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# QCPlugInViewController

The `QCPlugInViewController` class communicates (through Cocoa bindings) between a custom patch and the view used for the internal settings of the custom patch. Only custom patches that use internal settings exposed to the user need to use the `QCPlugInViewController` class.

```
class QCPlugInViewController
```

## Overview

You access the internal settings of a custom patch through key-value coding (KVC). All the KVC keys that represent the internal settings of the custom patch must be listed in its `plugInKeys` method.

The view controller for a custom patch expects

- the nib file `File's Owner`  class set to the `QCPlugInViewController` class
- the view outlet connected to the view that contains the editing controls

The controls are bound to the `File's Owner`  as the target and `plugIn.XXX` as the model key path, where `XXX` is the KVC key for a given internal setting of the custom patch instance.

## Topics

### Creating a Controller

[`-  initWithPlugIn:viewNibName:`](/documentation/Quartz/QCPlugInViewController/init(plugIn:viewNibName:))

Creates and initializes a controller for the specified `QCPlugIn` object and nib file.

### Getting the QCPlugIn Object

[`-  plugIn`](/documentation/Quartz/QCPlugInViewController/plugIn())

Returns the `QCPlugIn` object associated with the view controller for the custom patch.

## See Also

  [Quartz Composer Custom Patch Programming Guide](https://developer.apple.com/library/archive/documentation/GraphicsImaging/Conceptual/QuartzComposer_Patch_PlugIn_ProgGuide/Introduction/Introduction.html#//apple_ref/doc/uid/TP40004787)

## Relationships

### Conforms To

[`NSExtensionRequestHandling`](/documentation/Foundation/NSExtensionRequestHandling)

[`NSEditor`](/documentation/AppKit/NSEditor)

[`NSObjectProtocol`](/documentation/ObjectiveC/NSObjectProtocol)

[`Equatable`](/documentation/Swift/Equatable)

[`CustomDebugStringConvertible`](/documentation/Swift/CustomDebugStringConvertible)

[`Hashable`](/documentation/Swift/Hashable)

[`NSSeguePerforming`](/documentation/AppKit/NSSeguePerforming)

[`Sendable`](/documentation/Swift/Sendable)

[`NSStandardKeyBindingResponding`](/documentation/AppKit/NSStandardKeyBindingResponding)

[`NSUserInterfaceItemIdentification`](/documentation/AppKit/NSUserInterfaceItemIdentification)

[`SendableMetatype`](/documentation/Swift/SendableMetatype)

[`NSTouchBarProvider`](/documentation/AppKit/NSTouchBarProvider)

[`NSUserActivityRestoring`](/documentation/AppKit/NSUserActivityRestoring)

[`CustomStringConvertible`](/documentation/Swift/CustomStringConvertible)

[`CVarArg`](/documentation/Swift/CVarArg)

[`NSCoding`](/documentation/Foundation/NSCoding)

### Inherits From

[`NSViewController`](/documentation/AppKit/NSViewController)

---

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