Struct BGTaskScheduler 

pub struct BGTaskScheduler { /* private fields */ }

Available on crate feature BGTaskScheduler only.

A class for scheduling task requests that launch your app in the background.

Background tasks give your app a way to run code while the app is suspended. To learn how to register, schedule, and run a background task, see <doc ://com.apple.documentation/documentation/uikit/app_and_environment/scenes/preparing_your_ui_to_run_in_the_background/using_background_tasks_to_update_your_app>.

See also Apple’s documentation

Implementations

impl BGTaskScheduler

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

pub unsafe fn new() -> Retained<Self>

pub unsafe fn sharedScheduler() -> Retained<BGTaskScheduler>

The shared background task scheduler instance.

pub unsafe fn supportedResources() -> BGContinuedProcessingTaskRequestResources

Available on crate feature BGTaskRequest only.

A bitfield of the resources the device supports for BackgroundTasks/BGContinuedProcessingTaskRequest instances.

pub unsafe fn registerForTaskWithIdentifier_usingQueue_launchHandler( &self, identifier: &NSString, queue: Option<&DispatchQueue>, launch_handler: &DynBlock<dyn Fn(NonNull<BGTask>)>, ) -> bool

Available on crate features BGTask and block2 and dispatch2 only.

Register a launch handler for the task with the associated identifier that’s executed on the specified queue.

Every identifier in the <doc ://com.apple.documentation/documentation/bundleresources/information_property_list/bgtaskschedulerpermittedidentifiers> requires a handler. Registration of all launch handlers must be complete before the end of <doc ://com.apple.documentation/documentation/uikit/uiapplicationdelegate/1623053-applicationdidfinishlaunching>.

You must register launch handlers before your application finishes launching (BGContinuedProcessingTask registrations are exempt from this requirement). Attempting to register a handler after launch or multiple handlers for the same identifier is an error. Although you may submit task requests from some extensions, only the host app will be launched to handle background work.

• Parameters:
• identifier: The identifier for the task that will be handled by the provided launch handler.
• queue: A queue for executing the task. Pass nil to use a default background queue.
• launchHandler: The system runs the block of code for the launch handler when it launches the app in the background. The block takes a single parameter, a BGTask object used for assigning an expiration handler and for setting a completion status. The block has no return value. Assign an expiration handler to the task’s expirationHandler property and call setTaskCompletedWithSuccess: when the background work is complete.
• Returns: Returns <doc ://com.apple.documentation/documentation/objectivec/yes> if the launch handler was registered. Returns <doc ://com.apple.documentation/documentation/objectivec/no> if the identifier isn’t included in the <doc ://com.apple.documentation/documentation/bundleresources/information_property_list/bgtaskschedulerpermittedidentifiers> Info.plist.
• Important: Register each task identifier only once. The system kills the app on the second registration of the same task identifier.

Safety

queue possibly has additional threading requirements.

pub unsafe fn submitTaskRequest_error( &self, task_request: &BGTaskRequest, ) -> Result<(), Retained<NSError>>

Available on crate feature BGTaskRequest only.

Submit a previously registered background task for execution.

Submitting a task request for an unexecuted task that’s already in the queue replaces the previous task request.

There can be a total of 1 refresh task and 10 processing tasks scheduled at any time. Trying to schedule more tasks returns BGTaskSchedulerErrorCode/BGTaskSchedulerErrorCodeTooManyPendingTaskRequests.

• Parameters:
• taskRequest: The task request object representing the parameters of the background task to be scheduled.
• error: If an error occurs, upon return contains an error object that indicates why the request was rejected
• Returns: YES if the request was successfully submitted; NO if there was an error

pub unsafe fn cancelTaskRequestWithIdentifier(&self, identifier: &NSString)

Cancel a previously scheduled task request.

• Parameters:
• identifier: The identifier of the previously submitted task request to cancel.

pub unsafe fn cancelAllTaskRequests(&self)

Cancel all previously submitted task requests.

pub unsafe fn getPendingTaskRequestsWithCompletionHandler( &self, completion_handler: &DynBlock<dyn Fn(NonNull<NSArray<BGTaskRequest>>)>, )

Available on crate features BGTaskRequest and block2 only.

Returns a list of all task requests that have been submitted but not yet completed.

The handler takes a single parameter tasksRequests, an array of BGTaskRequest objects. The array is empty if there are no scheduled tasks.

The objects passed in the array are copies of the existing requests. Changing the attributes of a request has no effect. To change the attributes submit a new task request using BGTaskScheduler/submitTaskRequest:error:.

• Parameters:
• completionHandler: The completion handler called with the pending tasks.
• Note: The handler may execute on a background thread.

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 BGTaskScheduler

fn as_ref(&self) -> &AnyObject

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

impl AsRef<BGTaskScheduler> for BGTaskScheduler

fn as_ref(&self) -> &Self

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

impl AsRef<NSObject> for BGTaskScheduler

fn as_ref(&self) -> &NSObject

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

impl Borrow<AnyObject> for BGTaskScheduler

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl Borrow<NSObject> for BGTaskScheduler

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl ClassType for BGTaskScheduler

const NAME: &'static str = "BGTaskScheduler"

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

type Super = NSObject

The superclass of this class.

type ThreadKind = <<BGTaskScheduler 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 Debug for BGTaskScheduler

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

Formats the value using the given formatter.

impl Deref for BGTaskScheduler

type Target = NSObject

The resulting type after dereferencing.

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

Dereferences the value.

impl Hash for BGTaskScheduler

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 BGTaskScheduler

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

where Self: Sized,

Increment the reference count of the receiver.

impl NSObjectProtocol for BGTaskScheduler

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 BGTaskScheduler

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 BGTaskScheduler

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

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

impl DowncastTarget for BGTaskScheduler

impl Eq for BGTaskScheduler