Struct UIUpdateLink 

pub struct UIUpdateLink { /* private fields */ }

Available on crate feature UIUpdateLink only.

Allows to formally participate in UI updates and influence UI update behavior.

See also Apple’s documentation

Implementations

impl UIUpdateLink

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

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

pub fn updateLinkForWindowScene( window_scene: &UIWindowScene, ) -> Retained<UIUpdateLink>

Available on crate features UIResponder and UIScene and UIWindowScene only.

pub fn updateLinkForView(view: &UIView) -> Retained<UIUpdateLink>

Available on crate features UIResponder and UIView only.

pub fn addActionToPhase_handler( &self, phase: &UIUpdateActionPhase, handler: &DynBlock<dyn Fn(NonNull<UIUpdateLink>, NonNull<UIUpdateInfo>)>, )

Available on crate features UIUpdateActionPhase and UIUpdateInfo and block2 only.

pub unsafe fn addActionToPhase_target_selector( &self, phase: &UIUpdateActionPhase, target: &AnyObject, selector: Sel, )

Available on crate feature UIUpdateActionPhase only.

Safety

• target should be of the correct type.
• selector must be a valid selector.

pub fn isEnabled(&self) -> bool

It’s required to enable the Update Link for it to have effect and for its actions to be invoked.

pub fn setEnabled(&self, enabled: bool)

Setter for isEnabled.

pub fn requiresContinuousUpdates(&self) -> bool

By default, UIUpdateLink is a passive UI update observer. Its actions will only be called when UI update is being produced. When this property is set to YES, UIUpdateLink will request continuous UI updates by itself.

pub fn setRequiresContinuousUpdates(&self, requires_continuous_updates: bool)

Setter for requiresContinuousUpdates.

pub fn wantsLowLatencyEventDispatch(&self) -> bool

Request dispatch of low-latency eligible events in LowLatencyEventDispatch phase. Low latency eligible events are dispatch in the middle of the UI update, meaning that to handle them application has half the time, compared to events dispatched normally. Consult -[UIUpdateInfo completionDeadlineTime] for exact completion deadline time.

pub fn setWantsLowLatencyEventDispatch( &self, wants_low_latency_event_dispatch: bool, )

Setter for wantsLowLatencyEventDispatch.

pub fn wantsImmediatePresentation(&self) -> bool

Request immediate frame presentation. When enabled, system will request immediate rendering of the display frame after last CATransaction commit for the current UI update. This allows to reduce input to display latency, as rendered display frame will be presented one frame duration sooner. However, for this to happen amount of work submitted to render server should be minimal, otherwise it will not be able to submit frame for presentation in time. This capability is primarily useful for pencil drawing applications where low input to display latency is critical for good user experience. Applications that request immediate presentation must be profiled thoroughly to ensure that amount of application and render server work is adequate. When application requests immediate presentation, but fails to keep work complexity at minimum, user will experience on screen judder, as frames will not be presented at their intended time.

pub fn setWantsImmediatePresentation(&self, wants_immediate_presentation: bool)

Setter for wantsImmediatePresentation.

pub fn preferredFrameRateRange(&self) -> CAFrameRateRange

Available on crate feature objc2-quartz-core and non-watchOS only.

Preferred frame rate range. Even when not forcing periodic updates, this will still express intention to the system. Use CAFrameRateRangeDefault (default value) to not request any specific frame rate range.

pub fn setPreferredFrameRateRange( &self, preferred_frame_rate_range: CAFrameRateRange, )

Available on crate feature objc2-quartz-core and non-watchOS only.

Setter for preferredFrameRateRange.

pub fn currentUpdateInfo(&self) -> Option<Retained<UIUpdateInfo>>

Available on crate feature UIUpdateInfo only.

During UI update, returns UIUpdateInfo instance describing current UI update state. Returns nil outside of UI update.

impl UIUpdateLink

Convenience.

pub fn addActionWithHandler( &self, handler: &DynBlock<dyn Fn(NonNull<UIUpdateLink>, NonNull<UIUpdateInfo>)>, )

Available on crate features UIUpdateInfo and block2 only.

Adds action to UIUpdateActionPhase.beforeCADisplayLinkDispatch phase.

pub unsafe fn addActionWithTarget_selector( &self, target: &AnyObject, selector: Sel, )

Adds action to UIUpdateActionPhase.beforeCADisplayLinkDispatch phase.

Safety

• target should be of the correct type.
• selector must be a valid selector.

pub fn updateLinkForWindowScene_actionHandler( window_scene: &UIWindowScene, handler: &DynBlock<dyn Fn(NonNull<UIUpdateLink>, NonNull<UIUpdateInfo>)>, ) -> Retained<UIUpdateLink>

Available on crate features UIResponder and UIScene and UIUpdateInfo and UIWindowScene and block2 only.

Adds action to UIUpdateActionPhase.beforeCADisplayLinkDispatch phase.

pub unsafe fn updateLinkForWindowScene_actionTarget_selector( window_scene: &UIWindowScene, target: &AnyObject, selector: Sel, ) -> Retained<UIUpdateLink>

Available on crate features UIResponder and UIScene and UIWindowScene only.

Adds action to UIUpdateActionPhase.beforeCADisplayLinkDispatch phase.

Safety

• target should be of the correct type.
• selector must be a valid selector.

pub fn updateLinkForView_actionHandler( view: &UIView, handler: &DynBlock<dyn Fn(NonNull<UIUpdateLink>, NonNull<UIUpdateInfo>)>, ) -> Retained<UIUpdateLink>

Available on crate features UIResponder and UIUpdateInfo and UIView and block2 only.

Adds action to UIUpdateActionPhase.beforeCADisplayLinkDispatch phase.

pub unsafe fn updateLinkForView_actionTarget_selector( view: &UIView, target: &AnyObject, selector: Sel, ) -> Retained<UIUpdateLink>

Available on crate features UIResponder and UIView only.

Adds action to UIUpdateActionPhase.beforeCADisplayLinkDispatch phase.

Safety

• target should be of the correct type.
• selector must be a valid selector.

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 AsRef<AnyObject> for UIUpdateLink

fn as_ref(&self) -> &AnyObject

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

impl AsRef<NSObject> for UIUpdateLink

fn as_ref(&self) -> &NSObject

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

impl AsRef<UIUpdateLink> for UIUpdateLink

fn as_ref(&self) -> &Self

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

impl Borrow<AnyObject> for UIUpdateLink

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl Borrow<NSObject> for UIUpdateLink

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl ClassType for UIUpdateLink

const NAME: &'static str = "UIUpdateLink"

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 Debug for UIUpdateLink

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

Formats the value using the given formatter.

impl Deref for UIUpdateLink

type Target = NSObject

The resulting type after dereferencing.

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

Dereferences the value.

impl Hash for UIUpdateLink

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 UIUpdateLink

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

where Self: Sized,

Increment the reference count of the receiver.

impl NSObjectProtocol for UIUpdateLink

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 UIUpdateLink

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 UIUpdateLink

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

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

impl DowncastTarget for UIUpdateLink

impl Eq for UIUpdateLink