Struct ITLibMediaEntity

Source

pub struct ITLibMediaEntity { /* private fields */ }

Available on crate feature ITLibMediaEntity only.

Expand description

The ITLibMediaEntity class serves as the abstract superclass for ITLibMediaItem and ITLibPlaylist instances. As the superclass, ITLibMediaEntity defines methods used by those subclasses.

Implementations§

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impl ITLibMediaEntity

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pub unsafe fn persistentID(&self) -> Retained<NSNumber>

The unique identifier of this media entity.

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pub unsafe fn valueForProperty( &self, property: &NSString, ) -> Option<Retained<AnyObject>>

Gets the value for a specified media property key.

The media property keys you can use with this property are listed in this document and in Media Item Property Keys and Playlist Property Keys.

Parameter property: The media property key that you want the corresponding value of.

Returns: The value for the media property key.

Source

pub unsafe fn enumerateValuesForProperties_usingBlock( &self, properties: Option<&NSSet<NSString>>, block: &DynBlock<dyn Fn(NonNull<NSString>, NonNull<AnyObject>, NonNull<Bool>)>, )

Available on crate feature block2 only.

Executes a provided block with the fetched values for the given item properties.

Use this method to get property values in a batch fashion. In some cases, enumerating over a set of property keys can be more efficient than fetching each individual property with valueForProperty:. The media property keys you can use with this property are listed in this document and in Media Item Property Keys and Playlist Property Keys.

Parameter properties: A set of keys for the properties that will be enumerated, or nil to enumerate all properties.

Parameter block: A block object that executes for each property in the properties set.

Source

pub unsafe fn enumerateValuesExceptForProperties_usingBlock( &self, properties: Option<&NSSet<NSString>>, block: &DynBlock<dyn Fn(NonNull<NSString>, NonNull<AnyObject>, NonNull<Bool>)>, )

Available on crate feature block2 only.

Executes a provided block with the fetched values for all properties in the entity except for the provided set.

Use this method to get property values in a batch fashion. In some cases, enumerating over a set of property keys can be more efficient than fetching each individual property with valueForProperty:. The media property keys you can use with this property are listed in this document and in Media Item Property Keys and Playlist Property Keys.

Parameter properties: A set of property keys that should NOT be enumerated, or nil to enumerate all properties.

Parameter block: A block object that executes for each property except for the ones in the properties set.

Source §

impl ITLibMediaEntity

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());

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`
    }
}