Struct GKComponentSystem 

pub struct GKComponentSystem<ComponentType: ?Sized = AnyObject> { /* private fields */ }

Available on crate feature GKComponent only.

A component system is a homogeneous collection of components that are intended to be called at the same time. The system is homogeneous, meaning it only allows members of the same class into the system.

See also Apple’s documentation

Implementations

impl<ComponentType: ?Sized + Message + AsRef<GKComponent>> GKComponentSystem<ComponentType>

pub unsafe fn cast_unchecked<NewComponentType: ?Sized + Message + AsRef<GKComponent>>( &self, ) -> &GKComponentSystem<NewComponentType>

Unchecked conversion of the generic parameter.

Safety

The generic must be valid to reinterpret as the given type.

impl<ComponentType: Message + AsRef<GKComponent>> GKComponentSystem<ComponentType>

pub unsafe fn componentClass(&self) -> &'static AnyClass

The collection’s component class. Any selector the component supports can be called on the system and it will be forwarded to each of the components in the collection.

pub unsafe fn components(&self) -> Retained<NSArray<ComponentType>>

The array of components currently in the system.

pub unsafe fn objectAtIndexedSubscript( &self, idx: NSUInteger, ) -> Retained<ComponentType>

Supports getting components via a [] subscript.

pub unsafe fn initWithComponentClass( this: Allocated<Self>, cls: &AnyClass, ) -> Retained<Self>

Initializes a system for the given component class. The receiver can now only accept components of the given class.

Safety

cls probably has further requirements.

pub unsafe fn addComponent(&self, component: &ComponentType)

Adds a component to the system. The component must be of the same class as the system’s componentClass. The component is added to the tail of the collection and will be processed after components that were added before it.

Throws a if the component added is not a kind of the system’s componentClass.

pub unsafe fn addComponentWithEntity(&self, entity: &GKEntity)

Available on crate feature GKEntity only.

Adds the supported component from the entity’s component collection. This is conceptually the same as the pseudo-code:

for (GKComponent *component in entity.components) if (component.class == system.componentClass) [system addComponent:component]

See: GKEntity.components

pub unsafe fn removeComponentWithEntity(&self, entity: &GKEntity)

Available on crate feature GKEntity only.

Removes the supported component from the entity’s component collection This is conceptually the same as the pseudo-code:

for (GKComponent *component in entity.components) if (component.class == system.componentClass) [system removeComponent:component]

pub unsafe fn removeComponent(&self, component: &ComponentType)

Removes a component from the system

Does nothing if the component is not in this system

pub unsafe fn updateWithDeltaTime(&self, seconds: NSTimeInterval)

Updates each component with the given delta time since the last update. Each component thus performs its time based logic with a single message.

pub unsafe fn classForGenericArgumentAtIndex( &self, index: NSUInteger, ) -> &'static AnyClass

Returns the class of the specified generic index

impl<ComponentType: Message + AsRef<GKComponent>> GKComponentSystem<ComponentType>

Methods declared on superclass NSObject.

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

pub unsafe fn new() -> Retained<Self>

Methods from Deref<Target = NSObject>

pub fn doesNotRecognizeSelector(&self, sel: Sel) -> !

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>

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());

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.

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`
    }
}

Trait Implementations

impl<ComponentType: ?Sized + Message> AsRef<AnyObject> for GKComponentSystem<ComponentType>

fn as_ref(&self) -> &AnyObject

Converts this type into a shared reference of the (usually inferred) input type.

impl<ComponentType: ?Sized + Message> AsRef<GKComponentSystem<ComponentType>> for GKComponentSystem<ComponentType>

fn as_ref(&self) -> &Self

Converts this type into a shared reference of the (usually inferred) input type.

impl<ComponentType: ?Sized + Message> AsRef<NSObject> for GKComponentSystem<ComponentType>

fn as_ref(&self) -> &NSObject

Converts this type into a shared reference of the (usually inferred) input type.

impl<ComponentType: ?Sized + Message> Borrow<AnyObject> for GKComponentSystem<ComponentType>

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl<ComponentType: ?Sized + Message> Borrow<NSObject> for GKComponentSystem<ComponentType>

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl<ComponentType: ?Sized + Message> ClassType for GKComponentSystem<ComponentType>

const NAME: &'static str = "GKComponentSystem"

The name of the Objective-C class that this type represents.

type Super = NSObject

The superclass of this class.

type ThreadKind = <<GKComponentSystem<ComponentType> as ClassType>::Super as ClassType>::ThreadKind

Whether the type can be used from any thread, or from only the main thread.

fn class() -> &'static AnyClass

Get a reference to the Objective-C class that this type represents.

fn as_super(&self) -> &Self::Super

Get an immutable reference to the superclass.

impl<ComponentType: ?Sized> Debug for GKComponentSystem<ComponentType>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<ComponentType: ?Sized + Message> Deref for GKComponentSystem<ComponentType>

type Target = NSObject

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<ComponentType: ?Sized> Hash for GKComponentSystem<ComponentType>

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<ComponentType: ?Sized + Message> Message for GKComponentSystem<ComponentType>

fn retain(&self) -> Retained<Self>

where Self: Sized,

Increment the reference count of the receiver.

impl<ComponentType: ?Sized + AsRef<GKComponent>> NSFastEnumeration for GKComponentSystem<ComponentType>

unsafe fn countByEnumeratingWithState_objects_count( &self, state: NonNull<NSFastEnumerationState>, buffer: NonNull<*mut AnyObject>, len: usize, ) -> usize

where Self: Sized + Message,

Safety

impl<ComponentType: ?Sized + AsRef<GKComponent>> NSObjectProtocol for GKComponentSystem<ComponentType>

fn isEqual(&self, other: Option<&AnyObject>) -> bool

where Self: Sized + Message,

Check whether the object is equal to an arbitrary other object.

fn hash(&self) -> usize

where Self: Sized + Message,

An integer that can be used as a table address in a hash table structure.

fn isKindOfClass(&self, cls: &AnyClass) -> bool

where Self: Sized + Message,

Check if the object is an instance of the class, or one of its subclasses.

fn is_kind_of<T>(&self) -> bool

where T: ClassType, Self: Sized + Message,

👎Deprecated: use isKindOfClass directly, or cast your objects with AnyObject::downcast_ref

Check if the object is an instance of the class type, or one of its subclasses.

fn isMemberOfClass(&self, cls: &AnyClass) -> bool

where Self: Sized + Message,

Check if the object is an instance of a specific class, without checking subclasses.

fn respondsToSelector(&self, aSelector: Sel) -> bool

where Self: Sized + Message,

Check whether the object implements or inherits a method with the given selector.

fn conformsToProtocol(&self, aProtocol: &AnyProtocol) -> bool

where Self: Sized + Message,

Check whether the object conforms to a given protocol.

fn description(&self) -> Retained<NSObject>

where Self: Sized + Message,

A textual representation of the object.

fn debugDescription(&self) -> Retained<NSObject>

where Self: Sized + Message,

A textual representation of the object to use when debugging.

fn isProxy(&self) -> bool

where Self: Sized + Message,

Check whether the receiver is a subclass of the NSProxy root class instead of the usual NSObject.

fn retainCount(&self) -> usize

where Self: Sized + Message,

The reference count of the object.

impl<ComponentType: ?Sized> PartialEq for GKComponentSystem<ComponentType>

fn eq(&self, other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<ComponentType: ?Sized + Message> RefEncode for GKComponentSystem<ComponentType>

const ENCODING_REF: Encoding = <NSObject as ::objc2::RefEncode>::ENCODING_REF

The Objective-C type-encoding for a reference of this type.

impl DowncastTarget for GKComponentSystem<AnyObject>

impl<ComponentType: ?Sized> Eq for GKComponentSystem<ComponentType>