Struct UICollectionViewDiffableDataSourceSectionSnapshotHandlers 

pub struct UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType: ?Sized = AnyObject> { /* private fields */ }

Available on crate feature UIDiffableDataSource only.

Apple’s documentation

Implementations

impl<ItemType: ?Sized + Message> UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

pub unsafe fn cast_unchecked<NewItemType: ?Sized + Message>( &self, ) -> &UICollectionViewDiffableDataSourceSectionSnapshotHandlers<NewItemType>

Unchecked conversion of the generic parameter.

Safety

The generic must be valid to reinterpret as the given type.

impl<ItemType: Message> UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

pub unsafe fn shouldExpandItemHandler( &self, ) -> *mut DynBlock<dyn Fn(NonNull<ItemType>) -> Bool>

Available on crate feature block2 only.

Safety

The returned block’s argument must be a valid pointer.

pub fn setShouldExpandItemHandler( &self, should_expand_item_handler: Option<&DynBlock<dyn Fn(NonNull<ItemType>) -> Bool>>, )

Available on crate feature block2 only.

Setter for shouldExpandItemHandler.

This is copied when set.

pub unsafe fn willExpandItemHandler( &self, ) -> *mut DynBlock<dyn Fn(NonNull<ItemType>)>

Available on crate feature block2 only.

Safety

The returned block’s argument must be a valid pointer.

pub fn setWillExpandItemHandler( &self, will_expand_item_handler: Option<&DynBlock<dyn Fn(NonNull<ItemType>)>>, )

Available on crate feature block2 only.

Setter for willExpandItemHandler.

This is copied when set.

pub unsafe fn shouldCollapseItemHandler( &self, ) -> *mut DynBlock<dyn Fn(NonNull<ItemType>) -> Bool>

Available on crate feature block2 only.

Safety

The returned block’s argument must be a valid pointer.

pub fn setShouldCollapseItemHandler( &self, should_collapse_item_handler: Option<&DynBlock<dyn Fn(NonNull<ItemType>) -> Bool>>, )

Available on crate feature block2 only.

Setter for shouldCollapseItemHandler.

This is copied when set.

pub unsafe fn willCollapseItemHandler( &self, ) -> *mut DynBlock<dyn Fn(NonNull<ItemType>)>

Available on crate feature block2 only.

Safety

The returned block’s argument must be a valid pointer.

pub fn setWillCollapseItemHandler( &self, will_collapse_item_handler: Option<&DynBlock<dyn Fn(NonNull<ItemType>)>>, )

Available on crate feature block2 only.

Setter for willCollapseItemHandler.

This is copied when set.

pub unsafe fn snapshotForExpandingParentItemHandler( &self, ) -> *mut DynBlock<dyn Fn(NonNull<ItemType>, NonNull<NSDiffableDataSourceSectionSnapshot<ItemType>>) -> NonNull<NSDiffableDataSourceSectionSnapshot<ItemType>>>

Available on crate features NSDiffableDataSourceSectionSnapshot and block2 only.

Safety

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

pub unsafe fn setSnapshotForExpandingParentItemHandler( &self, snapshot_for_expanding_parent_item_handler: Option<&DynBlock<dyn Fn(NonNull<ItemType>, NonNull<NSDiffableDataSourceSectionSnapshot<ItemType>>) -> NonNull<NSDiffableDataSourceSectionSnapshot<ItemType>>>>, )

Available on crate features NSDiffableDataSourceSectionSnapshot and block2 only.

Setter for snapshotForExpandingParentItemHandler.

This is copied when set.

Safety

snapshot_for_expanding_parent_item_handler block’s return must be a valid pointer.

impl<ItemType: Message> UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

Methods declared on superclass NSObject.

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

pub fn new(mtm: MainThreadMarker) -> 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

Available on crate feature UIIndirectScribbleInteraction only.

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.

Available on crate feature UIIndirectScribbleInteraction only.

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,

Available on crate feature UIIndirectScribbleInteraction only.

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<ItemType: ?Sized + Message> AsRef<AnyObject> for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

fn as_ref(&self) -> &AnyObject

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

impl<ItemType: ?Sized + Message> AsRef<NSObject> for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

fn as_ref(&self) -> &NSObject

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

impl<ItemType: ?Sized + Message> AsRef<UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>> for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

fn as_ref(&self) -> &Self

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

impl<ItemType: ?Sized + Message> Borrow<AnyObject> for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl<ItemType: ?Sized + Message> Borrow<NSObject> for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl<ItemType: ?Sized + Message> ClassType for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

const NAME: &'static str = "UICollectionViewDiffableDataSourceSectionSnapshotHandlers"

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

type Super = NSObject

The superclass of this class.

type ThreadKind = dyn MainThreadOnly

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<ItemType: ?Sized + Message> CopyingHelper for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

type Result = UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

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

impl<ItemType: ?Sized> Debug for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

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

Formats the value using the given formatter.

impl<ItemType: ?Sized + Message> Deref for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

type Target = NSObject

The resulting type after dereferencing.

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

Dereferences the value.

impl<ItemType: ?Sized> Hash for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

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<ItemType: ?Sized + Message> Message for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

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

where Self: Sized,

Increment the reference count of the receiver.

impl<ItemType: ?Sized> NSCopying for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

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<ItemType: ?Sized> NSObjectProtocol for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

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<ItemType: ?Sized> PartialEq for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

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<ItemType: ?Sized + Message> RefEncode for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>

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

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

impl DowncastTarget for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<AnyObject>

impl<ItemType: ?Sized> Eq for UICollectionViewDiffableDataSourceSectionSnapshotHandlers<ItemType>