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# onAppear(perform:)

Adds an action to perform before this view appears.

```
nonisolated func onAppear(perform action: (() -> Void)? = nil) -> some View
```

## Parameters

`action`

The action to perform. If `action` is `nil`, the
call has no effect.

## Return Value

A view that triggers `action` before it appears.

## Discussion

The exact moment that SwiftUI calls this method
depends on the specific view type that you apply it to, but
the `action` closure completes before the first
rendered frame appears.

---

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