Struct MPSCNNLossDataDescriptor

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pub struct MPSCNNLossDataDescriptor { /* private fields */ }

Available on crate feature MPSCNNLoss only.

Expand description

Dependencies: This depends on Metal.framework.

The MPSCNNLossDataDescriptor specifies a loss data descriptor. The same descriptor can be used to initialize both the labels and the optional weights data.

Implementations§

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impl MPSCNNLossDataDescriptor

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pub unsafe fn layout(&self) -> MPSDataLayout

Available on crate features MPSNeuralNetwork and MPSCore and MPSImage only.

Data layout of loss data. See MPSImage.h for more information.

This parameter specifies the layout of loss data.

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pub unsafe fn size(&self) -> MTLSize

Available on crate feature MPSNeuralNetwork only.

Size of loss data: (width, height, feature channels}.

This parameter specifies the size of loss data.

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pub unsafe fn bytesPerRow(&self) -> NSUInteger

Available on crate feature MPSNeuralNetwork only.

Row bytes of loss data.

This parameter specifies the row bytes of loss data.

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pub unsafe fn setBytesPerRow(&self, bytes_per_row: NSUInteger)

Available on crate feature MPSNeuralNetwork only.

Setter for bytesPerRow.

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pub unsafe fn bytesPerImage(&self) -> NSUInteger

Available on crate feature MPSNeuralNetwork only.

Slice bytes of loss data.

This parameter specifies the slice bytes of loss data.

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pub unsafe fn setBytesPerImage(&self, bytes_per_image: NSUInteger)

Available on crate feature MPSNeuralNetwork only.

Setter for bytesPerImage.

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

Available on crate feature MPSNeuralNetwork only.

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pub unsafe fn cnnLossDataDescriptorWithData_layout_size( data: &NSData, layout: MPSDataLayout, size: MTLSize, ) -> Option<Retained<MPSCNNLossDataDescriptor>>

Available on crate features MPSNeuralNetwork and MPSCore and MPSImage only.

Make a descriptor loss data. The bytesPerRow and bytesPerImage are automatically calculated assuming a dense array. If it is not a dense array, adjust bytesPerRow and bytesPerImage to the right value by changing properties.

Parameter data: The per-element loss data. The data must be in floating point format.

Parameter layout: The data layout of loss data.

Parameter size: The size of loss data.

Returns: A valid MPSCNNLossDataDescriptor object or nil, if failure.

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impl MPSCNNLossDataDescriptor

Methods declared on superclass NSObject.

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

Available on crate feature MPSNeuralNetwork only.

Methods from Deref<Target = NSObject>§

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pub fn doesNotRecognizeSelector(&self, sel: Sel) -> !

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>§

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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());

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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.

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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`
    }
}