Struct AVMIDIPlayer

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pub struct AVMIDIPlayer { /* private fields */ }

Available on crate feature AVMIDIPlayer only.

Expand description

A player for music file formats (MIDI, iMelody).

Implementations§

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impl AVMIDIPlayer

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pub unsafe fn initWithContentsOfURL_soundBankURL_error( this: Allocated<Self>, in_url: &NSURL, bank_url: Option<&NSURL>, ) -> Result<Retained<Self>, Retained<NSError>>

Create a player with the contents of the file specified by the URL.

‘bankURL’ should contain the path to a SoundFont2 or DLS bank to be used by the MIDI synthesizer. For OSX it can be set to nil for the default, but for iOS it must always refer to a valid bank file.

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pub unsafe fn initWithData_soundBankURL_error( this: Allocated<Self>, data: &NSData, bank_url: Option<&NSURL>, ) -> Result<Retained<Self>, Retained<NSError>>

Create a player with the contents of the data object

‘bankURL’ should contain the path to a SoundFont2 or DLS bank to be used by the MIDI synthesizer. For OSX it can be set to nil for the default, but for iOS it must always refer to a valid bank file.

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pub unsafe fn prepareToPlay(&self)

Get ready to play the sequence by prerolling all events

Happens automatically on play if it has not already been called, but may produce a delay in startup.

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pub unsafe fn play(&self, completion_handler: AVMIDIPlayerCompletionHandler)

Available on crate feature block2 only.

Play the sequence.

§Safety

completion_handler must be a valid pointer or null.

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pub unsafe fn stop(&self)

Stop playing the sequence.

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pub unsafe fn duration(&self) -> NSTimeInterval

The length of the currently loaded file in seconds.

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pub unsafe fn isPlaying(&self) -> bool

Indicates whether or not the player is playing

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pub unsafe fn rate(&self) -> c_float

The playback rate of the player

1.0 is normal playback rate. Rate must be > 0.0.

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pub unsafe fn setRate(&self, rate: c_float)

Setter for rate.

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pub unsafe fn currentPosition(&self) -> NSTimeInterval

The current playback position in seconds

Setting this positions the player to the specified time. No range checking on the time value is done. This can be set while the player is playing, in which case playback will resume at the new time.

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pub unsafe fn setCurrentPosition(&self, current_position: NSTimeInterval)

Setter for currentPosition.

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impl AVMIDIPlayer

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`
    }
}