Struct UIUpdateInfo

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

Available on crate feature UIUpdateInfo only.

Contains detailed information about the current state of the UI update. This information may change as UI update progresses through its phases. Note, that single UI update might service views on different displays simultaneously, in which case such views may have different UIUpdateInfo (e.g. estimatedPresentationTime may differ).

See also Apple’s documentation

Implementations

impl UIUpdateInfo

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

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

pub unsafe fn currentUpdateInfoForWindowScene( window_scene: &UIWindowScene, ) -> Option<Retained<Self>>

Available on crate features UIResponder and UIScene and UIWindowScene only.

pub unsafe fn currentUpdateInfoForView(view: &UIView) -> Option<Retained<Self>>

Available on crate features UIResponder and UIView only.

pub unsafe fn modelTime(&self) -> NSTimeInterval

Reference time that is suitable for driving time based model changes, like animations or physics. Use it as “now” time for the UI update. It’s designed to maintain constant latency between model changes and their on screen presentation. Uses same units as CACurrentMediaTime(). Numerically, this time is close to the start of the UI update, but its exact relation to UI update start time may change depending on frame rate and other UI update parameters.

pub unsafe fn completionDeadlineTime(&self) -> NSTimeInterval

Time by which application has to be done submitting changes to the render server. Missing this completion deadline will result in a presentation delay. Single miss will look like a frame drop, missing repeatedly will look like judder.

pub unsafe fn estimatedPresentationTime(&self) -> NSTimeInterval

Estimated time when UI update changes will become visible on screen. Actual time when pixels change color may differ.

pub unsafe fn isImmediatePresentationExpected(&self) -> bool

YES for UI updates that are expected to present immediately upon completion. Use it to minimize amount of work performed during the UI update. Any processing that is not critical for the frame being presented should be deferred to after UI update is complete. Note, that immediate presentation still might not happen if strict conditions imposed by the system, like committing CATransaction before the completionDeadlineTime, are not satisfied. Similarly, immediate presentation can be denied at various points of the pipeline, if system detects that current CPU or GPU load, power state or frame complexity make reliable immediate presentation impossible or unlikely. Immediate presentation is an extremely challenging mode for the entire system and causes excessive power drain and has high chances of missing intended presentation time, which results in visual judder. Application that use it has high chances of missing intended presentation time, which results in visual judder. Applications that use it should be explicitly designed and tuned to operate in this mode - amount of work in each phase should be precisely controlled. It is primarily reserved for pencil drawing and writing applications where extra low latency makes a noticeable improvement to user experience. Returned value can change during the UI update.

pub unsafe fn isLowLatencyEventDispatchConfirmed(&self) -> bool

YES when it’s guaranteed that low-latency event dispatch will happen during the UI update. When YES is returned, you can rely on low-latency UI update phases to run for this UI update. Use it to avoid doing the same work more than once. For example, when rendering a pencil drawing stroke in after event dispatch and lowLatencyEventDispatchConfirmed is YES, while performingLowLatencyPhases is NO, then it would be better to wait for after low-latency event dispatch to render the stroke. Can change from NO to YES during the UI update, but will never change from YES to NO. When YES is returned, low-latency phases always will be performed. Note, that checking value of this property might cause system to commit to low-latency event dispatch unnecessarily as a side effect - call it only when there’s an intention to act on returned value.

pub unsafe fn isPerformingLowLatencyPhases(&self) -> bool

YES when executing low-latency part of the UI update (specifically between LowLatencyEventDispatch and LowLatencyCATransactionCommit UI update phases). Work in this part of the UI update should be as minimal as possible, especially when immediate presentation is to be attempted. Anything that is not critical to the current UI update must be deferred after LowLatencyCATransactionCommit. Try to avoid using dispatch_after() types of deferral as arbitrary delayed work will potentially interfere with following UI updates.

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 UIUpdateInfo

fn as_ref(&self) -> &AnyObject

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

impl AsRef<NSObject> for UIUpdateInfo

fn as_ref(&self) -> &NSObject

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

impl AsRef<UIUpdateInfo> for UIUpdateInfo

fn as_ref(&self) -> &Self

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

impl Borrow<AnyObject> for UIUpdateInfo

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl Borrow<NSObject> for UIUpdateInfo

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl ClassType for UIUpdateInfo

const NAME: &'static str = "UIUpdateInfo"

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 UIUpdateInfo

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

Formats the value using the given formatter.

impl Deref for UIUpdateInfo

type Target = NSObject

The resulting type after dereferencing.

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

Dereferences the value.

impl Hash for UIUpdateInfo

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 UIUpdateInfo

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

where Self: Sized,

Increment the reference count of the receiver.

impl NSObjectProtocol for UIUpdateInfo

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 UIUpdateInfo

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 UIUpdateInfo

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

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

impl DowncastTarget for UIUpdateInfo

impl Eq for UIUpdateInfo