---
title: invalidateFlowLayoutDelegateMetrics
framework: appkit
role: symbol
role_heading: Instance Property
path: appkit/nscollectionviewflowlayoutinvalidationcontext/invalidateflowlayoutdelegatemetrics
---

# invalidateFlowLayoutDelegateMetrics

A Boolean value indicating whether the flow layout object should fetch new size information from its delegate.

## Declaration

```swift
var invalidateFlowLayoutDelegateMetrics: Bool { get set }
```

## Discussion

Discussion As part of the invalidation process, the flow layout object normally asks its delegate to provide size information for the items in the flow layout. This behavior is necessary when the size of the items can change because it ensures that the corresponding layout attributes are always updated. However, if you know that the size of items has not changed, you can set this property to false. Doing so causes the flow layout to use its existing size information rather than querying the delegate, which saves time. The default value of this property is true, which causes the flow layout object to query the delegate for new size information.

## See Also

### Invalidating the Flow Layout

- [invalidateFlowLayoutAttributes](appkit/nscollectionviewflowlayoutinvalidationcontext/invalidateflowlayoutattributes.md)