pub struct CKFetchRecordZoneChangesOperation { /* private fields */ }CKDatabaseOperation and CKFetchRecordZoneChangesOperation and CKOperation only.Expand description
This operation will fetch records changes across the given record zones
For each
previousServerChangeTokenpassed in with a
CKFetchRecordZoneChangesConfiguration,only records that have changed since that anchor will be fetched.
If this is your first fetch of a zone or if you wish to re-fetch all records within a zone, do not include a
previousServerChangeToken.Change tokens are opaque tokens and clients should not infer any behavior based on their content.
See also Apple’s documentation
Implementations§
Source§impl CKFetchRecordZoneChangesOperation
impl CKFetchRecordZoneChangesOperation
pub unsafe fn init(this: Allocated<Self>) -> Retained<Self>
pub unsafe fn initWithRecordZoneIDs_configurationsByRecordZoneID( this: Allocated<Self>, record_zone_i_ds: &NSArray<CKRecordZoneID>, configurations_by_record_zone_id: Option<&NSDictionary<CKRecordZoneID, CKFetchRecordZoneChangesConfiguration>>, ) -> Retained<Self>
CKRecordZoneID only.Sourcepub unsafe fn recordZoneIDs(&self) -> Option<Retained<NSArray<CKRecordZoneID>>>
Available on crate feature CKRecordZoneID only.
pub unsafe fn recordZoneIDs(&self) -> Option<Retained<NSArray<CKRecordZoneID>>>
CKRecordZoneID only.Sourcepub unsafe fn setRecordZoneIDs(
&self,
record_zone_i_ds: Option<&NSArray<CKRecordZoneID>>,
)
Available on crate feature CKRecordZoneID only.
pub unsafe fn setRecordZoneIDs( &self, record_zone_i_ds: Option<&NSArray<CKRecordZoneID>>, )
CKRecordZoneID only.Sourcepub unsafe fn configurationsByRecordZoneID(
&self,
) -> Option<Retained<NSDictionary<CKRecordZoneID, CKFetchRecordZoneChangesConfiguration>>>
Available on crate feature CKRecordZoneID only.
pub unsafe fn configurationsByRecordZoneID( &self, ) -> Option<Retained<NSDictionary<CKRecordZoneID, CKFetchRecordZoneChangesConfiguration>>>
CKRecordZoneID only.Sourcepub unsafe fn setConfigurationsByRecordZoneID(
&self,
configurations_by_record_zone_id: Option<&NSDictionary<CKRecordZoneID, CKFetchRecordZoneChangesConfiguration>>,
)
Available on crate feature CKRecordZoneID only.
pub unsafe fn setConfigurationsByRecordZoneID( &self, configurations_by_record_zone_id: Option<&NSDictionary<CKRecordZoneID, CKFetchRecordZoneChangesConfiguration>>, )
CKRecordZoneID only.Setter for configurationsByRecordZoneID.
This is copied when set.
§Safety
This might not be thread-safe.
Sourcepub unsafe fn fetchAllChanges(&self) -> bool
pub unsafe fn fetchAllChanges(&self) -> bool
Determines if the operation should fetch all changes from the server before completing.
When set to YES, this operation will send repeated requests to the server until all record changes have been fetched.
recordZoneChangeTokensUpdatedBlockwill be invoked periodically, to give clients an updated change token so that already-fetched record changes don’t need to be re-fetched on a subsequent operation.
recordZoneFetchCompletionBlockwill only be called once and
moreComingwill always be NO.
When set to NO, it is the responsibility of the caller to issue subsequent fetch-changes operations when
moreComingis YES in a
recordZoneFetchCompletionBlockinvocation.
fetchAllChangesis YES by default
This property is not atomic.
§Safety
This might not be thread-safe.
Sourcepub unsafe fn setFetchAllChanges(&self, fetch_all_changes: bool)
pub unsafe fn setFetchAllChanges(&self, fetch_all_changes: bool)
Sourcepub unsafe fn recordChangedBlock(
&self,
) -> *mut DynBlock<dyn Fn(NonNull<CKRecord>)>
👎Deprecated: Use recordWasChangedBlock instead, which surfaces per-record errorsAvailable on crate features CKRecord and block2 only.
pub unsafe fn recordChangedBlock( &self, ) -> *mut DynBlock<dyn Fn(NonNull<CKRecord>)>
CKRecord and block2 only.If the replacement callback
recordWasChangedBlockis set, this callback block is ignored.
Each
CKOperationinstance has a private serial queue. This queue is used for all callback block invocations.
This block may share mutable state with other blocks assigned to this operation, but any such mutable state
should not be concurrently used outside of blocks assigned to this operation.
This property is not atomic.
§Safety
- The returned block’s argument must be a valid pointer.
- This might not be thread-safe.
Sourcepub unsafe fn setRecordChangedBlock(
&self,
record_changed_block: Option<&DynBlock<dyn Fn(NonNull<CKRecord>)>>,
)
👎Deprecated: Use recordWasChangedBlock instead, which surfaces per-record errorsAvailable on crate features CKRecord and block2 only.
pub unsafe fn setRecordChangedBlock( &self, record_changed_block: Option<&DynBlock<dyn Fn(NonNull<CKRecord>)>>, )
CKRecord and block2 only.Sourcepub unsafe fn recordWasChangedBlock(
&self,
) -> *mut DynBlock<dyn Fn(NonNull<CKRecordID>, *mut CKRecord, *mut NSError)>
Available on crate features CKRecord and CKRecordID and block2 only.
pub unsafe fn recordWasChangedBlock( &self, ) -> *mut DynBlock<dyn Fn(NonNull<CKRecordID>, *mut CKRecord, *mut NSError)>
CKRecord and CKRecordID and block2 only.If a record fails in post-processing (say, a network failure materializing a
CKAssetrecord field), the per-record error will be passed here.
Each
CKOperationinstance has a private serial queue. This queue is used for all callback block invocations.
This block may share mutable state with other blocks assigned to this operation, but any such mutable state
should not be concurrently used outside of blocks assigned to this operation.
This property is not atomic.
§Safety
- The returned block’s argument 1 must be a valid pointer.
- The returned block’s argument 2 must be a valid pointer or null.
- The returned block’s argument 3 must be a valid pointer or null.
- This might not be thread-safe.
Sourcepub unsafe fn setRecordWasChangedBlock(
&self,
record_was_changed_block: Option<&DynBlock<dyn Fn(NonNull<CKRecordID>, *mut CKRecord, *mut NSError)>>,
)
Available on crate features CKRecord and CKRecordID and block2 only.
pub unsafe fn setRecordWasChangedBlock( &self, record_was_changed_block: Option<&DynBlock<dyn Fn(NonNull<CKRecordID>, *mut CKRecord, *mut NSError)>>, )
CKRecord and CKRecordID and block2 only.Sourcepub unsafe fn recordWithIDWasDeletedBlock(
&self,
) -> *mut DynBlock<dyn Fn(NonNull<CKRecordID>, NonNull<CKRecordType>)>
Available on crate features CKRecord and CKRecordID and block2 only.
pub unsafe fn recordWithIDWasDeletedBlock( &self, ) -> *mut DynBlock<dyn Fn(NonNull<CKRecordID>, NonNull<CKRecordType>)>
CKRecord and CKRecordID and block2 only.Each
CKOperationinstance has a private serial queue. This queue is used for all callback block invocations.
This block may share mutable state with other blocks assigned to this operation, but any such mutable state
should not be concurrently used outside of blocks assigned to this operation.
This property is not atomic.
§Safety
- The returned block’s argument 1 must be a valid pointer.
- The returned block’s argument 2 must be a valid pointer.
- This might not be thread-safe.
Sourcepub unsafe fn setRecordWithIDWasDeletedBlock(
&self,
record_with_id_was_deleted_block: Option<&DynBlock<dyn Fn(NonNull<CKRecordID>, NonNull<CKRecordType>)>>,
)
Available on crate features CKRecord and CKRecordID and block2 only.
pub unsafe fn setRecordWithIDWasDeletedBlock( &self, record_with_id_was_deleted_block: Option<&DynBlock<dyn Fn(NonNull<CKRecordID>, NonNull<CKRecordType>)>>, )
CKRecord and CKRecordID and block2 only.Setter for recordWithIDWasDeletedBlock.
This is copied when set.
§Safety
This might not be thread-safe.
Sourcepub unsafe fn recordZoneChangeTokensUpdatedBlock(
&self,
) -> *mut DynBlock<dyn Fn(NonNull<CKRecordZoneID>, *mut CKServerChangeToken, *mut NSData)>
Available on crate features CKRecordZoneID and CKServerChangeToken and block2 only.
pub unsafe fn recordZoneChangeTokensUpdatedBlock( &self, ) -> *mut DynBlock<dyn Fn(NonNull<CKRecordZoneID>, *mut CKServerChangeToken, *mut NSData)>
CKRecordZoneID and CKServerChangeToken and block2 only.Clients are responsible for saving this per-recordZone
serverChangeTokenand passing it in to the next call to
CKFetchRecordZoneChangesOperation.Note that a fetch can fail partway. If that happens, an updated change token may be returned in this block so that already fetched records don’t need to be re-downloaded on a subsequent operation.
recordZoneChangeTokensUpdatedBlockwill not be called after the last batch of changes in a zone; the
recordZoneFetchCompletionBlockblock will be called instead.
The
clientChangeTokenDatafrom the most recent
CKModifyRecordsOperationissued on this zone is also returned, or nil if none was provided.
If the server returns a
CKErrorChangeTokenExpirederror, the
serverChangeTokenused for this record zone when initting this operation was too old and the client should toss its local cache and re-fetch the changes in this record zone starting with a nil
serverChangeToken.``recordZoneChangeTokensUpdatedBlockwill not be called if
fetchAllChangesis NO.
Each
CKOperationinstance has a private serial queue. This queue is used for all callback block invocations.
This block may share mutable state with other blocks assigned to this operation, but any such mutable state
should not be concurrently used outside of blocks assigned to this operation.
This property is not atomic.
§Safety
- The returned block’s argument 1 must be a valid pointer.
- The returned block’s argument 2 must be a valid pointer or null.
- The returned block’s argument 3 must be a valid pointer or null.
- This might not be thread-safe.
Sourcepub unsafe fn setRecordZoneChangeTokensUpdatedBlock(
&self,
record_zone_change_tokens_updated_block: Option<&DynBlock<dyn Fn(NonNull<CKRecordZoneID>, *mut CKServerChangeToken, *mut NSData)>>,
)
Available on crate features CKRecordZoneID and CKServerChangeToken and block2 only.
pub unsafe fn setRecordZoneChangeTokensUpdatedBlock( &self, record_zone_change_tokens_updated_block: Option<&DynBlock<dyn Fn(NonNull<CKRecordZoneID>, *mut CKServerChangeToken, *mut NSData)>>, )
CKRecordZoneID and CKServerChangeToken and block2 only.Setter for recordZoneChangeTokensUpdatedBlock.
This is copied when set.
§Safety
This might not be thread-safe.
Sourcepub unsafe fn recordZoneFetchCompletionBlock(
&self,
) -> *mut DynBlock<dyn Fn(NonNull<CKRecordZoneID>, *mut CKServerChangeToken, *mut NSData, Bool, *mut NSError)>
Available on crate features CKRecordZoneID and CKServerChangeToken and block2 only.
pub unsafe fn recordZoneFetchCompletionBlock( &self, ) -> *mut DynBlock<dyn Fn(NonNull<CKRecordZoneID>, *mut CKServerChangeToken, *mut NSData, Bool, *mut NSError)>
CKRecordZoneID and CKServerChangeToken and block2 only.This property is not atomic.
§Safety
- The returned block’s argument 1 must be a valid pointer.
- The returned block’s argument 2 must be a valid pointer or null.
- The returned block’s argument 3 must be a valid pointer or null.
- The returned block’s argument 5 must be a valid pointer or null.
- This might not be thread-safe.
Sourcepub unsafe fn setRecordZoneFetchCompletionBlock(
&self,
record_zone_fetch_completion_block: Option<&DynBlock<dyn Fn(NonNull<CKRecordZoneID>, *mut CKServerChangeToken, *mut NSData, Bool, *mut NSError)>>,
)
Available on crate features CKRecordZoneID and CKServerChangeToken and block2 only.
pub unsafe fn setRecordZoneFetchCompletionBlock( &self, record_zone_fetch_completion_block: Option<&DynBlock<dyn Fn(NonNull<CKRecordZoneID>, *mut CKServerChangeToken, *mut NSData, Bool, *mut NSError)>>, )
CKRecordZoneID and CKServerChangeToken and block2 only.Setter for recordZoneFetchCompletionBlock.
This is copied when set.
§Safety
This might not be thread-safe.
Sourcepub unsafe fn fetchRecordZoneChangesCompletionBlock(
&self,
) -> *mut DynBlock<dyn Fn(*mut NSError)>
Available on crate feature block2 only.
pub unsafe fn fetchRecordZoneChangesCompletionBlock( &self, ) -> *mut DynBlock<dyn Fn(*mut NSError)>
block2 only.This block is called when the operation completes.
serverChangeToken-spreviously returned via a
recordZoneChangeTokensUpdatedBlockor
recordZoneFetchCompletionBlockinvocation, along with the record changes that preceded it, are valid even if there is a subsequent
operationErrorIf the error is
CKErrorPartialFailure,the error’s userInfo dictionary contains a dictionary of recordIDs and zoneIDs to errors keyed off of
CKPartialErrorsByItemIDKey.Each
CKOperationinstance has a private serial queue. This queue is used for all callback block invocations.
This block may share mutable state with other blocks assigned to this operation, but any such mutable state
should not be concurrently used outside of blocks assigned to this operation.
This property is not atomic.
§Safety
- The returned block’s argument must be a valid pointer or null.
- This might not be thread-safe.
Sourcepub unsafe fn setFetchRecordZoneChangesCompletionBlock(
&self,
fetch_record_zone_changes_completion_block: Option<&DynBlock<dyn Fn(*mut NSError)>>,
)
Available on crate feature block2 only.
pub unsafe fn setFetchRecordZoneChangesCompletionBlock( &self, fetch_record_zone_changes_completion_block: Option<&DynBlock<dyn Fn(*mut NSError)>>, )
block2 only.Setter for fetchRecordZoneChangesCompletionBlock.
This is copied when set.
§Safety
This might not be thread-safe.
Source§impl CKFetchRecordZoneChangesOperation
Methods declared on superclass NSObject.
impl CKFetchRecordZoneChangesOperation
Methods declared on superclass NSObject.
Source§impl CKFetchRecordZoneChangesOperation
Deprecated.
impl CKFetchRecordZoneChangesOperation
Deprecated.
pub unsafe fn initWithRecordZoneIDs_optionsByRecordZoneID( this: Allocated<Self>, record_zone_i_ds: &NSArray<CKRecordZoneID>, options_by_record_zone_id: Option<&NSDictionary<CKRecordZoneID, CKFetchRecordZoneChangesOptions>>, ) -> Retained<Self>
CKRecordZoneID only.Sourcepub unsafe fn optionsByRecordZoneID(
&self,
) -> Option<Retained<NSDictionary<CKRecordZoneID, CKFetchRecordZoneChangesOptions>>>
👎DeprecatedAvailable on crate feature CKRecordZoneID only.
pub unsafe fn optionsByRecordZoneID( &self, ) -> Option<Retained<NSDictionary<CKRecordZoneID, CKFetchRecordZoneChangesOptions>>>
CKRecordZoneID only.Sourcepub unsafe fn setOptionsByRecordZoneID(
&self,
options_by_record_zone_id: Option<&NSDictionary<CKRecordZoneID, CKFetchRecordZoneChangesOptions>>,
)
👎DeprecatedAvailable on crate feature CKRecordZoneID only.
pub unsafe fn setOptionsByRecordZoneID( &self, options_by_record_zone_id: Option<&NSDictionary<CKRecordZoneID, CKFetchRecordZoneChangesOptions>>, )
CKRecordZoneID only.Methods from Deref<Target = CKDatabaseOperation>§
Sourcepub unsafe fn database(&self) -> Option<Retained<CKDatabase>>
Available on crate feature CKDatabase only.
pub unsafe fn database(&self) -> Option<Retained<CKDatabase>>
CKDatabase only.The database on which to perform the operation.
If no database is set,
[self.container privateCloudDatabase]is used. This will also set the container property of the operation’s configuration to match the container of the passed-in database.
This property is not atomic.
§Safety
This might not be thread-safe.
Sourcepub unsafe fn setDatabase(&self, database: Option<&CKDatabase>)
Available on crate feature CKDatabase only.
pub unsafe fn setDatabase(&self, database: Option<&CKDatabase>)
CKDatabase only.Methods from Deref<Target = CKOperation>§
Sourcepub unsafe fn configuration(&self) -> Retained<CKOperationConfiguration>
pub unsafe fn configuration(&self) -> Retained<CKOperationConfiguration>
This defines per-operation configuration settings.
See the CKOperationConfiguration class description for info on how this configuration composes with CKOperationGroup.defaultConfiguration
This property is not atomic.
§Safety
This might not be thread-safe.
Sourcepub unsafe fn setConfiguration(
&self,
configuration: Option<&CKOperationConfiguration>,
)
pub unsafe fn setConfiguration( &self, configuration: Option<&CKOperationConfiguration>, )
Sourcepub unsafe fn group(&self) -> Option<Retained<CKOperationGroup>>
Available on crate feature CKOperationGroup only.
pub unsafe fn group(&self) -> Option<Retained<CKOperationGroup>>
CKOperationGroup only.The group this operation is associated with
This property is not atomic.
§Safety
This might not be thread-safe.
Sourcepub unsafe fn setGroup(&self, group: Option<&CKOperationGroup>)
Available on crate feature CKOperationGroup only.
pub unsafe fn setGroup(&self, group: Option<&CKOperationGroup>)
CKOperationGroup only.Sourcepub unsafe fn operationID(&self) -> Retained<CKOperationID>
pub unsafe fn operationID(&self) -> Retained<CKOperationID>
This is an identifier unique to this CKOperation.
This value is chosen by the system, and will be unique to this instance of a CKOperation. This identifier will be sent to Apple’s servers, and can be used to identify any server-side logging associated with this operation.
This property is not atomic.
§Safety
This might not be thread-safe.
Sourcepub unsafe fn longLivedOperationWasPersistedBlock(
&self,
) -> *mut DynBlock<dyn Fn()>
Available on crate feature block2 only.
pub unsafe fn longLivedOperationWasPersistedBlock( &self, ) -> *mut DynBlock<dyn Fn()>
block2 only.This callback is called after a long lived operation has begun running and is persisted.
Once this callback is called the operation will continue running even if the current process exits.
Each
CKOperationinstance has a private serial queue. This queue is used for all callback block invocations.
This block may share mutable state with other blocks assigned to this operation, but any such mutable state
should not be concurrently used outside of blocks assigned to this operation.
This property is not atomic.
§Safety
This might not be thread-safe.
Sourcepub unsafe fn setLongLivedOperationWasPersistedBlock(
&self,
long_lived_operation_was_persisted_block: Option<&DynBlock<dyn Fn()>>,
)
Available on crate feature block2 only.
pub unsafe fn setLongLivedOperationWasPersistedBlock( &self, long_lived_operation_was_persisted_block: Option<&DynBlock<dyn Fn()>>, )
block2 only.Setter for longLivedOperationWasPersistedBlock.
This is copied when set.
§Safety
This might not be thread-safe.
Sourcepub unsafe fn container(&self) -> Option<Retained<CKContainer>>
👎Deprecated: Use CKOperationConfigurationAvailable on crate feature CKContainer only.
pub unsafe fn container(&self) -> Option<Retained<CKContainer>>
CKContainer only.Sourcepub unsafe fn setContainer(&self, container: Option<&CKContainer>)
👎Deprecated: Use CKOperationConfigurationAvailable on crate feature CKContainer only.
pub unsafe fn setContainer(&self, container: Option<&CKContainer>)
CKContainer only.Sourcepub unsafe fn allowsCellularAccess(&self) -> bool
👎Deprecated: Use CKOperationConfiguration
pub unsafe fn allowsCellularAccess(&self) -> bool
Sourcepub unsafe fn setAllowsCellularAccess(&self, allows_cellular_access: bool)
👎Deprecated: Use CKOperationConfiguration
pub unsafe fn setAllowsCellularAccess(&self, allows_cellular_access: bool)
Sourcepub unsafe fn isLongLived(&self) -> bool
👎Deprecated: Use CKOperationConfiguration
pub unsafe fn isLongLived(&self) -> bool
Sourcepub unsafe fn setLongLived(&self, long_lived: bool)
👎Deprecated: Use CKOperationConfiguration
pub unsafe fn setLongLived(&self, long_lived: bool)
Sourcepub unsafe fn timeoutIntervalForRequest(&self) -> NSTimeInterval
👎Deprecated: Use CKOperationConfiguration
pub unsafe fn timeoutIntervalForRequest(&self) -> NSTimeInterval
Sourcepub unsafe fn setTimeoutIntervalForRequest(
&self,
timeout_interval_for_request: NSTimeInterval,
)
👎Deprecated: Use CKOperationConfiguration
pub unsafe fn setTimeoutIntervalForRequest( &self, timeout_interval_for_request: NSTimeInterval, )
Sourcepub unsafe fn timeoutIntervalForResource(&self) -> NSTimeInterval
👎Deprecated: Use CKOperationConfiguration
pub unsafe fn timeoutIntervalForResource(&self) -> NSTimeInterval
Sourcepub unsafe fn setTimeoutIntervalForResource(
&self,
timeout_interval_for_resource: NSTimeInterval,
)
👎Deprecated: Use CKOperationConfiguration
pub unsafe fn setTimeoutIntervalForResource( &self, timeout_interval_for_resource: NSTimeInterval, )
Methods from Deref<Target = NSOperation>§
pub fn start(&self)
pub fn main(&self)
pub fn isCancelled(&self) -> bool
pub fn cancel(&self)
pub fn isExecuting(&self) -> bool
pub fn isFinished(&self) -> bool
pub fn isConcurrent(&self) -> bool
pub fn isAsynchronous(&self) -> bool
pub fn isReady(&self) -> bool
pub fn addDependency(&self, op: &NSOperation)
pub fn removeDependency(&self, op: &NSOperation)
pub fn dependencies(&self) -> Retained<NSArray<NSOperation>>
pub fn queuePriority(&self) -> NSOperationQueuePriority
Sourcepub fn setQueuePriority(&self, queue_priority: NSOperationQueuePriority)
pub fn setQueuePriority(&self, queue_priority: NSOperationQueuePriority)
Setter for queuePriority.
Sourcepub unsafe fn completionBlock(&self) -> *mut Block<dyn Fn()>
pub unsafe fn completionBlock(&self) -> *mut Block<dyn Fn()>
§Safety
The returned block must be sendable.
Sourcepub unsafe fn setCompletionBlock(
&self,
completion_block: Option<&Block<dyn Fn()>>,
)
pub unsafe fn setCompletionBlock( &self, completion_block: Option<&Block<dyn Fn()>>, )
Setter for completionBlock.
This is copied when set.
§Safety
completion_block block must be sendable.
pub fn waitUntilFinished(&self)
pub fn threadPriority(&self) -> f64
Sourcepub fn setThreadPriority(&self, thread_priority: f64)
👎Deprecated: Not supported
pub fn setThreadPriority(&self, thread_priority: f64)
Setter for threadPriority.
pub fn qualityOfService(&self) -> NSQualityOfService
Sourcepub fn setQualityOfService(&self, quality_of_service: NSQualityOfService)
pub fn setQualityOfService(&self, quality_of_service: NSQualityOfService)
Setter for qualityOfService.
pub fn name(&self) -> Option<Retained<NSString>>
Methods from Deref<Target = NSObject>§
Sourcepub fn doesNotRecognizeSelector(&self, sel: Sel) -> !
pub fn doesNotRecognizeSelector(&self, sel: Sel) -> !
Handle messages the object doesn’t recognize.
See Apple’s documentation for details.
Methods from Deref<Target = AnyObject>§
Sourcepub fn class(&self) -> &'static AnyClass
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());Sourcepub unsafe fn get_ivar<T>(&self, name: &str) -> &Twhere
T: Encode,
👎Deprecated: this is difficult to use correctly, use Ivar::load instead.
pub unsafe fn get_ivar<T>(&self, name: &str) -> &Twhere
T: Encode,
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.
Sourcepub fn downcast_ref<T>(&self) -> Option<&T>where
T: DowncastTarget,
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§
Source§impl AsRef<CKDatabaseOperation> for CKFetchRecordZoneChangesOperation
impl AsRef<CKDatabaseOperation> for CKFetchRecordZoneChangesOperation
Source§fn as_ref(&self) -> &CKDatabaseOperation
fn as_ref(&self) -> &CKDatabaseOperation
Source§impl AsRef<CKOperation> for CKFetchRecordZoneChangesOperation
impl AsRef<CKOperation> for CKFetchRecordZoneChangesOperation
Source§fn as_ref(&self) -> &CKOperation
fn as_ref(&self) -> &CKOperation
Source§impl AsRef<NSOperation> for CKFetchRecordZoneChangesOperation
impl AsRef<NSOperation> for CKFetchRecordZoneChangesOperation
Source§fn as_ref(&self) -> &NSOperation
fn as_ref(&self) -> &NSOperation
Source§impl Borrow<CKDatabaseOperation> for CKFetchRecordZoneChangesOperation
impl Borrow<CKDatabaseOperation> for CKFetchRecordZoneChangesOperation
Source§fn borrow(&self) -> &CKDatabaseOperation
fn borrow(&self) -> &CKDatabaseOperation
Source§impl Borrow<CKOperation> for CKFetchRecordZoneChangesOperation
impl Borrow<CKOperation> for CKFetchRecordZoneChangesOperation
Source§fn borrow(&self) -> &CKOperation
fn borrow(&self) -> &CKOperation
Source§impl Borrow<NSOperation> for CKFetchRecordZoneChangesOperation
impl Borrow<NSOperation> for CKFetchRecordZoneChangesOperation
Source§fn borrow(&self) -> &NSOperation
fn borrow(&self) -> &NSOperation
Source§impl ClassType for CKFetchRecordZoneChangesOperation
impl ClassType for CKFetchRecordZoneChangesOperation
Source§const NAME: &'static str = "CKFetchRecordZoneChangesOperation"
const NAME: &'static str = "CKFetchRecordZoneChangesOperation"
Source§type Super = CKDatabaseOperation
type Super = CKDatabaseOperation
Source§type ThreadKind = <<CKFetchRecordZoneChangesOperation as ClassType>::Super as ClassType>::ThreadKind
type ThreadKind = <<CKFetchRecordZoneChangesOperation as ClassType>::Super as ClassType>::ThreadKind
Source§impl NSObjectProtocol for CKFetchRecordZoneChangesOperation
impl NSObjectProtocol for CKFetchRecordZoneChangesOperation
Source§fn isEqual(&self, other: Option<&AnyObject>) -> bool
fn isEqual(&self, other: Option<&AnyObject>) -> bool
Source§fn hash(&self) -> usize
fn hash(&self) -> usize
Source§fn isKindOfClass(&self, cls: &AnyClass) -> bool
fn isKindOfClass(&self, cls: &AnyClass) -> bool
Source§fn is_kind_of<T>(&self) -> bool
fn is_kind_of<T>(&self) -> bool
isKindOfClass directly, or cast your objects with AnyObject::downcast_ref