Struct NSExpressionDescription

#[repr(C)]
pub struct NSExpressionDescription { /* private fields */ }

Available on crate features NSExpressionDescription and NSPropertyDescription only.

Apple’s documentation

Implementations

impl NSExpressionDescription

pub unsafe fn expression(&self) -> Option<Retained<NSExpression>>

pub unsafe fn setExpression(&self, expression: Option<&NSExpression>)

Setter for expression.

pub unsafe fn expressionResultType(&self) -> NSAttributeType

Available on crate feature NSAttributeDescription only.

pub unsafe fn setExpressionResultType( &self, expression_result_type: NSAttributeType, )

Available on crate feature NSAttributeDescription only.

Setter for expressionResultType.

impl NSExpressionDescription

Methods declared on superclass NSObject.

pub unsafe fn init(this: Allocated<Self>) -> Retained<Self>

pub unsafe fn new() -> Retained<Self>

Methods from Deref<Target = NSPropertyDescription>

pub unsafe fn entity(&self) -> Retained<NSEntityDescription>

Available on crate feature NSEntityDescription only.

pub unsafe fn name(&self) -> Retained<NSString>

pub unsafe fn setName(&self, name: &NSString)

Setter for name.

pub unsafe fn isOptional(&self) -> bool

pub unsafe fn setOptional(&self, optional: bool)

Setter for isOptional.

pub unsafe fn isTransient(&self) -> bool

pub unsafe fn setTransient(&self, transient: bool)

Setter for isTransient.

pub unsafe fn validationPredicates(&self) -> Retained<NSArray<NSPredicate>>

pub unsafe fn validationWarnings(&self) -> Retained<NSArray>

pub unsafe fn setValidationPredicates_withValidationWarnings( &self, validation_predicates: Option<&NSArray<NSPredicate>>, validation_warnings: Option<&NSArray<NSString>>, )

pub unsafe fn userInfo(&self) -> Option<Retained<NSDictionary>>

pub unsafe fn setUserInfo(&self, user_info: Option<&NSDictionary>)

Setter for userInfo.

pub unsafe fn isIndexed(&self) -> bool

👎Deprecated: Use NSEntityDescription.indexes instead

pub unsafe fn setIndexed(&self, indexed: bool)

👎Deprecated: Use NSEntityDescription.indexes instead

Setter for isIndexed.

pub unsafe fn versionHash(&self) -> Retained<NSData>

pub unsafe fn versionHashModifier(&self) -> Option<Retained<NSString>>

pub unsafe fn setVersionHashModifier( &self, version_hash_modifier: Option<&NSString>, )

Setter for versionHashModifier.

pub unsafe fn isIndexedBySpotlight(&self) -> bool

pub unsafe fn setIndexedBySpotlight(&self, indexed_by_spotlight: bool)

Setter for isIndexedBySpotlight.

pub unsafe fn isStoredInExternalRecord(&self) -> bool

👎Deprecated: Spotlight integration is deprecated. Use CoreSpotlight integration instead.

pub unsafe fn setStoredInExternalRecord(&self, stored_in_external_record: bool)

👎Deprecated: Spotlight integration is deprecated. Use CoreSpotlight integration instead.

Setter for isStoredInExternalRecord.

pub unsafe fn renamingIdentifier(&self) -> Option<Retained<NSString>>

pub unsafe fn setRenamingIdentifier( &self, renaming_identifier: Option<&NSString>, )

Setter for renamingIdentifier.

Methods from Deref<Target = NSObject>

pub fn doesNotRecognizeSelector(&self, sel: Sel) -> !

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>

pub fn class(&self) -> &'static AnyClass

Dynamically find the class of this object.

Panics

May panic if the object is invalid (which may be the case for objects returned from unavailable init/new methods).

Example

Check that an instance of NSObject has the precise class NSObject.

use objc2::ClassType;
use objc2::runtime::NSObject;

let obj = NSObject::new();
assert_eq!(obj.class(), NSObject::class());

pub unsafe fn get_ivar<T>(&self, name: &str) -> &T

where T: Encode,

👎Deprecated: this is difficult to use correctly, use Ivar::load instead.

Use Ivar::load instead.

Safety

The object must have an instance variable with the given name, and it must be of type T.

See Ivar::load_ptr for details surrounding this.

pub fn downcast_ref<T>(&self) -> Option<&T>

where T: DowncastTarget,

Attempt to downcast the object to a class of type T.

This is the reference-variant. Use Retained::downcast if you want to convert a retained object to another type.

Mutable classes

Some classes have immutable and mutable variants, such as NSString and NSMutableString.

When some Objective-C API signature says it gives you an immutable class, it generally expects you to not mutate that, even though it may technically be mutable “under the hood”.

So using this method to convert a NSString to a NSMutableString, while not unsound, is generally frowned upon unless you created the string yourself, or the API explicitly documents the string to be mutable.

See Apple’s documentation on mutability and on isKindOfClass: for more details.

Generic classes

Objective-C generics are called “lightweight generics”, and that’s because they aren’t exposed in the runtime. This makes it impossible to safely downcast to generic collections, so this is disallowed by this method.

You can, however, safely downcast to generic collections where all the type-parameters are AnyObject.

Panics

This works internally by calling isKindOfClass:. That means that the object must have the instance method of that name, and an exception will be thrown (if CoreFoundation is linked) or the process will abort if that is not the case. In the vast majority of cases, you don’t need to worry about this, since both root objects NSObject and NSProxy implement this method.

Examples

Cast an NSString back and forth from NSObject.

use objc2::rc::Retained;
use objc2_foundation::{NSObject, NSString};

let obj: Retained<NSObject> = NSString::new().into_super();
let string = obj.downcast_ref::<NSString>().unwrap();
// Or with `downcast`, if we do not need the object afterwards
let string = obj.downcast::<NSString>().unwrap();

Try (and fail) to cast an NSObject to an NSString.

use objc2_foundation::{NSObject, NSString};

let obj = NSObject::new();
assert!(obj.downcast_ref::<NSString>().is_none());

Try to cast to an array of strings.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);
// This is invalid and doesn't type check.
let arr = arr.downcast_ref::<NSArray<NSString>>();

This fails to compile, since it would require enumerating over the array to ensure that each element is of the desired type, which is a performance pitfall.

Downcast when processing each element instead.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);

for elem in arr {
    if let Some(data) = elem.downcast_ref::<NSString>() {
        // handle `data`
    }
}

Trait Implementations

impl AsRef<AnyObject> for NSExpressionDescription

fn as_ref(&self) -> &AnyObject

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<NSExpressionDescription> for NSExpressionDescription

fn as_ref(&self) -> &Self

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<NSObject> for NSExpressionDescription

fn as_ref(&self) -> &NSObject

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<NSPropertyDescription> for NSExpressionDescription

fn as_ref(&self) -> &NSPropertyDescription

Converts this type into a shared reference of the (usually inferred) input type.

impl Borrow<AnyObject> for NSExpressionDescription

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl Borrow<NSObject> for NSExpressionDescription

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl Borrow<NSPropertyDescription> for NSExpressionDescription

fn borrow(&self) -> &NSPropertyDescription

Immutably borrows from an owned value.

impl ClassType for NSExpressionDescription

const NAME: &'static str = "NSExpressionDescription"

The name of the Objective-C class that this type represents.

type Super = NSPropertyDescription

The superclass of this class.

type ThreadKind = <<NSExpressionDescription as ClassType>::Super as ClassType>::ThreadKind

Whether the type can be used from any thread, or from only the main thread.

fn class() -> &'static AnyClass

Get a reference to the Objective-C class that this type represents.

fn as_super(&self) -> &Self::Super

Get an immutable reference to the superclass.

impl CopyingHelper for NSExpressionDescription

type Result = NSExpressionDescription

The immutable counterpart of the type, or Self if the type has no immutable counterpart.

impl Debug for NSExpressionDescription

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Deref for NSExpressionDescription

type Target = NSPropertyDescription

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl Hash for NSExpressionDescription

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Message for NSExpressionDescription

fn retain(&self) -> Retained<Self>

where Self: Sized,

Increment the reference count of the receiver.

impl NSCoding for NSExpressionDescription

unsafe fn encodeWithCoder(&self, coder: &NSCoder)

where Self: Sized + Message,

unsafe fn initWithCoder( this: Allocated<Self>, coder: &NSCoder, ) -> Option<Retained<Self>>

where Self: Sized + Message,

impl NSCopying for NSExpressionDescription

fn copy(&self) -> Retained<Self::Result>

where Self: Sized + Message + CopyingHelper,

Returns a new instance that’s a copy of the receiver.

unsafe fn copyWithZone(&self, zone: *mut NSZone) -> Retained<Self::Result>

where Self: Sized + Message + CopyingHelper,

Returns a new instance that’s a copy of the receiver.

impl NSObjectProtocol for NSExpressionDescription

fn isEqual(&self, other: Option<&AnyObject>) -> bool

where Self: Sized + Message,

Check whether the object is equal to an arbitrary other object.

fn hash(&self) -> usize

where Self: Sized + Message,

An integer that can be used as a table address in a hash table structure.

fn isKindOfClass(&self, cls: &AnyClass) -> bool

where Self: Sized + Message,

Check if the object is an instance of the class, or one of its subclasses.

fn is_kind_of<T>(&self) -> bool

where T: ClassType, Self: Sized + Message,

👎Deprecated: use isKindOfClass directly, or cast your objects with AnyObject::downcast_ref

Check if the object is an instance of the class type, or one of its subclasses.

fn isMemberOfClass(&self, cls: &AnyClass) -> bool

where Self: Sized + Message,

Check if the object is an instance of a specific class, without checking subclasses.

fn respondsToSelector(&self, aSelector: Sel) -> bool

where Self: Sized + Message,

Check whether the object implements or inherits a method with the given selector.

fn conformsToProtocol(&self, aProtocol: &AnyProtocol) -> bool

where Self: Sized + Message,

Check whether the object conforms to a given protocol.

fn description(&self) -> Retained<NSObject>

where Self: Sized + Message,

A textual representation of the object.

fn debugDescription(&self) -> Retained<NSObject>

where Self: Sized + Message,

A textual representation of the object to use when debugging.

fn isProxy(&self) -> bool

where Self: Sized + Message,

Check whether the receiver is a subclass of the NSProxy root class instead of the usual NSObject.

fn retainCount(&self) -> usize

where Self: Sized + Message,

The reference count of the object.

impl PartialEq for NSExpressionDescription

fn eq(&self, other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl RefEncode for NSExpressionDescription

const ENCODING_REF: Encoding = <NSPropertyDescription as ::objc2::RefEncode>::ENCODING_REF

The Objective-C type-encoding for a reference of this type.

impl DowncastTarget for NSExpressionDescription

impl Eq for NSExpressionDescription