Struct SNAudioFileAnalyzer

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pub struct SNAudioFileAnalyzer { /* private fields */ }

Available on crate feature SNAnalyzer only.

Expand description

Analyzes an audio file and provides analysis results to the client

Implementations§

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impl SNAudioFileAnalyzer

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

Creates a new analyzer

Parameters:
url: The url for the audio file to be analyzed
error: On input, a pointer to an error object. If an error occurs, this pointer is set to an actual error object containing the error information. You may specify nil for this parameter if you do not want the error information.

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

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pub unsafe fn addRequest_withObserver_error( &self, request: &ProtocolObject<dyn SNRequest>, observer: &ProtocolObject<dyn SNResultsObserving>, ) -> Result<(), Retained<NSError>>

Available on crate features SNRequest and SNResult only.

Adds a new analysis request to the analyzer

Parameters:
request: An audio analysis request to be performed on the audio stream
observer: The object that will receive the analysis results for the supplied request. The observer is weakly retained by the analyzer.
error On input, a pointer to an error object. If an error occurs, this pointer is set to an actual error object containing the error information. You may specify nil for this parameter if you do not want the error information.
Returns: YES if the request was successfully added, and NO otherwise.

If addRequest is called while the file is being processed, an error will be returned.

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pub unsafe fn removeRequest(&self, request: &ProtocolObject<dyn SNRequest>)

Available on crate feature SNRequest only.

Removes an existing analysis request from the analyzer

Parameter request: An audio analysis request to be removed

Requests can be removed while analysis is in progress. Once the removeRequest method returns, the previously registered observer will not receive any more callbacks.

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pub unsafe fn removeAllRequests(&self)

Removes all requests from the analyzer

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pub unsafe fn analyze(&self)

Analyzes the audio file synchronously

This function executes synchronously. Any errors produced during analysis will flow downstream to the request observers. This method may block for a long period of time, so be careful to ensure this call does not block UI or other important tasks.

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pub unsafe fn analyzeWithCompletionHandler( &self, completion_handler: &DynBlock<dyn Fn(Bool)>, )

Available on crate feature block2 only.

Analyzes the audio file asynchronously

This function executes asynchronously, calling the completion after the entire file has completed analysis. Any errors produced during analysis will flow downstream to the request observers. If the cancelAnalysis method is called, the completionHandler will still be called, but with didReachEndOfFile set to NO.

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pub unsafe fn cancelAnalysis(&self)

Cancels any in-progress analysis of the audio file

This function executes asynchronously, and will trigger the completion handler provided in the analyzeWithCompletionHandler method after the cancellation is complete.

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impl SNAudioFileAnalyzer

Methods declared on superclass NSObject.

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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`
    }
}