# linearGravityField(direction:) Creates and returns a field behavior object that models a linear gravitational force. ``` class func linearGravityField(direction: CGVector) -> Self ``` ## Parameters `direction` The vector indicating the direction of the gravitational force. You can change this value later by modifying the [`direction`](/documentation/UIKit/UIFieldBehavior/direction) property. ## Return Value A field behavior object that applies a directional gravitation force to items with mass. ## Discussion This field creates a directional gravitational force that applies uniformly to all dynamic items with mass. When setting the [`strength`](/documentation/UIKit/UIFieldBehavior/strength) of the field, positive values attract items in the direction of the vector and negative values repel items. The force on a given item can be determined by the equation `F = ma`, where force equals the mass of the item multiplied by the acceleration imposed by the gravitational field, which with this type of field is constant. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)