Struct UIDeferredMenuElement

Source

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

Available on crate features UIDeferredMenuElement and UIMenuElement only.

Expand description

Apple’s documentation

Implementations§

Source §

impl UIDeferredMenuElement

Source

pub unsafe fn elementWithProvider( element_provider: &DynBlock<dyn Fn(NonNull<DynBlock<dyn Fn(NonNull<NSArray<UIMenuElement>>)>>)>, mtm: MainThreadMarker, ) -> Retained<Self>

Available on crate feature block2 only.

Returns a placeholder menu element that is replaced with the result of the block’s completion handler. A loading UI takes the place of the element in the menu until it is fulfilled. While the element may be stored and re-used across menus, its block is called only once, when the element is first encountered in a menu.

Parameter elementProvider: Called by the system to request the deferred menu items when the containing menu is presented. Call this block’s completion handler when the menu items are available.

Source

pub unsafe fn elementWithUncachedProvider( element_provider: &DynBlock<dyn Fn(NonNull<DynBlock<dyn Fn(NonNull<NSArray<UIMenuElement>>)>>)>, mtm: MainThreadMarker, ) -> Retained<Self>

Available on crate feature block2 only.

Returns a placeholder menu element that is replaced with the result of the block’s completion handler. A loading UI takes the place of the element in the menu until it is fulfilled. Elements created using this initializer are “uncached”, so their elementProviderblock is called every time the element is displayed.

Parameter elementProvider: Called by the system to request the deferred menu items when the containing menu is presented. Call this block’s completion handler when the menu items are available.

Source §

impl UIDeferredMenuElement

Methods declared on superclass UIMenuElement.

Source

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

Source

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

Source

pub unsafe fn new(mtm: MainThreadMarker) -> Retained<Self>

Methods from Deref<Target = UIMenuElement>§

Source

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

The element’s title.

Source

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

The element’s subtitle.

Source

pub unsafe fn setSubtitle(&self, subtitle: Option<&NSString>)

Setter for subtitle.

Source

pub unsafe fn image(&self) -> Option<Retained<UIImage>>

Available on crate feature UIImage only.

Image to be displayed alongside the element’s title.

Methods from Deref<Target = NSObject>§

Source

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

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>§

Source

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());

Source

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.

Source

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`
    }
}