---
title: fieldBitMask
framework: spritekit
role: symbol
role_heading: Instance Property
path: spritekit/skemitternode/fieldbitmask
---

# fieldBitMask

A mask that defines which categories of physics fields can exert forces on the particles.

## Declaration

```swift
var fieldBitMask: UInt32 { get set }
```

## Discussion

Discussion When a particle is inside the region of a SKFieldNode object, that field node’s categoryBitMask property is compared to the emitter’s fieldBitMask property by performing a logical AND operation. If the result is a non-zero value, then the field node’s effect is applied to the particle as if it had a physics body. The physics body is assumed to have a mass of 1.0 and a charge of 1.0 The default value is 0x00000000 (all bits cleared).