RACScheduler Class Reference

Inherits from	NSObject
Declared in	RACScheduler.h RACScheduler.m

Overview

Schedulers are used to control when and where work is performed. A private interface for internal RAC use only.

Tasks

Other Methods

+ immediateScheduler
+ mainThreadScheduler
+ schedulerWithPriority:name:
+ schedulerWithPriority:
+ scheduler
+ currentScheduler
– schedule:
– after:schedule:
– afterDelay:schedule:
– after:repeatingEvery:withLeeway:schedule:
– scheduleRecursiveBlock:

Class Methods

currentScheduler

The current scheduler. This will only be valid when used from within a [RACScheduler schedule:] block or when on the main thread.

+ (RACScheduler *)currentScheduler

Declared In

RACScheduler.h

immediateScheduler

A singleton scheduler that immediately executes the blocks it is given.

+ (RACScheduler *)immediateScheduler

Discussion

Note: Unlike most other schedulers, this does not set the current scheduler. There may still be a valid currentScheduler if this is used within a block scheduled on a different scheduler.

Declared In

RACScheduler.h

mainThreadScheduler

A singleton scheduler that executes blocks in the main thread.

+ (RACScheduler *)mainThreadScheduler

Declared In

RACScheduler.h

scheduler

Invokes schedulerWithPriority: with RACSchedulerPriorityDefault.

+ (RACScheduler *)scheduler

Declared In

RACScheduler.h

schedulerWithPriority:

Invokes schedulerWithPriority:name: with a default name.

+ (RACScheduler *)schedulerWithPriority:(RACSchedulerPriority)priority

Declared In

RACScheduler.h

schedulerWithPriority:name:

Creates and returns a new background scheduler with the given priority and name. The name is for debug and instrumentation purposes only.

+ (RACScheduler *)schedulerWithPriority:(RACSchedulerPriority)priority name:(NSString *)name

Discussion

Scheduler creation is cheap. It’s unnecessary to save the result of this method call unless you want to serialize some actions on the same background scheduler.

Declared In

RACScheduler.h

subscriptionScheduler

A dedicated scheduler that fills two requirements:

+ (instancetype)subscriptionScheduler

Discussion

. By the time subscription happens, we need a valid currentScheduler.
. Subscription should happen as soon as possible.

To fulfill those two, if we already have a valid currentScheduler, it immediately executes scheduled blocks. If we don’t, it will execute scheduled blocks with a private background scheduler.

Declared In

RACScheduler+Private.h

Instance Methods

after:repeatingEvery:withLeeway:schedule:

Reschedule the given block at a particular interval, starting at a specific time, and with a given leeway for deferral.

- (RACDisposable *)after:(NSDate *)date repeatingEvery:(NSTimeInterval)interval withLeeway:(NSTimeInterval)leeway schedule:(void ( ^ ) ( void ))block

Discussion

Note that blocks scheduled for a certain time will not preempt any other scheduled work that is executing at the time.

Regardless of the value of leeway, the given block may not execute exactly at when or exactly on successive intervals, whether due to system load or because another block is currently being run on the scheduler.

It is considered undefined behavior to invoke this method on the immediateScheduler.

date - The earliest time at which block should begin executing. The block may not execute immediately at this time, whether due to system load or another block on the scheduler currently being run. Cannot be nil. interval - The interval at which the block should be rescheduled, starting from date. This will use the system wall clock, to avoid skew when the computer goes to sleep. leeway - A hint to the system indicating the number of seconds that each scheduling can be deferred. Note that this is just a hint, and there may be some additional latency no matter what. block - The block to repeatedly schedule for execution. Cannot be nil.

Returns a disposable which can be used to cancel the automatic scheduling and rescheduling, or nil if cancellation is not supported.

Declared In

RACScheduler.h

after:schedule:

Schedule the given block for execution on the scheduler at or after a specific time.

- (RACDisposable *)after:(NSDate *)date schedule:(void ( ^ ) ( void ))block

Discussion

Note that blocks scheduled for a certain time will not preempt any other scheduled work that is executing at the time.

When invoked on the immediateScheduler, the calling thread will block until the specified time.

Returns a disposable which can be used to cancel the scheduled block before it begins executing, or nil if cancellation is not supported.

Declared In

RACScheduler.h

afterDelay:schedule:

Schedule the given block for execution on the scheduler after the delay.

- (RACDisposable *)afterDelay:(NSTimeInterval)delay schedule:(void ( ^ ) ( void ))block

Discussion

Converts the delay into an NSDate, then invokes after:schedule:.

Declared In

RACScheduler.h

initWithName:

Initializes the receiver with the given name.

- (id)initWithName:(NSString *)name

Discussion

name - The name of the scheduler. If nil, a default name will be used.

Returns the initialized object.

Declared In

RACScheduler+Private.h

schedule:

Schedule the given block for execution on the scheduler.

- (RACDisposable *)schedule:(void ( ^ ) ( void ))block

Discussion

Scheduled blocks will be executed in the order in which they were scheduled.

block - The block to schedule for execution. Cannot be nil.

Returns a disposable which can be used to cancel the scheduled block before it begins executing, or nil if cancellation is not supported.

Declared In

RACScheduler.h

scheduleRecursiveBlock:

Schedule the given recursive block for execution on the scheduler. The scheduler will automatically flatten any recursive scheduling into iteration instead, so this can be used without issue for blocks that may keep invoking themselves forever.

- (RACDisposable *)scheduleRecursiveBlock:(RACSchedulerRecursiveBlock)recursiveBlock

Discussion

Scheduled blocks will be executed in the order in which they were scheduled.

recursiveBlock - The block to schedule for execution. When invoked, the recursive block will be passed a void (^)(void) block which will reschedule the recursive block at the end of the receiver’s queue. This passed-in block will automatically skip scheduling if the scheduling of the recursiveBlock was disposed in the meantime.

Returns a disposable which can be used to cancel the scheduled block before it begins executing, or to stop it from rescheduling if it’s already begun execution.

Declared In

RACScheduler.h