Struct GKRandomDistribution

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pub struct GKRandomDistribution { /* private fields */ }

Available on crate feature GKRandomDistribution only.

Expand description

A random distribution is a random source itself with a specific mapping from the input source to the output values. The distribution is uniform, meaning there is no bias towards any of the possible outcomes.

Implementations§

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impl GKRandomDistribution

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pub unsafe fn lowestValue(&self) -> NSInteger

The lowest value the distribution will output.

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pub unsafe fn highestValue(&self) -> NSInteger

The highest value the distribution will output.

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pub unsafe fn numberOfPossibleOutcomes(&self) -> NSUInteger

The number of unique possible outcomes, depending on the distribution type this is not always highest - lowest + 1.

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pub unsafe fn initWithRandomSource_lowestValue_highestValue( this: Allocated<Self>, source: &ProtocolObject<dyn GKRandom>, lowest_inclusive: NSInteger, highest_inclusive: NSInteger, ) -> Retained<Self>

Available on crate feature GKRandomSource only.

Initializes a random distribution within the range [lowest, highest] using a source to grab input values from.

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pub unsafe fn nextInt(&self) -> NSInteger

Returns the next integer in the distribution sequence and moves ahead to the next one. The value is in the range of [lowest, highest].

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pub unsafe fn nextIntWithUpperBound( &self, upper_bound: NSUInteger, ) -> NSUInteger

Returns the next unsigned value in the distribution sequence that is less than upperBound. The value never equals or exceeeds upperBounds, and in this case it will also never exceed the highest value of the distribution.

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pub unsafe fn nextUniform(&self) -> c_float

Returns the next uniform float in the random sequence and moves ahead to the next one. The value is in the range of [lowest / higest, 1.0].

The value is quantized to the distribution’s lowest and highest bounds. Thus on a d20 distribution the value is quantized to 5% increments. The output value 0 is not possible to get unless the lowest value bound is also 0 or below.

See: nextInt

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pub unsafe fn nextBool(&self) -> bool

Returns the next true or false value in the distribution sequence and moves ahead to the next one. The value is either nonzero (true) or zero (false). Use this for simple boolean switches in logic that don’t require fuzzy evaluation. For fuzzy evaluation use nextUniform.

By default this is based on the referenced source’s definition of nextBool.

See: GKRandomSource.nextBool

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pub unsafe fn distributionWithLowestValue_highestValue( lowest_inclusive: NSInteger, highest_inclusive: NSInteger, ) -> Retained<Self>

Convenience creation of random distribution within the range [lowest, highest] using an isolated source to grab input values from. This is equivalent to calling alloc followed by initWithSource:lowest:highest:, where source is [[GKRandomSource alloc] init].

See: initWithRandomSource:lowestValue:highestValue:

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pub unsafe fn distributionForDieWithSideCount( side_count: NSInteger, ) -> Retained<Self>

Convenience creation of random distribution with the die like range [1, sideCount] using an isolated source to grab input values from. This is equivalent to calling alloc followed by initWithSource:lowest:highest:, where source is [[GKRandomSource alloc] init].

See: initWithRandomSource:lowestValue:highestValue:

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pub unsafe fn d6() -> Retained<Self>

Convenience creation for the very common d6 range [1, 6] with an isolated random source shielded from outside sources.

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pub unsafe fn d20() -> Retained<Self>

Convenience creation for the very common d20 range [1, 20] with an isolated random source shielded from outside sources.

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impl GKRandomDistribution

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`
    }
}

Trait Implementations§

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