Struct HMCharacteristic

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pub struct HMCharacteristic { /* private fields */ }

Available on crate feature HMCharacteristic only.

Expand description

Represent a characteristic on a service of an accessory.

Implementations§

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impl HMCharacteristic

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

The type of the characteristic, e.g. HMCharacteristicTypePowerState.

This property is not atomic.

§Safety

This might not be thread-safe.

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

The localized description of the characteristic.

This property is not atomic.

§Safety

This might not be thread-safe.

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pub unsafe fn service(&self) -> Option<Retained<HMService>>

Available on crate feature HMService only.

Service that contains this characteristic.

This property is not atomic.

§Safety

This might not be thread-safe.

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pub unsafe fn properties(&self) -> Retained<NSArray<NSString>>

Array that describes the properties of the characteristic.

This value corresponds to the properties associated with this characteristic. The contents of the array are one or more HMCharacteristicProperty constants.

This property is not atomic.

§Safety

This might not be thread-safe.

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pub unsafe fn metadata(&self) -> Option<Retained<HMCharacteristicMetadata>>

Available on crate feature HMCharacteristicMetadata only.

Meta data associated with the characteristic.

This property is not atomic.

§Safety

This might not be thread-safe.

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pub unsafe fn value(&self) -> Option<Retained<AnyObject>>

The value of the characteristic.

The value is a cached value that may have been updated as a result of prior interaction with the accessory.

This property is not atomic.

§Safety

This might not be thread-safe.

Source

pub unsafe fn isNotificationEnabled(&self) -> bool

Specifies whether the characteristic has been enabled to send notifications.

This property is reset to NO if the reachability of the accessory is NO.

This property is not atomic.

§Safety

This might not be thread-safe.

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pub unsafe fn uniqueIdentifier(&self) -> Retained<NSUUID>

A unique identifier for the characteristic.

This property is not atomic.

§Safety

This might not be thread-safe.

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pub unsafe fn writeValue_completionHandler( &self, value: Option<&AnyObject>, completion: &DynBlock<dyn Fn(*mut NSError)>, )

Available on crate feature block2 only.

Modifies the value of the characteristic.

Parameter value: The value to be written.

Parameter completion: Block that is invoked once the request is processed. The NSError provides more information on the status of the request, error will be nil on success.

The value being written is validated against the metadata, format and permissions. The value written may be bounded by metadata for characteristics with int and float format. If validation fails, the error provided to the completion handler indicates the type of failure.

§Safety

value should be of the correct type.

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pub unsafe fn readValueWithCompletionHandler( &self, completion: &DynBlock<dyn Fn(*mut NSError)>, )

Available on crate feature block2 only.

Reads the value of the characteristic. The updated value can be read from the ‘value’ property of the characteristic.

Parameter completion: Block that is invoked once the request is processed. The NSError provides more information on the status of the request, error will be nil on success.

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pub unsafe fn enableNotification_completionHandler( &self, enable: bool, completion: &DynBlock<dyn Fn(*mut NSError)>, )

Available on crate feature block2 only.

Enables/disables notifications or indications for the value of a specified characteristic.

Parameter enable: A Boolean value indicating whether you wish to receive notifications or indications whenever the characteristic’s value changes.

Parameter completion: Block that is invoked once the request is processed. The NSError provides more information on the status of the request, error will be nil on success.

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pub unsafe fn updateAuthorizationData_completionHandler( &self, data: Option<&NSData>, completion: &DynBlock<dyn Fn(*mut NSError)>, )

Available on crate feature block2 only.

Sets/clears authorization data used when writing to the characteristic.

Parameter data: New authorization data to use. Specify nil to remove authorization data.

Parameter completion: Block that is invoked once the request is processed. The NSError provides more information on the status of the request, error will be nil on success.

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

👎Deprecated: HMCharacteristic objects are created by their parent container objects. Directly creating them is not supported.

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impl HMCharacteristic

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`
    }
}