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  "title" : "control(_:didFailToFormatString:errorDescription:)"
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# control(_:didFailToFormatString:errorDescription:)

Invoked when the formatter for the cell belonging to the specified control cannot convert a string to an underlying object.

```
@MainActor optional func control(_ control: NSControl, didFailToFormatString string: String, errorDescription error: String?) -> Bool
```

## Parameters

`control`

The control whose cell could not convert the string.

`string`

The string that could not be converted.

`error`

A localized, user-presentable string that explains why the conversion failed.

## Return Value

<doc://com.apple.documentation/documentation/Swift/true> if the value in the string parameter should be accepted as is; otherwise, <doc://com.apple.documentation/documentation/Swift/false> if the value in the parameter should be rejected.

## Discussion

Your implementation of this method should evaluate the error or query the user an appropriate value indicating whether the string should be accepted or rejected.

## See Also

  <doc://com.apple.documentation/documentation/Foundation/Formatter/getObjectValue(_:for:errorDescription:)>


---

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