Struct GKStateMachine

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pub struct GKStateMachine { /* private fields */ }

Available on crate feature GKStateMachine only.

Expand description

Models a finite state machine that has a single current state.

Implementations§

Source §

impl GKStateMachine

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pub unsafe fn currentState(&self) -> Option<Retained<GKState>>

Available on crate feature GKState only.

The current state that the state machine is in. Prior to the first called to enterState this is equal to nil.

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pub unsafe fn stateMachineWithStates( states: &NSArray<GKState>, ) -> Retained<Self>

Available on crate feature GKState only.

Creates a state machine with an array of possible states and an initial state.

Parameter states: a list of possible states for this state machine.

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pub unsafe fn initWithStates( this: Allocated<Self>, states: &NSArray<GKState>, ) -> Retained<Self>

Available on crate feature GKState only.

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

Updates the current state machine.

Parameter sec: the time, in seconds, since the last frame

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pub unsafe fn stateForClass( &self, state_class: &AnyClass, ) -> Option<Retained<GKState>>

Available on crate feature GKState only.

Gets the instance of the indicated state class from this state machine. Returns nil if the state does not exist

Parameter stateClass: the class of the state to be retrieved

§Safety

state_class probably has further requirements.

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pub unsafe fn canEnterState(&self, state_class: &AnyClass) -> bool

Returns YES if the indicated class is a a valid next state or if currentState is nil

Parameter stateClass: the class of the state to be tested

§Safety

state_class probably has further requirements.

Source

pub unsafe fn enterState(&self, state_class: &AnyClass) -> bool

Calls canEnterState to check if we can enter the given state and then enters that state if so. [GKState willExitWithNextState:] is called on the old current state. [GKState didEnterWithPreviousState:] is called on the new state.

Parameter stateClass: the class of the state to switch to

Returns: YES if state was entered. NO otherwise.

§Safety

state_class probably has further requirements.

Source §

impl GKStateMachine

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`
    }
}