> For the complete documentation index, see [llms.txt](https://docs.apryse.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.apryse.com/ios/viewer/night-mode.md).

# Page color mode

Enhance your PDF viewing experience with PDFViewCtrl's special color modes: night mode, inverted color mode, and custom color mode. Learn how to set and customize color modes for optimal reading. The

[`PDFViewCtrl`](https://sdk.apryse.com/api/ios/Classes/PTPDFViewCtrl.html) has three special color modes: night mode, inverted color mode, and custom color mode. In night mode, colors are adjusted to improve reading at night, in inverted color mode, all colors are inverted, and in custom color mode, you can set a custom color for text and the background color.

![](https://4149080208-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FgY6xtY9ZQd9XMpvWlGM0%2Fuploads%2Fgit-blob-343375628c2dff8eebaa3c1a94bea5d0a9ff71ae%2F66f05a343d0341455b509a9282075128a28bd48a-1430x544.png?alt=media)

Color modes from left to right: normal color mode, inverted color mode, night mode and custom color mode.

## Set the color mode

To set the color mode:

1. Find the constant value of the color mode

| Color mode          | Constant value                                                                                                                                               |
| ------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| Normal color mode   | [`e_ptpostprocess_none`](https://sdk.apryse.com/api/ios/Enums/PTColorPostProcessMode.html#/c:@E@PTColorPostProcessMode@e_ptpostprocess_none)                 |
| Night mode          | [`e_ptpostprocess_night_mode`](https://sdk.apryse.com/api/ios/Enums/PTColorPostProcessMode.html#/c:@E@PTColorPostProcessMode@e_ptpostprocess_night_mode)     |
| Inverted color mode | [`e_ptpostprocess_invert`](https://sdk.apryse.com/api/ios/Enums/PTColorPostProcessMode.html#/c:@E@PTColorPostProcessMode@e_ptpostprocess_invert)             |
| Custom color mode   | [`e_ptpostprocess_gradient_map`](https://sdk.apryse.com/api/ios/Enums/PTColorPostProcessMode.html#/c:@E@PTColorPostProcessMode@e_ptpostprocess_gradient_map) |

1. Call [`setColorPostProcessMode(_ mode: PTColorPostProcessMode)`](https://sdk.apryse.com/api/ios/Classes/PTPDFViewCtrl.html#/c:objc\(cs\)PTPDFViewCtrl\(im\)SetColorPostProcessMode:).
2. Optionally, set the `PDFViewCtrl` background color for the best visual result. You can set background color by calling [`setBackgroundColor(_ r: UInt8, g: UInt8, b: UInt8, a: UInt8)`](https://sdk.apryse.com/api/ios/Classes/PTPDFViewCtrl.html#/c:objc\(cs\)PTPDFViewCtrl\(im\)SetBackgroundColor:g:b:a:).For example, set the background color to black for night mode:

![](https://4149080208-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FgY6xtY9ZQd9XMpvWlGM0%2Fuploads%2Fgit-blob-e2fd299ceaf0f87ad2aecf8f82269abbfed10f62%2F11a67ce052a7a6199ddd8c12ea5f1144a758c901-392x292.png?alt=media)

{% tabs %}
{% tab title="Swift" %}
{% code lineNumbers="true" %}

```swift
pdfViewCtrl.setBackgroundColor(0, g: 0, b: 0, a: 255)
```

{% endcode %}
{% endtab %}

{% tab title="Obj-C" %}
{% code lineNumbers="true" %}

```objc
[self.pdfViewCtrl SetBackgroundColor:0 g:0 b:0 a:255];
```

{% endcode %}
{% endtab %}
{% endtabs %}

1. If you are using `postprocess_gradient_map`, call [`setColorPostProcessColors(_ white_color: UIColor!, black_color: UIColor!)`](https://sdk.apryse.com/api/ios/Classes/PTPDFViewCtrl.html#/c:objc\(cs\)PTPDFViewCtrl\(im\)SetColorPostProcessColors:black_color:) to set the white and black points. For example, for a sepia effect, try:

{% tabs %}
{% tab title="Swift" %}
{% code lineNumbers="true" %}

```swift
let darkBrown = UIColor(red:0.24, green:0.15, blue:0.04, alpha:1.0)
let lightBrown = UIColor(red:0.96, green:0.88, blue:0.79, alpha:1.0)
pdfViewCtrl.setColorPostProcessColors(lightBrown, black_color: darkBrown)
```

{% endcode %}
{% endtab %}

{% tab title="Obj-C" %}
{% code lineNumbers="true" %}

```objc
UIColor* darkBrown = [UIColor colorWithRed:0.24 green:0.15 blue:0.04 alpha:1.0];
UIColor* lightBrown = [UIColor colorWithRed:0.96 green:0.88 blue:0.79 alpha:1.0];
[self.pdfViewCtrl SetColorPostProcessColors:lightBrown black_color:darkBrown];
```

{% endcode %}
{% endtab %}
{% endtabs %}

1. Update `PDFViewCtrl` to redraw the contents:Sample result when using `postprocess_gradient_map` and a light/dark brown for the white/black color:

{% tabs %}
{% tab title="Swift" %}
{% code lineNumbers="true" %}

```swift
pdfViewCtrl.update(true)
```

{% endcode %}
{% endtab %}

{% tab title="Obj-C" %}
{% code lineNumbers="true" %}

```objc
[self.pdfViewCtrl Update:YES];
```

{% endcode %}
{% endtab %}
{% endtabs %}

![](https://4149080208-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FgY6xtY9ZQd9XMpvWlGM0%2Fuploads%2Fgit-blob-147581910216d35f3a25250590fcd193fc50dc02%2F763253aeabe683dda72a42172754b12942b3ec44-948x1228.png?alt=media)


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