Mac Developer Library


Quartz Core Framework Reference CAConstraintLayoutManager Class Reference

Deployment Target:

On This Page


The CAConstraintLayoutManager class provides a constraint-based layout manager. You use the shared instance of this object by assigning it to the layoutManager property of any layer objects to which you have added constraints. During a layout update, Core Animation uses the layout manager to update the size and position of the sublayers based on the registered set of constraints.

Constraints let you define a set of geometric relationships between a layer and its sibling layers or between a layer and its superlayer. These relationships are expressed using constraint objects, which are instances of the CAConstraint class. When creating constraints, you can reference a layer by name using that object’s name property. You can also use the special name superlayer to refer to the layer's superlayer.

This class is not meant to be subclassed.

  • Returns the shared layout manager object.



    + (instancetype)layoutManager

    Return Value

    The shared layout manager object.


    You can assign the returned object to any layers that manage layout using constraints.


    Available in OS X v10.5 and later.