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# systemPrefersReducedResourceUsage

A Boolean value that indicates whether the system prefers that the app reduce its resource usage.

```
var systemPrefersReducedResourceUsage: Bool { get }
```

## Discussion

When this value is `YES`, the system has entered a state where it would prefer apps to scale back resource-intensive work.

Use this to avoid or reduce expensive work. For example:

- Gate or simplify resource-intensive UI, such as 3D or AR viewers, advanced camera modes, or live effects.
- Choose lighter-weight paths, such as lower-resolution assets or fewer simultaneous operations.
- Defer or shrink non-essential background work, such as prefetching or precomputation.

Avoid performing or scheduling expensive work in response to changes in this property, as this could worsen resource usage.

> Tip: For in-memory caching, consider using ``NSCache`` with ``NSPurgeableData``, which automatically evicts entries under system memory pressure.
> Use `systemPrefersReducedResourceUsage` for higher-level decisions that ``NSCache`` cannot make on its own.

To respond to changes in views, read the `UITraitCollection/systemPrefersReducedResourceUsage` trait.
From other contexts, observe [`systemPrefersReducedResourceUsageDidChangeNotification`](/documentation/UIKit/UIApplication/systemPrefersReducedResourceUsageDidChangeNotification) and re-read this property.

---

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