Struct VNClassificationObservation

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

Available on crate feature VNObservation only.

VNClassificationObservation returns the classifcation in form of a string.

VNClassificationObservation is the observation returned by VNCoreMLRequests that using a model that is a classifier. A classifier produces an arrary (this can be a single entry) of classifications which are labels (identifiers) and confidence scores.

See also Apple’s documentation

Implementations

impl VNClassificationObservation

pub unsafe fn identifier(&self) -> Retained<NSString>

The is the label or identifier of a classification request. An example classification could be a string like ‘cat’ or ‘hotdog’. The string is defined in the model that was used for the classification. Usually these are technical labels that are not localized and not meant to be used directly to be presented to an end user in the UI.

impl VNClassificationObservation

Methods declared on superclass NSObject.

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

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

impl VNClassificationObservation

PrecisionRecallAdditions. VNClassificationObservation mave have precision/recall curves which can be used to decide on an “optimal” operation point. Precision is a value in the range of [0..1] which represents the fraction of relevant instances among the retrieved instances. Recall is a value in the range of [0..1] which represents the fraction of relevant instances that have been retrieved over the total amount of relevant instances.

pub unsafe fn hasPrecisionRecallCurve(&self) -> bool

Determine whether or not precision/recall curves are available with the observation.

If this property is YES, then all other precision/recall related methods in this addition can be called.

pub unsafe fn hasMinimumRecall_forPrecision( &self, minimum_recall: c_float, precision: c_float, ) -> bool

Determine whether or not the observation’s operation point for a specific precision has a minimum recall value.

Parameter minimumRecall: The minimum recall desired for an operation point.

Parameter precision: The precision value used to select the operation point.

Returns: YES if the recall value for the operation point specified by a precision value has the minimum value; otherwise, NO.

pub unsafe fn hasMinimumPrecision_forRecall( &self, minimum_precision: c_float, recall: c_float, ) -> bool

Determine whether or not the observation’s operation point for a specific recall has a minimum precision value.

Parameter minimumPrecision: The minimum precision desired for an operation point.

Parameter recall: The recall value used to select the operation point.

Returns: YES if the precision value for the operation point specified by a recall value has the minimum value; otherwise, NO.

Methods from Deref<Target = VNObservation>

pub unsafe fn uuid(&self) -> Retained<NSUUID>

The unique identifier assigned to an observation.

pub unsafe fn confidence(&self) -> VNConfidence

Available on crate feature VNTypes only.

The level of confidence normalized to [0, 1] where 1 is most confident. The only exception is results coming from VNCoreMLRequest, where confidence values are forwarded as is from relevant CoreML models

Confidence can always be returned as 1.0 if confidence is not supported or has no meaning

pub unsafe fn timeRange(&self) -> CMTimeRange

Available on crate feature objc2-core-media only.

The duration of the observation reporting when first detected and how long it is valid.

The duration of the observation when used with a sequence of buffers. If a request does not support a timeRange or the timeRange is not known, the start time and duration will be set to 0.

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 VNClassificationObservation

fn as_ref(&self) -> &AnyObject

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

impl AsRef<NSObject> for VNClassificationObservation

fn as_ref(&self) -> &NSObject

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

impl AsRef<VNClassificationObservation> for VNClassificationObservation

fn as_ref(&self) -> &Self

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

impl AsRef<VNObservation> for VNClassificationObservation

fn as_ref(&self) -> &VNObservation

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

impl Borrow<AnyObject> for VNClassificationObservation

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl Borrow<NSObject> for VNClassificationObservation

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl Borrow<VNObservation> for VNClassificationObservation

fn borrow(&self) -> &VNObservation

Immutably borrows from an owned value.

impl ClassType for VNClassificationObservation

const NAME: &'static str = "VNClassificationObservation"

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

type Super = VNObservation

The superclass of this class.

type ThreadKind = <<VNClassificationObservation 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 CopyingHelper for VNClassificationObservation

type Result = VNClassificationObservation

The immutable counterpart of the type, or Self if the type has no immutable counterpart.

impl Debug for VNClassificationObservation

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

Formats the value using the given formatter.

impl Deref for VNClassificationObservation

type Target = VNObservation

The resulting type after dereferencing.

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

Dereferences the value.

impl Hash for VNClassificationObservation

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 VNClassificationObservation

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

where Self: Sized,

Increment the reference count of the receiver.

impl NSCopying for VNClassificationObservation

fn copy(&self) -> Retained<Self::Result>

where Self: Sized + Message + CopyingHelper,

Returns a new instance that’s a copy of the receiver.

unsafe fn copyWithZone(&self, zone: *mut NSZone) -> Retained<Self::Result>

where Self: Sized + Message + CopyingHelper,

Returns a new instance that’s a copy of the receiver.

impl NSObjectProtocol for VNClassificationObservation

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 NSSecureCoding for VNClassificationObservation

unsafe fn supportsSecureCoding() -> bool

where Self: Sized + ClassType,

impl PartialEq for VNClassificationObservation

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 VNClassificationObservation

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

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

impl VNRequestRevisionProviding for VNClassificationObservation

unsafe fn requestRevision(&self) -> NSUInteger

where Self: Sized + Message,

Available on crate feature VNRequestRevisionProviding only.

The revision of the VNRequest subclass that was used to generate the object that implements this protocol.

impl DowncastTarget for VNClassificationObservation

impl Eq for VNClassificationObservation

impl NSCoding for VNClassificationObservation