Filter Data - Swift SDK
On this page
- Overview
- About the Examples on This Page
- Realm Swift Query API
- Operators
- Comparison Operators
- Collections
- Logical Operators
- String Operators
- Geospatial Operators
- Aggregate Operators
- Set Operators
- Subqueries
- NSPredicate Queries
- Expressions
- Dot Notation
- Substitutions
- Operators
- Comparison Operators
- Logical Operators
- String Operators
- Geospatial Operators
- Aggregate Operators
- Set Operators
- Subqueries
Overview
To filter data in your realm, you can leverage Realm's query engine.
New in version 10.19.0:: Realm Swift Query API
The Realm Swift Query API offers an idiomatic way for Swift developers to query data. Use Swift-style syntax to query a realm with the benefits of auto-completion and type safety. The Realm Swift Query API does not replace the NSPredicate Query API in newer SDK versions; instead, you can use either.
For SDK versions prior to 10.19.0, or for Objective-C developers, Realm's query engine supports NSPredicate Query.
About the Examples on This Page
The examples in this page use a simple data set for a
task list app. The two Realm object types are Project
and Task
. A Task
has a name, assignee's name, and
completed flag. There is also an arbitrary number for
priority -- higher is more important -- and a count of
minutes spent working on it. Finally, a Task
can have one
or more string labels
and one or more integer ratings
.
A Project
has zero or more Tasks
.
See the schema for these two classes, Project
and
Task
, below:
// Task.h @interface Task : RLMObject @property NSString *name; @property bool isComplete; @property NSString *assignee; @property int priority; @property int progressMinutes; @end RLM_COLLECTION_TYPE(Task) // Task.m @implementation Task @end // Project.h @interface Project : RLMObject @property NSString *name; @property RLMArray<Task> *tasks; @end // Project.m @implementation Project @end
class Task: Object { var name = "" var isComplete = false var assignee: String? var priority = 0 var progressMinutes = 0 var labels: MutableSet<String> var ratings: MutableSet<Int> } class Project: Object { var name = "" var tasks: List<Task> }
You can set up the realm for these examples with the following code:
RLMRealm *realm = [RLMRealm defaultRealm]; [realm transactionWithBlock:^() { // Add projects and tasks here }]; RLMResults *tasks = [Task allObjectsInRealm:realm]; RLMResults *projects = [Project allObjectsInRealm:realm];
let realm = try! Realm() try! realm.write { // Add tasks and projects here. let project = Project() project.name = "New Project" let task = Task() task.assignee = "Alex" task.priority = 5 project.tasks.append(task) realm.add(project) // ... } let tasks = realm.objects(Task.self) let projects = realm.objects(Project.self)
Realm Swift Query API
New in version 10.19.0: For SDK versions older than 10.19.0, use the NSPredicate query API.
You can build a filter with Swift-style syntax using the .where
Realm Swift query API:
let realmSwiftQuery = projects.where { ($0.tasks.progressMinutes > 1) && ($0.tasks.assignee == "Ali") }
This query API constructs an NSPredicate to perform the query. It gives developers a type-safe idiomatic API to use directly, and abstracts away the NSPredicate construction.
The .where
API takes a callback that evaluates to true or false. The
callback receives an instance of the type being queried, and you can
leverage the compiler to statically check that you are creating valid queries
that reference valid properties.
In the examples on this page, we use the $0
shorthand to reference
the variable passed into the callback.
Operators
There are several types of operators available to query a
Realm collection. Queries
work by evaluating an operator expression for every
object in the collection being
queried. If the expression resolves to true
, Realm
Database includes the object in the results collection.
Comparison Operators
You can use Swift comparison operators with the Realm Swift
Query API (==
, !=
, >
, >=
, <
, <=
).
Example
The following example uses the query engine's comparison operators to:
Find high priority tasks by comparing the value of the
priority
property value with a threshold number, above which priority can be considered high.Find long-running tasks by seeing if the
progressMinutes
property is at or above a certain value.Find unassigned tasks by finding tasks where the
assignee
property is equal tonull
.
let highPriorityTasks = tasks.where { $0.priority > 5 } print("High-priority tasks: \(highPriorityTasks.count)") let longRunningTasks = tasks.where { $0.progressMinutes >= 120 } print("Long running tasks: \(longRunningTasks.count)") let unassignedTasks = tasks.where { $0.assignee == nil } print("Unassigned tasks: \(unassignedTasks.count)")
Collections
You can query for values within a collection using the .contains
operators.
You can search for individual values by element, or search within a range.
Operator | Description |
---|---|
.in(_ collection:) | Evaluates to true if the property referenced by the expression contains an element in the given array. |
.contains(_ element:) | Equivalent to the IN operator. Evaluates to true if the property referenced by the expression contains the value. |
.contains(_ range:) | Equivalent to the BETWEEN operator. Evaluates to true if the property referenced by the expression contains a value that is within the range. |
.containsAny(in: ) | Equivalent to the IN operator combined with the ANY operator. Evaluates to true if any elements contained in the given array are present in the collection. |
Example
Find tasks where the
labels
MutableSet collection property contains "quick win".Find tasks where the
progressMinutes
property is within a given range of minutes.
let quickWinTasks = tasks.where { $0.labels.contains("quick win") } print("Tasks labeled 'quick win': \(quickWinTasks.count)") let progressBetween30and60 = tasks.where { $0.progressMinutes.contains(30...60) } print("Tasks with progress between 30 and 60 minutes: \(progressBetween30and60.count)")
Find tasks where the labels
MutableSet collection property contains any of the elements in the given array: "quick win" or "bug".
let quickWinOrBugTasks = tasks.where { $0.labels.containsAny(in: ["quick win", "bug"]) } print("Tasks labeled 'quick win' or 'bug': \(quickWinOrBugTasks.count)")
New in version 10.23.0:: The IN
operator
The Realm Swift Query API now supports the IN
operator. Evaluates to true
if the property referenced by the expression contains the value.
Example
Find tasks assigned to specific teammates Ali or Jamie by seeing if the assignee
property is in a list of names.
let taskAssigneeInAliOrJamie = tasks.where { let assigneeNames = ["Ali", "Jamie"] return $0.assignee.in(assigneeNames) } print("Tasks IN Ali or Jamie: \(taskAssigneeInAliOrJamie.count)")
Logical Operators
You can make compound queries using Swift logical operators (&&
, !
,
||
).
Example
We can use the query language's logical operators to find
all of Ali's completed tasks. That is, we find all tasks
where the assignee
property value is equal to 'Ali' AND
the isComplete
property value is true
:
let aliComplete = tasks.where { ($0.assignee == "Ali") && ($0.isComplete == true) } print("Ali's complete tasks: \(aliComplete.count)")
String Operators
You can compare string values using these string operators. Regex-like wildcards allow more flexibility in search.
Note
You can use the following options with string operators:
.caseInsensitive
for case insensitivity.$0.name.contains("f", options: .caseInsensitive) .diacriticInsensitive
for diacritic insensitivity: Realm treats special characters as the base character (e.g.é
->e
).$0.name.contains("e", options: .diacriticInsensitive)
Operator | Description |
---|---|
.starts(with value: String) | Evaluates to true if the collection contains an element whose value begins with the specified string value. |
.contains(_ value: String) | Evaluates to true if the left-hand string expression is found anywhere in the right-hand string expression. |
.ends(with value: String) | Evaluates to true if the collection contains an element whose value ends with the specified string value. |
.like(_ value: String) | Evaluates to
For example, the wildcard string "d?g" matches "dog", "dig", and "dug", but not "ding", "dg", or "a dog". |
== | Evaluates to true if the left-hand string is lexicographically equal to the right-hand string. |
!= | Evaluates to true if the left-hand string is not lexicographically equal to the right-hand string. |
Example
The following example uses the query engine's string operators to find:
Projects with a name starting with the letter 'e'
Projects with names that contain 'ie'
Projects with an
assignee
property whose value is similar toAl?x
Projects that contain e-like characters with diacritic insensitivity
// Use the .caseInsensitive option for case-insensitivity. let startWithE = projects.where { $0.name.starts(with: "e", options: .caseInsensitive) } print("Projects that start with 'e': \(startWithE.count)") let containIe = projects.where { $0.name.contains("ie") } print("Projects that contain 'ie': \(containIe.count)") let likeWildcard = tasks.where { $0.assignee.like("Al?x") } print("Tasks with assignees like Al?x: \(likeWildcard.count)") // Use the .diacreticInsensitive option for diacritic insensitivty: contains 'e', 'E', 'é', etc. let containElike = projects.where { $0.name.contains("e", options: .diacriticInsensitive) } print("Projects that contain 'e', 'E', 'é', etc.: \(containElike.count)")
Note
String sorting and case-insensitive queries are only supported for character sets in 'Latin Basic', 'Latin Supplement', 'Latin Extended A', and 'Latin Extended B' (UTF-8 range 0-591).
Geospatial Operators
New in version 10.47.0.
Use the geoWithin
operator to query geospatial data with one of the
SDK's provided shapes:
GeoCircle
GeoBox
GeoPolygon
This operator evaluates to true
if:
An object has a geospatial data "shape" containing a
String
property with the value of Point and aList
containing a longitude/latitude pair.The longitude/latitude of the persisted object falls within the geospatial query shape.
let companiesInSmallCircle = realm.objects(Geospatial_Company.self).where { $0.location.geoWithin(smallCircle!) } print("Number of companies in small circle: \(companiesInSmallCircle.count)")
For more information about querying geospatial data, refer to Query Geospatial Data.
Aggregate Operators
You can apply an aggregate operator to a collection property of a Realm object. Aggregate operators traverse a collection and reduce it to a single value.
Operator | Description |
---|---|
.avg | Evaluates to the average value of a given numerical property across a collection. |
.count | Evaluates to the number of objects in the given collection. This
is currently only supported on to-many relationship
collections and not on lists of
primitives. In order to use .count on a list of primitives,
consider wrapping the primitives in a Realm
object. |
.max | Evaluates to the highest value of a given numerical property across a collection. |
.min | Evaluates to the lowest value of a given numerical property across a collection. |
.sum | Evaluates to the sum of a given numerical property across a collection. |
Example
We create a couple of filters to show different facets of the data:
Projects with average tasks priority above 5.
Projects that contain only low-priority tasks below 5.
Projects where all tasks are high-priority above 5.
Projects that contain more than 5 tasks.
Long running projects.
let averageTaskPriorityAbove5 = projects.where { $0.tasks.priority.avg > 5 } print("Projects with average task priority above 5: \(averageTaskPriorityAbove5.count)") let allTasksLowerPriority = projects.where { $0.tasks.priority.max < 5 } print("Projects where all tasks are lower priority: \(allTasksLowerPriority.count)") let allTasksHighPriority = projects.where { $0.tasks.priority.min > 5 } print("Projects where all tasks are high priority: \(allTasksHighPriority.count)") let moreThan5Tasks = projects.where { $0.tasks.count > 5 } print("Projects with more than 5 tasks: \(moreThan5Tasks.count)") let longRunningProjects = projects.where { $0.tasks.progressMinutes.sum > 100 } print("Long running projects: \(longRunningProjects.count)")
Set Operators
A set operator uses specific rules to determine whether to pass each input collection object to the output collection by applying a given query expression to every element of a given list property of the object.
Example
Running the following queries in projects
collections returns:
Projects where a set of string
labels
contains any of "quick win", "bug".Projects where any element in a set of integer
ratings
is greater than 3.
let projectsWithGivenLabels = projects.where { $0.tasks.labels.containsAny(in: ["quick win", "bug"]) } print("Projects with quick wins: \(projectsWithGivenLabels.count)") let projectsWithRatingsOver3 = projects.where { $0.tasks.ratings > 3 } print("Projects with any ratings over 3: \(projectsWithRatingsOver3.count)")
Subqueries
You can iterate through a collection property with another query using a
subquery. To form a subquery, you must wrap the expression in parentheses
and immediately follow it with the .count
aggregator.
(<query>).count > n
If the expression does not produce a valid subquery, you'll get an exception at runtime.
Example
Running the following query on a projects
collection returns projects
with tasks that have not been completed by a user named Alex.
let subquery = projects.where { ($0.tasks.isComplete == false && $0.tasks.assignee == "Alex").count > 0 } print("Projects with incomplete tasks assigned to Alex: \(subquery.count)")
NSPredicate Queries
You can build a filter with NSPredicate:
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"progressMinutes > %@ AND name == %@", @1, @"Ali"];
let predicate = NSPredicate(format: "progressMinutes > 1 AND name == %@", "Ali")
Expressions
Filters consist of expressions in an NSPredicate. An expression consists of one of the following:
The name (keypath) of a property of the object currently being evaluated.
An operator and up to two argument expression(s).
A value, such as a string (
'hello'
) or a number (5
).
Dot Notation
When referring to an object property, you can use dot notation to refer to child properties of that object. You can even refer to the properties of embedded objects and relationships with dot notation.
For example, consider a query on an object with a workplace
property that
refers to a Workplace object. The Workplace object has an embedded object
property, address
. You can chain dot notations to refer to the zipcode
property of that address:
workplace.address.zipcode == 10012
Substitutions
You can use the following substitutions in your predicate format strings:
%@
to specify values%K
to specify keypaths
[NSPredicate predicateWithFormat:@"%K > %@ AND %K == %@", @"progressMinutes", @1, @"name", @"Ali"];
NSPredicate(format: "%K > %@ AND %K == %@", "progressMinutes", NSNumber(1), "name", "Ali")
Operators
There are several types of operators available to filter a
Realm collection. Filters
work by evaluating an operator expression for every
object in the collection being
filtered. If the expression resolves to true
, Realm
Database includes the object in the results collection.
Comparison Operators
The most straightforward operation in a search is to compare values.
Important
Types Must Match
The type on both sides of the operator must be equivalent. For example, comparing an ObjectId with string will result in a precondition failure with a message like:
"Expected object of type object id for property 'id' on object of type 'User', but received: 11223344556677889900aabb (Invalid value)"
You can compare any numeric type with any other numeric type.
Operator | Description |
---|---|
between | Evaluates to true if the left-hand numerical or date expression is between or equal to the right-hand range. For dates, this evaluates to true if the left-hand date is within the right-hand date range. |
== , = | Evaluates to true if the left-hand expression is equal to the right-hand expression. |
> | Evaluates to true if the left-hand numerical or date expression is greater than the right-hand numerical or date expression. For dates, this evaluates to true if the left-hand date is later than the right-hand date. |
>= | Evaluates to true if the left-hand numerical or date expression is greater than or equal to the right-hand numerical or date expression. For dates, this evaluates to true if the left-hand date is later than or the same as the right-hand date. |
in | Evaluates to true if the left-hand expression is in the right-hand list or string. |
< | Evaluates to true if the left-hand numerical or date expression is less than the right-hand numerical or date expression. For dates, this evaluates to true if the left-hand date is earlier than the right-hand date. |
<= | Evaluates to true if the left-hand numeric expression is less than or equal to the right-hand numeric expression. For dates, this evaluates to true if the left-hand date is earlier than or the same as the right-hand date. |
!= , <> | Evaluates to true if the left-hand expression is not equal to the right-hand expression. |
Example
The following example uses the query engine's comparison operators to:
Find high priority tasks by comparing the value of the
priority
property value with a threshold number, above which priority can be considered high.Find long-running tasks by seeing if the
progressMinutes
property is at or above a certain value.Find unassigned tasks by finding tasks where the
assignee
property is equal tonull
.Find tasks assigned to specific teammates Ali or Jamie by seeing if the
assignee
property is in a list of names.
NSLog(@"High priority tasks: %lu", [[tasks objectsWithPredicate:[NSPredicate predicateWithFormat:@"priority > %@", @5]] count]); NSLog(@"Short running tasks: %lu", [[tasks objectsWhere:@"progressMinutes between {1, 15}"] count]); NSLog(@"Unassigned tasks: %lu", [[tasks objectsWhere:@"assignee == nil"] count]); NSLog(@"Ali or Jamie's tasks: %lu", [[tasks objectsWhere:@"assignee IN {'Ali', 'Jamie'}"] count]); NSLog(@"Tasks with progress between 30 and 60 minutes: %lu", [[tasks objectsWhere:@"progressMinutes BETWEEN {30, 60}"] count]);
let highPriorityTasks = tasks.filter("priority > 5") print("High priority tasks: \(highPriorityTasks.count)") let longRunningTasks = tasks.filter("progressMinutes > 120") print("Long running tasks: \(longRunningTasks.count)") let unassignedTasks = tasks.filter("assignee == nil") print("Unassigned tasks: \(unassignedTasks.count)") let aliOrJamiesTasks = tasks.filter("assignee IN {'Ali', 'Jamie'}") print("Ali or Jamie's tasks: \(aliOrJamiesTasks.count)") let progressBetween30and60 = tasks.filter("progressMinutes BETWEEN {30, 60}") print("Tasks with progress between 30 and 60 minutes: \(progressBetween30and60.count)")
Logical Operators
You can make compound predicates using logical operators.
Operator | Description |
---|---|
and && | Evaluates to true if both left-hand and right-hand expressions are true . |
not ! | Negates the result of the given expression. |
or || | Evaluates to true if either expression returns true . |
Example
We can use the query language's logical operators to find
all of Ali's completed tasks. That is, we find all tasks
where the assignee
property value is equal to 'Ali' AND
the isComplete
property value is true
:
NSLog(@"Ali's complete tasks: %lu", [[tasks objectsWhere:@"assignee == 'Ali' AND isComplete == true"] count]);
let aliComplete = tasks.filter("assignee == 'Ali' AND isComplete == true") print("Ali's complete tasks: \(aliComplete.count)")
String Operators
You can compare string values using these string operators. Regex-like wildcards allow more flexibility in search.
Note
You can use the following modifiers with the string operators:
[c]
for case insensitivity.[NSPredicate predicateWithFormat: @"name CONTAINS[c] 'f'"] NSPredicate(format: "name CONTAINS[c] 'f'") [d]
for diacritic insensitivity: Realm treats special characters as the base character (e.g.é
->e
).[NSPredicate predicateWithFormat: @"name CONTAINS[d] 'e'"] NSPredicate(format: "name CONTAINS[d] 'e'")
Operator | Description |
---|---|
beginsWith | Evaluates to true if the left-hand string expression begins with the right-hand string expression. This is similar to contains , but only matches if the right-hand string expression is found at the beginning of the left-hand string expression. |
contains , in | Evaluates to true if the left-hand string expression is found anywhere in the right-hand string expression. |
endsWith | Evaluates to true if the left-hand string expression ends with the right-hand string expression. This is similar to contains , but only matches if the left-hand string expression is found at the very end of the right-hand string expression. |
like | Evaluates to
For example, the wildcard string "d?g" matches "dog", "dig", and "dug", but not "ding", "dg", or "a dog". |
== , = | Evaluates to true if the left-hand string is lexicographically equal to the right-hand string. |
!= , <> | Evaluates to true if the left-hand string is not lexicographically equal to the right-hand string. |
Example
We use the query engine's string operators to find projects with a name starting with the letter 'e' and projects with names that contain 'ie':
// Use [c] for case-insensitivity. NSLog(@"Projects that start with 'e': %lu", [[projects objectsWhere:@"name BEGINSWITH[c] 'e'"] count]); NSLog(@"Projects that contain 'ie': %lu", [[projects objectsWhere:@"name CONTAINS 'ie'"] count]);
// Use [c] for case-insensitivity. let startWithE = projects.filter("name BEGINSWITH[c] 'e'") print("Projects that start with 'e': \(startWithE.count)") let containIe = projects.filter("name CONTAINS 'ie'") print("Projects that contain 'ie': \(containIe.count)") // [d] for diacritic insensitivty: contains 'e', 'E', 'é', etc. let containElike = projects.filter("name CONTAINS[cd] 'e'") print("Projects that contain 'e', 'E', 'é', etc.: \(containElike.count)")
Note
String sorting and case-insensitive queries are only supported for character sets in 'Latin Basic', 'Latin Supplement', 'Latin Extended A', and 'Latin Extended B' (UTF-8 range 0-591).
Geospatial Operators
New in version 10.47.0.
You can perform a geospatial query using the IN
operator with one
of the SDK's provided shapes:
GeoCircle
GeoBox
GeoPolygon
This operator evaluates to true
if:
An object has a geospatial data "shape" containing a
String
property with the value of Point and aList
containing a longitude/latitude pair.The longitude/latitude of the persisted object falls within the geospatial query shape.
let filterArguments = NSMutableArray() filterArguments.add(largeBox) let companiesInLargeBox = realm.objects(Geospatial_Company.self) .filter(NSPredicate(format: "location IN %@", argumentArray: filterArguments as? [Any])) print("Number of companies in large box: \(companiesInLargeBox.count)")
For more information about querying geospatial data, refer to Query Geospatial Data.
Aggregate Operators
You can apply an aggregate operator to a collection property of a Realm object. Aggregate operators traverse a collection and reduce it to a single value.
Operator | Description |
---|---|
@avg | Evaluates to the average value of a given numerical property across a collection. |
@count | Evaluates to the number of objects in the given collection. This
is currently only supported on to-many relationship
collections and not on lists of
primitives. In order to use @count on a list of primitives,
consider wrapping the primitives in a Realm
object. |
@max | Evaluates to the highest value of a given numerical property across a collection. |
@min | Evaluates to the lowest value of a given numerical property across a collection. |
@sum | Evaluates to the sum of a given numerical property across a collection. |
Example
We create a couple of filters to show different facets of the data:
Projects with average tasks priority above 5.
Long running projects.
NSLog(@"Projects with average tasks priority above 5: %lu", [[projects objectsWhere:@"tasks.@avg.priority > 5"] count]); NSLog(@"Projects where all tasks are lower priority: %lu", [[projects objectsWhere:@"tasks.@max.priority < 5"] count]); NSLog(@"Projects where all tasks are high priority: %lu", [[projects objectsWhere:@"tasks.@min.priority > 5"] count]); NSLog(@"Projects with more than 5 tasks: %lu", [[projects objectsWhere:@"tasks.@count > 5"] count]); NSLog(@"Long running projects: %lu", [[projects objectsWhere:@"tasks.@sum.progressMinutes > 100"] count]);
let averageTaskPriorityAbove5 = projects.filter("tasks.@avg.priority > 5") print("Projects with average task priority above 5: \(averageTaskPriorityAbove5.count)") let allTasksLowerPriority = projects.filter("tasks.@max.priority < 5") print("Projects where all tasks are lower priority: \(allTasksLowerPriority.count)") let allTasksHighPriority = projects.filter("tasks.@min.priority > 5") print("Projects where all tasks are high priority: \(allTasksHighPriority.count)") let moreThan5Tasks = projects.filter("tasks.@count > 5") print("Projects with more than 5 tasks: \(moreThan5Tasks.count)") let longRunningProjects = projects.filter("tasks.@sum.progressMinutes > 100") print("Long running projects: \(longRunningProjects.count)")
Set Operators
A set operator uses specific rules to determine whether to pass each input collection object to the output collection by applying a given predicate to every element of a given list property of the object.
Operator | Description |
---|---|
ALL | Returns objects where the predicate evaluates to true for all objects in the collection. |
ANY , SOME | Returns objects where the predicate evaluates to true for any objects in the collection. |
NONE | Returns objects where the predicate evaluates to false for all objects in the collection. |
Example
We use the query engine's set operators to find:
Projects with no complete tasks.
Projects with any top priority tasks.
NSLog(@"Projects with no complete tasks: %lu", [[projects objectsWhere:@"NONE tasks.isComplete == true"] count]); NSLog(@"Projects with any top priority tasks: %lu", [[projects objectsWhere:@"ANY tasks.priority == 10"] count]);
let noCompleteTasks = projects.filter("NONE tasks.isComplete == true") print("Projects with no complete tasks: \(noCompleteTasks.count)") let anyTopPriorityTasks = projects.filter("ANY tasks.priority == 10") print("Projects with any top priority tasks: \(anyTopPriorityTasks.count)")
Subqueries
You can iterate through a collection property with another query using the
SUBQUERY()
predicate function. SUBQUERY()
has the following signature:
SUBQUERY(<collection>, <variableName>, <predicate>)
collection
: the name of the list property to iterate throughvariableName
: a variable name of the current element to use in the subquerypredicate
: a string that contains the subquery predicate. You can use the variable name specified byvariableName
to refer to the currently iterated element.
Example
Running the following filter on a projects
collection returns projects
with tasks that have not been completed by a user named Alex.
NSPredicate *predicate = [NSPredicate predicateWithFormat: @"SUBQUERY(tasks, $task, $task.isComplete == %@ AND $task.assignee == %@).@count > 0", @NO, @"Alex"]; NSLog(@"Projects with incomplete tasks assigned to Alex: %lu", [[projects objectsWithPredicate:predicate] count]);
let predicate = NSPredicate( format: "SUBQUERY(tasks, $task, $task.isComplete == false AND $task.assignee == %@).@count > 0", "Alex") print("Projects with incomplete tasks assigned to Alex: \(projects.filter(predicate).count)")