Struct AVCaptionFormatConformer

Source

pub struct AVCaptionFormatConformer { /* private fields */ }

Available on crate feature AVCaptionFormatConformer only.

Expand description

Performs a conversion of canonical caption to conform to a specific format.

Implementations§

Source §

pub unsafe fn captionFormatConformerWithConversionSettings( conversion_settings: &NSDictionary<AVCaptionSettingsKey, AnyObject>, ) -> Retained<Self>

Available on crate feature AVCaptionSettings only.

Returns an instance of AVCaptionFormatConformer that can convert a canonical caption to conform to a specific format.

Parameter conversionSettings: Describes the conversion operation for which the caption is to be conformed.

Returns: A new instance of AVCaptionFormatConformer configured to perform the specified conversion.

§Safety

conversion_settings generic should be of the correct type.

Source

pub unsafe fn initWithConversionSettings( this: Allocated<Self>, conversion_settings: &NSDictionary<AVCaptionSettingsKey, AnyObject>, ) -> Retained<Self>

Available on crate feature AVCaptionSettings only.

Returns an instance of AVCaptionFormatConformer that can convert a canonical caption to conform to a specific format.

Parameter conversionSettings: Describes the conversion operation for which the caption is to be conformed.

Returns: A new instance of AVCaptionFormatConformer configured to perform the specified conversion.

This method throws an exception if the conversion setting’s AVCaptionMediaTypeKey is not equal to AVMediaTypeClosedCaption, or if its AVCaptionMediaSubTypeKey is not equal to kCMClosedCaptionFormatType_CEA608.

§Safety

conversion_settings generic should be of the correct type.

Source

pub unsafe fn conformsCaptionsToTimeRange(&self) -> bool

Specifies whether to conform the time range of a given canonical caption as well.

When set to YES, conforms time range. When set to NO, the time range of the conformed caption will be same as a given canonical caption. In the case of conforming to CAE608 format, AVCaption is encoded so that each CAE608 control code (2 bytes) fits into 1 frame duration (1001/30000). When set to YES and if all the encoded data can not fit inside the canonical caption time range, the caption time range will be extended to fit all the data and will be returned in the conformed AVCaption. The default value is NO.

Source

pub unsafe fn setConformsCaptionsToTimeRange( &self, conforms_captions_to_time_range: bool, )

Setter for conformsCaptionsToTimeRange.

Source

pub unsafe fn conformedCaptionForCaption_error( &self, caption: &AVCaption, ) -> Result<Retained<AVCaption>, Retained<NSError>>

Available on crate feature AVCaption only.

Creates a format-compliant caption that conforms to a specific format by converting a given canonical caption.

Parameter caption: Specifies a canonical caption to be converted.

Parameter outError: A pointer where a NSError object may be returned.

Returns: A format-compliant caption that conforms to a specific format.

Methods from Deref<Target = NSObject>§

Source

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

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>§

Source

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());

Source

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.

Source

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`
    }
}