"key\":\"value\"}"

  1. If you want to customize the highlight style, you can set it through the HighlightStyle and HighlightColor types:

Among them, ConvertibleToColor is a protocol for providing colors. Through this protocol, you can directly use the UIColor object, or easily convert such objects as 0xffffff, #FF7F20 and [0.72, 0.18, 0.13] to UIColor objects.

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

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

previewView.preview(json, style: style)

Format Check


For rendering, JSONPreview performs only limited format checks, including:

The following references to "previous node" do not include space, \t, or \n.

  • The JSON to be previewed must begin with { or [.
  • The last node of : must be .string.
  • The previous node of , can only be one of .null, .link, .string, .number, .boolean, }, and ].
  • { must exist in the previous node, and the previous node cannot be {.
  • } must exist in pairs with {.
  • [ must exist on the previous node, while the previous node cannot be ].
  • ] must exist in pairs with [.
  • The " must appear in pairs.
  • The previous node of " can only be one of {, [, ,, and :.
  • Spell-checking for null, true, and false.

Syntax errors other than these do not trigger rendering errors.


In 1.2.0, .link rendering has been added. While rendering, JSONPreview performs limited de-escaping operations.

The following de-escaping operations are supported in different versions.

Unless otherwise specified, the following functions are cumulative.

  • 1.2.0: Supports replacing "\\/" with "/".

Data Flow Diagram



  • ☐ Support Carthage.
  • ☐ Support for intel macOS.


Thanks to Awhisper for his valuable input during the development of JSONPreview.


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


Stars: 16
Last commit: 17 hours ago
jonrohan Something's broken? Yell at me @ptrpavlik. Praise and feedback (and money) is also welcome.

Release Notes

1.3.2 - Available for iOS 15
7 weeks ago


  • Uses a new method for calculating the height of the row number view Cell.


  • Adapted for iOS 15.

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