# NSPredicateEditorRowTemplate A template that describes available predicates and how to display them. ``` class NSPredicateEditorRowTemplate ``` ## Overview You can create instances of `NSPredicateEditorRowTemplate` programmatically or in Interface Builder. By default, a noncompound row template has three views: a popup (or static text field) on the left, a popup or static text field for operators, and either a popup or other view on the right.  You can subclass `NSPredicateEditorRowTemplate` to create a row template with different numbers or types of views. `NSPredicateEditorRowTemplate` is a concrete class, but it has five primitive methods that are called by [`NSPredicateEditor`](/documentation/AppKit/NSPredicateEditor): [`templateViews`](/documentation/AppKit/NSPredicateEditorRowTemplate/templateViews), [`match(for:)`](/documentation/AppKit/NSPredicateEditorRowTemplate/match(for:)), [`setPredicate(_:)`](/documentation/AppKit/NSPredicateEditorRowTemplate/setPredicate(_:)), [`displayableSubpredicates(of:)`](/documentation/AppKit/NSPredicateEditorRowTemplate/displayableSubpredicates(of:)), and [`predicate(withSubpredicates:)`](/documentation/AppKit/NSPredicateEditorRowTemplate/predicate(withSubpredicates:)). `NSPredicateEditorRowTemplate` implements all of these methods, but you can override them for custom templates. The primitive methods are used by an instance of `NSPredicateEditor` as follows. First, an instance of `NSPredicateEditor` is created, and some row templates are set on it—either through a nib file or programmatically. The first thing predicate editor does is ask each of the templates for their views, using [`templateViews`](/documentation/AppKit/NSPredicateEditorRowTemplate/templateViews). After setting up the predicate editor, you typically send it a [`objectValue`](/documentation/AppKit/NSControl/objectValue) message to restore a saved predicate. `NSPredicateEditor` needs to determine which of its templates should display each predicate in the predicate tree. It does this by sending each of its row templates a [`match(for:)`](/documentation/AppKit/NSPredicateEditorRowTemplate/match(for:)) message and choosing the one that returns the highest value. After finding the best match for a predicate, `NSPredicateEditor` copies that template to get fresh views, inserts them into the proper row, and then sets the predicate on the template using [`setPredicate(_:)`](/documentation/AppKit/NSPredicateEditorRowTemplate/setPredicate(_:)). Within that method, the `NSPredicateEditorRowTemplate` object must set its views’ values to represent that predicate. `NSPredicateEditorRowTemplate` next asks the template for the “displayable sub-predicates” of the predicate by sending a [`displayableSubpredicates(of:)`](/documentation/AppKit/NSPredicateEditorRowTemplate/displayableSubpredicates(of:)) message. If a template represents a predicate in its entirety, or if the predicate has no subpredicates, it can return `nil` for this.  Otherwise, it should return a list of predicates to be made into sub-rows of that template’s row. The whole process repeats for each sub-predicate. At this point, the user sees the predicate that was saved.  If the user then makes some changes to the views of the templates, this causes `NSPredicateEditor` to recompute its predicate by asking each of the templates to return the predicate represented by the new view values, passing in the subpredicates represented by the sub-rows (an empty array if there are none, or `nil` if they aren’t supported by that predicate type): [`predicate(withSubpredicates:)`](/documentation/AppKit/NSPredicateEditorRowTemplate/predicate(withSubpredicates:)) ## Topics ### Initializing a Template [`init(leftExpressions:rightExpressions:modifier:operators:options:)`](/documentation/AppKit/NSPredicateEditorRowTemplate/init(leftExpressions:rightExpressions:modifier:operators:options:)) Initializes and returns a “pop-up-pop-up-pop-up”–style row template. [`init(leftExpressions:rightExpressionAttributeType:modifier:operators:options:)`](/documentation/AppKit/NSPredicateEditorRowTemplate/init(leftExpressions:rightExpressionAttributeType:modifier:operators:options:)) Initializes and returns a “pop-up-pop-up-view”–style row template. [`init(compoundTypes:)`](/documentation/AppKit/NSPredicateEditorRowTemplate/init(compoundTypes:)) Initializes and returns a row template suitable for displaying compound predicates. ### Core Data Integration [`templates(withAttributeKeyPaths:in:)`](/documentation/AppKit/NSPredicateEditorRowTemplate/templates(withAttributeKeyPaths:in:)) Returns an array of predicate templates for the given attribute key paths for a given entity. ### Primitive Methods [`match(for:)`](/documentation/AppKit/NSPredicateEditorRowTemplate/match(for:)) Returns a positive number if the receiver can represent a given predicate, and `0` if it cannot. [`templateViews`](/documentation/AppKit/NSPredicateEditorRowTemplate/templateViews) Returns the views that display this template’s predicate. [`setPredicate(_:)`](/documentation/AppKit/NSPredicateEditorRowTemplate/setPredicate(_:)) Sets the value of the views according to the given predicate. [`displayableSubpredicates(of:)`](/documentation/AppKit/NSPredicateEditorRowTemplate/displayableSubpredicates(of:)) Returns the subpredicates that should be made sub-rows of a given predicate. [`predicate(withSubpredicates:)`](/documentation/AppKit/NSPredicateEditorRowTemplate/predicate(withSubpredicates:)) Returns the predicate represented by the receiver’s views’ values and the given sub-predicates. ### Information About a Row Template [`leftExpressions`](/documentation/AppKit/NSPredicateEditorRowTemplate/leftExpressions) Returns the left hand expressions for the receiver. [`rightExpressions`](/documentation/AppKit/NSPredicateEditorRowTemplate/rightExpressions) Returns the right hand expressions for the receiver. [`compoundTypes`](/documentation/AppKit/NSPredicateEditorRowTemplate/compoundTypes) Returns the compound predicate types. [`modifier`](/documentation/AppKit/NSPredicateEditorRowTemplate/modifier) Returns the comparison predicate modifier for the receiver. [`operators`](/documentation/AppKit/NSPredicateEditorRowTemplate/operators) Returns the array of comparison predicate operators. [`options`](/documentation/AppKit/NSPredicateEditorRowTemplate/options) Returns the comparison predicate options. [`rightExpressionAttributeType`](/documentation/AppKit/NSPredicateEditorRowTemplate/rightExpressionAttributeType) Returns the attribute type of the receiver’s right expression. --- Copyright © 2026 Apple Inc. 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