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# makeDefaultLibrary()

Creates a Metal library instance that contains the functions from your app’s default Metal library.

```
func makeDefaultLibrary() -> (any MTLLibrary)?
```

## Return Value

A new [`MTLLibrary`](/documentation/Metal/MTLLibrary) instance if the method completes successfully;
otherwise `nil`.

## Discussion

Xcode compiles all the Metal source files (ending in `.metal`) in an Xcode project into a single default library.

---

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