Struct NSExpression 

pub struct NSExpression { /* private fields */ }

Available on crate feature NSExpression only.

Apple’s documentation

Implementations

impl NSExpression

pub unsafe fn expressionWithFormat_argumentArray( expression_format: &NSString, arguments: &NSArray, ) -> Retained<NSExpression>

Available on crate features NSArray and NSString only.

Safety

arguments generic should be of the correct type.

pub unsafe fn expressionForConstantValue( obj: Option<&AnyObject>, ) -> Retained<NSExpression>

Safety

obj should be of the correct type.

pub fn expressionForEvaluatedObject() -> Retained<NSExpression>

pub fn expressionForVariable(string: &NSString) -> Retained<NSExpression>

Available on crate feature NSString only.

pub fn expressionForKeyPath(key_path: &NSString) -> Retained<NSExpression>

Available on crate feature NSString only.

pub unsafe fn expressionForFunction_arguments( name: &NSString, parameters: &NSArray, ) -> Retained<NSExpression>

Available on crate features NSArray and NSString only.

Safety

parameters generic should be of the correct type.

pub fn expressionForAggregate( subexpressions: &NSArray<NSExpression>, ) -> Retained<NSExpression>

Available on crate feature NSArray only.

pub fn expressionForUnionSet_with( left: &NSExpression, right: &NSExpression, ) -> Retained<NSExpression>

pub fn expressionForIntersectSet_with( left: &NSExpression, right: &NSExpression, ) -> Retained<NSExpression>

pub fn expressionForMinusSet_with( left: &NSExpression, right: &NSExpression, ) -> Retained<NSExpression>

pub fn expressionForSubquery_usingIteratorVariable_predicate( expression: &NSExpression, variable: &NSString, predicate: &NSPredicate, ) -> Retained<NSExpression>

Available on crate features NSPredicate and NSString only.

pub unsafe fn expressionForFunction_selectorName_arguments( target: &NSExpression, name: &NSString, parameters: Option<&NSArray>, ) -> Retained<NSExpression>

Available on crate features NSArray and NSString only.

Safety

parameters generic should be of the correct type.

pub fn expressionForAnyKey() -> Retained<NSExpression>

pub unsafe fn expressionForBlock_arguments( block: &DynBlock<dyn Fn(*mut AnyObject, NonNull<NSArray<NSExpression>>, *mut NSMutableDictionary) -> NonNull<AnyObject>>, arguments: Option<&NSArray<NSExpression>>, ) -> Retained<NSExpression>

Available on crate features NSArray and NSDictionary and block2 only.

Safety

• block block’s return must be a valid pointer.
• block block’s argument 3 generic should be of the correct type.

pub fn expressionForConditional_trueExpression_falseExpression( predicate: &NSPredicate, true_expression: &NSExpression, false_expression: &NSExpression, ) -> Retained<NSExpression>

Available on crate feature NSPredicate only.

pub fn initWithExpressionType( this: Allocated<Self>, type: NSExpressionType, ) -> Retained<Self>

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

Available on crate feature NSCoder only.

Safety

coder possibly has further requirements.

pub fn expressionType(&self) -> NSExpressionType

pub fn constantValue(&self) -> Option<Retained<AnyObject>>

pub fn keyPath(&self) -> Retained<NSString>

Available on crate feature NSString only.

pub fn function(&self) -> Retained<NSString>

Available on crate feature NSString only.

pub fn variable(&self) -> Retained<NSString>

Available on crate feature NSString only.

pub fn operand(&self) -> Retained<NSExpression>

pub fn arguments(&self) -> Option<Retained<NSArray<NSExpression>>>

Available on crate feature NSArray only.

pub fn collection(&self) -> Retained<AnyObject>

pub fn predicate(&self) -> Retained<NSPredicate>

Available on crate feature NSPredicate only.

pub fn leftExpression(&self) -> Retained<NSExpression>

pub fn rightExpression(&self) -> Retained<NSExpression>

pub fn trueExpression(&self) -> Retained<NSExpression>

pub fn falseExpression(&self) -> Retained<NSExpression>

pub unsafe fn expressionBlock( &self, ) -> NonNull<DynBlock<dyn Fn(*mut AnyObject, NonNull<NSArray<NSExpression>>, *mut NSMutableDictionary) -> NonNull<AnyObject>>>

Available on crate features NSArray and NSDictionary and block2 only.

Safety

• The returned block’s argument 1 must be a valid pointer or null.
• The returned block’s argument 2 must be a valid pointer.
• The returned block’s argument 3 must be a valid pointer or null.

pub unsafe fn expressionValueWithObject_context( &self, object: Option<&AnyObject>, context: Option<&NSMutableDictionary>, ) -> Option<Retained<AnyObject>>

Available on crate feature NSDictionary only.

Safety

• object should be of the correct type.
• context generic should be of the correct type.

pub fn allowEvaluation(&self)

impl NSExpression

Methods declared on superclass NSObject.

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

pub fn new() -> Retained<Self>

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 NSExpression

fn as_ref(&self) -> &AnyObject

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

impl AsRef<NSExpression> for NSExpression

fn as_ref(&self) -> &Self

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

impl AsRef<NSObject> for NSExpression

fn as_ref(&self) -> &NSObject

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

impl Borrow<AnyObject> for NSExpression

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl Borrow<NSObject> for NSExpression

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl ClassType for NSExpression

const NAME: &'static str = "NSExpression"

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

type Super = NSObject

The superclass of this class.

type ThreadKind = <<NSExpression 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 NSExpression

Available on crate feature NSObject only.

type Result = NSExpression

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

impl Debug for NSExpression

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

Formats the value using the given formatter.

impl DefaultRetained for NSExpression

fn default_retained() -> Retained<Self>

The default Retained for a type.

impl Deref for NSExpression

type Target = NSObject

The resulting type after dereferencing.

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

Dereferences the value.

impl Hash for NSExpression

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 NSExpression

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

where Self: Sized,

Increment the reference count of the receiver.

impl NSCoding for NSExpression

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

where Self: Sized + Message,

Available on crate features NSObject and NSCoder only.

Safety

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

where Self: Sized + Message,

Available on crate features NSObject and NSCoder only.

Safety

impl NSCopying for NSExpression

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

where Self: Sized + Message + CopyingHelper,

Available on crate feature NSObject only.

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,

Available on crate feature NSObject only.

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

impl NSObjectProtocol for NSExpression

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 NSSecureCoding for NSExpression

fn supportsSecureCoding() -> bool

where Self: Sized + ClassType,

Available on crate feature NSObject only.

impl PartialEq for NSExpression

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 NSExpression

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

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

impl DowncastTarget for NSExpression

impl Eq for NSExpression