The part of the object’s visual representation that should be used to get the value for the constraint.
SDKs
- iOS 6.0+
- macOS 10.7+
- Mac Catalyst 13.0+
- tvOS 9.0+
Frameworks
- UIKit
- App
Kit
Declaration
enum Attribute : Int
EnumerationNSLayout
NSLayout
Topics
Constants
case leftThe left side of the object’s alignment rectangle.
case rightThe right side of the object’s alignment rectangle.
case topThe top of the object’s alignment rectangle.
case bottomThe bottom of the object’s alignment rectangle.
case leadingThe leading edge of the object’s alignment rectangle.
case trailingThe trailing edge of the object’s alignment rectangle.
case widthThe width of the object’s alignment rectangle.
case heightThe height of the object’s alignment rectangle.
case centerThe center along the x-axis of the object’s alignment rectangle.
case centerThe center along the y-axis of the object’s alignment rectangle.
case lastThe object’s baseline. For objects with more than one line of text, this is the baseline for the bottommost line of text.
case firstThe object’s baseline. For objects with more than one line of text, this is the baseline for the topmost line of text.
case leftThe object’s left margin. For UIView objects, the margins are defined by their layout property.
case rightThe object’s right margin. For UIView objects, the margins are defined by their layout property.
case topThe object’s top margin. For UIView objects, the margins are defined by their layout property.
case bottomThe object’s bottom margin. For UIView objects, the margins are defined by their layout property.
case leadingThe object’s leading margin. For UIView objects, the margins are defined by their layout property.
case trailingThe object’s trailing margin. For UIView objects, the margins are defined by their layout property.
case centerThe center along the x-axis between the object’s left and right margin. For UIView objects, the margins are defined by their layout property.
case centerThe center along the y-axis between the object’s top and bottom margin. For UIView objects, the margins are defined by their layout property.
case notA placeholder value that is used to indicate that the constraint’s second item and second attribute are not used in any calculations. Use this value when creating a constraint that assigns a constant to an attribute. For example, item1. If a constraint only has one item, set the second item to nil, and set the second attribute to NSLayout.