Struct ARQuickLookPreviewItem

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

Available on crate features ARQuickLookPreviewItem and objc2 only.

Expand description

Apple’s documentation

Implementations§

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impl ARQuickLookPreviewItem

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pub unsafe fn initWithFileAtURL( this: Allocated<Self>, url: &NSURL, ) -> Retained<Self>

Available on crate feature objc2-foundation only.

Creates an object representing the 3D content that will be previewed in AR Quick Look.

This object will be previewed in AR Quick Look using the default behavior:

Start in Object mode without camera passthrough
Display the Share button for 3D content sharing
Allow scaling content in both Object and AR mode

This is a promise to the ARQuickLookPreviewItem class that the URL points to a 3D content file. This class does not deal with the file’s existence or content, and leaves it up to QuickLook to handle and process the URL.

Parameter url: A file URL to 3D content file (e.g. usdz).

Returns: The preview object to display in AR Quick Look.

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pub unsafe fn canonicalWebPageURL(&self) -> Option<Retained<NSURL>>

Available on crate feature objc2-foundation only.

An optional canonical web page URL for the 3D content that will be shared.

If this is supplied, the URL to the canonical web page is shared instead of the 3D content file. For example, providing https://developer.apple.com/arkit/gallery/ as the canonical web page URL string will be shared via the Share button. If the web page URL string is malformed or not provided, then AR Quick Look will default to sharing the 3D content.

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pub unsafe fn setCanonicalWebPageURL( &self, canonical_web_page_url: Option<&NSURL>, )

Available on crate feature objc2-foundation only.

Setter for canonicalWebPageURL.

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pub unsafe fn allowsContentScaling(&self) -> bool

Whether or not AR Quick Look allows content scaling in AR mode. Defaults to YES which allows scaling content in AR mode.

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pub unsafe fn setAllowsContentScaling(&self, allows_content_scaling: bool)

Setter for allowsContentScaling.

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

Unavailable

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

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`
    }
}