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SDK de Dispositivo Atlas

Kit de desarrollo de software de Swift

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Filtrar datos - Swift SDK

Los SDK de dispositivos Atlas están obsoletos. Consulte deprecation page for details.

Overview

Para filtrar datos en su ámbito, puede aprovechar el motor de consulta de Realm.

Novedades de la versión 10.19.0: API de consulta Swift de Realm

La La API de consulta de Realm Swift ofrece a los desarrolladores de Swift una forma idiomática de consultar datos. Utilice la sintaxis de estilo Swift para consultar un realm con las ventajas del autocompletado y la seguridad de tipos. La API de consulta de Realm Swift no reemplaza a la API de consulta NSPredicate en las versiones más recientes del SDK; puede usar cualquiera de las dos.

Para versiones del SDK anteriores a la 10.19.0, o para desarrolladores de Objective-C, el motor de query de Realm admite query de NSPredicate.

About the Examples on This Page

Los ejemplos de esta página utilizan un conjunto de datos simple para una aplicación de lista de tareas. Los dos tipos de objetos Realm son Project y Task. Un Task tiene un nombre, el nombre del asignado y un indicador de finalización. También hay un número arbitrario para la prioridad (cuanto más alto, más importante) y un recuento de minutos dedicados a trabajar en él. Finalmente, un Task puede tener una o más cadenas labels y uno o más enteros ratings.

Un Project tiene cero o más 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 {
    @Persisted var name = ""
    @Persisted var isComplete = false
    @Persisted var assignee: String?
    @Persisted var priority = 0
    @Persisted var progressMinutes = 0
    @Persisted var labels: MutableSet<String>
    @Persisted var ratings: MutableSet<Int>
}
class Project: Object {
    @Persisted var name = ""
    @Persisted 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")
}

Esta API de query construye un NSPredicate para realizar la query. Ofrece a los desarrolladores una API tipada, idiomática y segura que pueden usar directamente, y abstrae la construcción de NSPredicate.

La API .where recibe una devolución de llamada que evalúa como verdadera o falsa. Esta devolución de llamada recibe una instancia del tipo consultado, y se puede usar el compilador para comprobar estáticamente que se están creando consultas válidas que hacen referencia a propiedades válidas.

In the examples on this page, we use the $0 shorthand to reference the variable passed into the callback.

Operadores

Hay varios tipos de operadores disponibles para consultar una colección de Realm. Las queries funcionan evaluando una expresión de operador para cada objeto en la colección consultada. Si la expresión se resuelve en true, Realm base de datos incluye el objeto en la colección de resultados.

Operadores de comparación

You can use Swift comparison operators with the Realm Swift Query API (==, !=, >, >=, <, <=).

Ejemplo

The following example uses the query engine's comparison operators to:

Encuentre tareas de alta prioridad comparando el valor de la propiedad priority con un número umbral, por encima del cual la prioridad puede considerarse alta.
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 to null.

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)")

Colecciones

Puedes consultar valores dentro de una colección usando los operadores .contains. Puedes buscar valores individuales por elemento o dentro de un rango.

Operador	Descripción
`.in(_ collection:)`	Se evalúa como `true` si la propiedad a la que hace referencia la expresión contiene un elemento en la matriz dada.
`.contains(_ element:)`	Equivalente al operador `IN`. Se evalúa como `true` si la propiedad referenciada por la expresión contiene el valor.
`.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.

Ejemplo

Buscar tareas donde la propiedad MutableSet de la colección "labels" contenga "quick win".
Encuentra tareas donde la propiedad progressMinutes se encuentre en un rango determinado de minutos.

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)")

Busque tareas donde la propiedad de colección MutableSet labels contenga cualquiera de los elementos en la matriz dada: "quick win" o "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

La API de consulta de Realm Swift ahora admite el operador IN. Se evalúa como true si la propiedad referenciada por la expresión contiene el valor.

Ejemplo

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)")

Operadores lógicos

You can make compound queries using Swift logical operators (&&, !, ||).

Ejemplo

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)")

Operadores de String

You can compare string values using these string operators. Regex-like wildcards allow more flexibility in search.

Nota

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)
```

Operador	Descripción
`.starts(with value: String)`	Se evalúa como `true` si la colección contiene un elemento cuyo valor comienza con el valor de string especificado.
`.contains(_ value: String)`	Evalúa como `true` si la expresión de string a la izquierda se encuentra en cualquier parte de la expresión de string a la derecha.
`.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 `true` if the left-hand string expression matches the right-hand string wildcard string expression. A wildcard string expression is a string that uses normal characters with two special wildcard characters: The `*` wildcard matches zero or more of any character The `?` wildcard matches any character. 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.
`!=`	Se evalúa como `true` si la cadena de la izquierda no es lexicográficamente igual a la cadena de la derecha.

Ejemplo

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 to Al?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)")

Nota

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).

Operadores geoespaciales

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 a List 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)")

Para obtener más información sobre cómo consultar datos geoespaciales, consulte Consultar datos geoespaciales.

Aggregate Operators

Se puede aplicar un operador de agregación a una propiedad de colección de un objeto Realm. Los operadores de agregación recorren una colección y la reducen a un único valor.

Operador	Descripción
`.avg`	Se evalúa como el valor promedio de una propiedad numérica dada en una colección.
`.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.

Ejemplo

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.
Proyectos que contienen más de 5 tareas.
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)")

Operadores de conjuntos

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.

Ejemplo

Running the following queries in projects collections returns:

Proyectos donde un conjunto de strings labels contiene cualquier término de "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

Puede iterar a través de una propiedad de colección con otra consulta mediante una subconsulta. Para formar una subconsulta, debe encerrar la expresión entre paréntesis e inmediatamente después el agregador .count.

(<query>).count > n

If the expression does not produce a valid subquery, you'll get an exception at runtime.

Ejemplo

Ejecutar la siguiente query en una colección projects devuelve proyectos con tareas que no han sido completadas por un usuario llamado 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)")

Consultas NSPredicate

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")

Expresiones

Los filtros consisten en expresiones en un NSPredicate. Una expresión consta de uno de los siguientes:

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).

Notación de puntos

Al referirse a una propiedad de un objeto, se puede usar la notación de puntos para referirse a sus propiedades secundarias. Incluso se puede usar la notación de puntos para referirse a las propiedades de objetos incrustados y relaciones.

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

Puedes utilizar las siguientes sustituciones en tus cadenas de formato de predicado:

%@ to specify values
%K para especificar rutas de acceso clave

[NSPredicate predicateWithFormat:@"%K > %@ AND %K == %@", @"progressMinutes", @1, @"name", @"Ali"];

NSPredicate(format: "%K > %@ AND %K == %@", "progressMinutes", NSNumber(1), "name", "Ali")

Operadores

Hay varios tipos de operadores disponibles para filtrar una colección de Realm. Los filtros funcionan evaluando una expresión de operador para cada objeto de la colección que se filtra. Si la expresión se resuelve como true, Realm Database incluye el objeto en la colección de resultados.

Operadores de comparación

The most straightforward operation in a search is to compare values.

Importante

Types Must Match

El tipo en ambos lados del operador debe ser equivalente. Por ejemplo, comparar un ObjectId con string resultará en una falla de precondición con un mensaje similar a:

"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.

Operador	Descripción
`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.
`<`	Devuelve `true` si la expresión numérica o de fecha de la izquierda es menor que la expresión numérica o de fecha de la derecha. Para fechas, esto da como resultado `true` si la fecha de la izquierda es anterior a la fecha de la derecha.
`<=`	Se evalúa como `true` si la expresión numérica de la izquierda es menor o igual que la de la derecha. Para las fechas, se evalúa como `true` si la fecha de la izquierda es anterior o igual a la de la derecha.
`!=`, `<>`	Evaluates to `true` if the left-hand expression is not equal to the right-hand expression.

Ejemplo

The following example uses the query engine's comparison operators to:

Encuentre tareas de alta prioridad comparando el valor de la propiedad priority con un número umbral, por encima del cual la prioridad puede considerarse alta.
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 to null.
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)")

Operadores lógicos

You can make compound predicates using logical operators.

Operador	Descripción
`and` `&&`	Se evalúa como `true` si las expresiones de la izquierda y la derecha son `true`.
`not` `!`	Negates the result of the given expression.
`or` `\|\|`	Evaluates to `true` if either expression returns `true`.

Ejemplo

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)")

Operadores de String

You can compare string values using these string operators. Regex-like wildcards allow more flexibility in search.

Nota

Puede utilizar los siguientes modificadores con los operadores de cadena:

[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'")

Operador	Descripción
`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`	Evalúa como `true` si la expresión de string a la izquierda se encuentra en cualquier parte de la expresión de string a la derecha.
`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 `true` if the left-hand string expression matches the right-hand string wildcard string expression. A wildcard string expression is a string that uses normal characters with two special wildcard characters: The `*` wildcard matches zero or more of any character The `?` wildcard matches any character. 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.
`!=`, `<>`	Se evalúa como `true` si la cadena de la izquierda no es lexicográficamente igual a la cadena de la derecha.

Ejemplo

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)")

Nota

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).

Operadores geoespaciales

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 a List 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)")

Para obtener más información sobre cómo consultar datos geoespaciales, consulte Consultar datos geoespaciales.

Aggregate Operators

Se puede aplicar un operador de agregación a una propiedad de colección de un objeto Realm. Los operadores de agregación recorren una colección y la reducen a un único valor.

Operador	Descripción
`@avg`	Se evalúa como el valor promedio de una propiedad numérica dada en una colección.
`@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.

Ejemplo

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)")

Operadores de conjuntos

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.

Operador	Descripción
`ALL`	Devuelve objetos donde el predicado evalúa como `true` para todos los objetos de la colección.
`ANY`, `SOME`	Devuelve objetos donde el predicado evalúa a `true` para cualquier objeto de la colección.
`NONE`	Returns objects where the predicate evaluates to false for all objects in the collection.

Ejemplo

Utilizamos los operadores de conjunto del motor de consulta para encontrar:

Projects with no complete tasks.
Proyectos con tareas de máxima prioridad.

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 through
variableName: un nombre de variable del elemento actual a utilizar en la subconsulta
predicate: a string that contains the subquery predicate. You can use the variable name specified by variableName to refer to the currently iterated element.

Ejemplo

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)")

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