Struct MPNowPlayingInfoLanguageOption

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pub struct MPNowPlayingInfoLanguageOption { /* private fields */ }

Available on crate feature MPNowPlayingInfoLanguageOption only.

Expand description

Represents a single language option option.

Implementations§

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impl MPNowPlayingInfoLanguageOption

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pub unsafe fn initWithType_languageTag_characteristics_displayName_identifier( this: Allocated<Self>, language_option_type: MPNowPlayingInfoLanguageOptionType, language_tag: &NSString, language_option_characteristics: Option<&NSArray<NSString>>, display_name: &NSString, identifier: &NSString, ) -> Retained<Self>

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pub unsafe fn isAutomaticLegibleLanguageOption(&self) -> bool

Represents a special case that is used to represent the best legible language option based on system preferences. See AVPlayerItem-selectMediaOptionAutomaticallyInMediaSelectionGroup

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pub unsafe fn isAutomaticAudibleLanguageOption(&self) -> bool

Represents a special case that is used to represent the best audible language option based on system preferences. See AVPlayerItem-selectMediaOptionAutomaticallyInMediaSelectionGroup

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pub unsafe fn languageOptionType(&self) -> MPNowPlayingInfoLanguageOptionType

The type of language option.

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

The IETF BCP 47 language tag. A nil languageTag reprsents that this option should be disabled. A languageTag with the value of MPLangaugeOptionAutoLangaugeTag represents that the best langauge based on the system preferences should be used.

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pub unsafe fn languageOptionCharacteristics( &self, ) -> Option<Retained<NSArray<NSString>>>

Characteristics describing the content of the language options. See the LanguageOptionCharacteristics for the most commonly used values.

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

A user presentable display name for this option.

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

A unique identifier representing this option.

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impl MPNowPlayingInfoLanguageOption

Methods declared on superclass NSObject.

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

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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`
    }
}