---
title: critical
framework: dispatch
role: symbol
role_heading: Type Property
path: dispatch/dispatchsource/memorypressureevent/critical
---

# critical

An event indicating that the system memory pressure condition changed to critical.

## Declaration

```swift
static let critical: DispatchSource.MemoryPressureEvent
```

## See Also

### Memory Pressure Event Flags

- [all](dispatch/dispatchsource/memorypressureevent/all.md)
- [normal](dispatch/dispatchsource/memorypressureevent/normal.md)
- [warning](dispatch/dispatchsource/memorypressureevent/warning.md)