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# protocol_addProtocol(_:_:)

Adds a registered protocol to another protocol that is under construction.

```
func protocol_addProtocol(_ proto: Protocol, _ addition: Protocol)
```

## Parameters

`proto`

The protocol you want to add the registered protocol to.

`addition`

The registered protocol you want to add to `proto`.

## Discussion

The protocol you want to add to (`proto`) must be under construction—allocated but not yet registered with the Objective-C runtime. The protocol you want to add (`addition`) must be registered already.

---

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