Struct UIFieldBehavior 

pub struct UIFieldBehavior { /* private fields */ }

Available on crate features UIDynamicBehavior and UIFieldBehavior only.

Apple’s documentation

Implementations

impl UIFieldBehavior

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

pub fn addItem(&self, item: &ProtocolObject<dyn UIDynamicItem>)

pub fn removeItem(&self, item: &ProtocolObject<dyn UIDynamicItem>)

pub fn items(&self) -> Retained<NSArray<ProtocolObject<dyn UIDynamicItem>>>

pub fn position(&self) -> CGPoint

Available on crate feature objc2-core-foundation only.

The position (origin) of the field in the reference coordinate system

pub fn setPosition(&self, position: CGPoint)

Available on crate feature objc2-core-foundation only.

Setter for position.

pub fn region(&self) -> Retained<UIRegion>

Available on crate feature UIRegion only.

The region property is the domain of the field’s effect. No force is applied to objects outside the region. The default region is the infiniteRegion

pub fn setRegion(&self, region: &UIRegion)

Available on crate feature UIRegion only.

Setter for region.

pub fn strength(&self) -> CGFloat

Available on crate feature objc2-core-foundation only.

Strength scaling value. default 1.0

pub fn setStrength(&self, strength: CGFloat)

Available on crate feature objc2-core-foundation only.

Setter for strength.

pub fn falloff(&self) -> CGFloat

Available on crate feature objc2-core-foundation only.

The falloff exponent used to calculate field strength at a distance. Falloff starts at the minimum radius. The default exponent is zero, which results in a uniform field with no falloff.

See: minimumRadius

pub fn setFalloff(&self, falloff: CGFloat)

Available on crate feature objc2-core-foundation only.

Setter for falloff.

pub fn minimumRadius(&self) -> CGFloat

Available on crate feature objc2-core-foundation only.

Minimum radius of effect. Default is very small.

pub fn setMinimumRadius(&self, minimum_radius: CGFloat)

Available on crate feature objc2-core-foundation only.

Setter for minimumRadius.

pub fn direction(&self) -> CGVector

Available on crate feature objc2-core-foundation only.

The direction of the field. If the field is non-directional, a zero vector will be returned

See: linearGravityFieldWithVector:direction

See: velocityFieldWithVector:direction

pub fn setDirection(&self, direction: CGVector)

Available on crate feature objc2-core-foundation only.

Setter for direction.

pub fn smoothness(&self) -> CGFloat

Available on crate feature objc2-core-foundation only.

Fields without a smoothness component will return 0

See: noiseFieldWithSmoothness:smoothness:animationSpeed

See: turbulenceFieldWithSmoothness:smoothness:animationSpeed

pub fn setSmoothness(&self, smoothness: CGFloat)

Available on crate feature objc2-core-foundation only.

Setter for smoothness.

pub fn animationSpeed(&self) -> CGFloat

Available on crate feature objc2-core-foundation only.

Fields that can be animated can have non zero values. A value of 2 will animate twice as fast as a value of 1.

See: noiseFieldWithSmoothness:smoothness:animationSpeed

See: turbulenceFieldWithSmoothness:smoothness:animationSpeed

pub fn setAnimationSpeed(&self, animation_speed: CGFloat)

Available on crate feature objc2-core-foundation only.

Setter for animationSpeed.

pub fn dragField(mtm: MainThreadMarker) -> Retained<Self>

Slows an object proportionally to the object’s velocity. Use this to simulate effects such as friction from motion through the air.

pub fn vortexField(mtm: MainThreadMarker) -> Retained<Self>

Applies a force tangential to the direction from the sample point to the field’s position. The force will be CCW to the direction. Make the strength negative to apply force in the CW direction. Amount is proportional to distance from center and the object’s mass. This can be used to create rotational effects.

pub fn radialGravityFieldWithPosition( position: CGPoint, mtm: MainThreadMarker, ) -> Retained<Self>

Available on crate feature objc2-core-foundation only.

Applies a force in the direction of the origin of the field in local space. To repel objects, use a negative strength. The force is proportional to the distance from the field origin. Varies with the mass of the object according to F = ma

Parameter position: the origin of the field

See: position

pub fn linearGravityFieldWithVector( direction: CGVector, mtm: MainThreadMarker, ) -> Retained<Self>

Available on crate feature objc2-core-foundation only.

Applies a force in the direction of the vector in the local space. To repel objects, use a negative strength. The force is the same everywhere in the field. Varies with the mass of the object according to F = ma

Parameter direction: The direction the force is applied in the x,y plane. The length of the direction vector is multiplied by the field’s strength property to get the final calculated force. All components of the direction vector are used to calculate the length.

See: direction

pub fn velocityFieldWithVector( direction: CGVector, mtm: MainThreadMarker, ) -> Retained<Self>

Available on crate feature objc2-core-foundation only.

Uses the supplied velocity vector for any object entering the field’s region of effect. Velocity fields override the effect of any other acceleration applied to the body.

Parameter direction: The directed velocity that will be applied to the body.

See: direction

pub fn noiseFieldWithSmoothness_animationSpeed( smoothness: CGFloat, speed: CGFloat, mtm: MainThreadMarker, ) -> Retained<Self>

Available on crate feature objc2-core-foundation only.

A time varying differentiable Perlin simplex noise field. By default a smooth noise is calculated, and the field is time varying. To freeze the noise in place, set animationSpeed to 0.0. Mass is ignored.

Parameter smoothness: value of 0 means as noisy as possible, 1 means as smooth as possible

Parameter animationSpeed: is the general field rate of change in Hz

See: smoothness

See: animationSpeed

pub fn turbulenceFieldWithSmoothness_animationSpeed( smoothness: CGFloat, speed: CGFloat, mtm: MainThreadMarker, ) -> Retained<Self>

Available on crate feature objc2-core-foundation only.

Just like Noise, except the strength of the noise is proportional to the velocity of the object in the field.

Parameter smoothness: value of 0 means as noisy as possible, 1 means as smooth as possible

Parameter animationSpeed: is the general field rate of change in Hz

See: smoothness

See: animationSpeed

pub fn springField(mtm: MainThreadMarker) -> Retained<Self>

A Hooke’s law force - a force linearly proportional to distance from the center of the field. An object in this field will oscillate with a period proportional to the inverse of the mass. An example use is to keep objects confined to a particular region.

pub fn electricField(mtm: MainThreadMarker) -> Retained<Self>

A force proportional to the charge on the object. A charge property has been added to UIDynamicItemBehavior to accomplish this. An example use of this field is to make objects behavior differently from one another when they enter a region, or to make an object’s behavior different than its mass based behavior This field models the first part of the Lorentz equation, F = qE

pub fn magneticField(mtm: MainThreadMarker) -> Retained<Self>

The magnetic field is a uniform field in the positive-z direction (coming out of the screen). When the velocity of a charged dynamic item is perpendicular to the uniform magnetic field, the item feels a resulting force normal to both the velocity and the B field. This results CCW circular motion. You can adjust the strength of the B field to be negative which will result in circular motion being CW instead of CCW. An example use of this field is to make objects behavior differently from one another when they enter a region, or to make an object’s behavior different than its mass based behavior. This field models the second part of the Lorentz equation, F = qvB

pub fn fieldWithEvaluationBlock( block: &DynBlock<dyn Fn(NonNull<UIFieldBehavior>, CGPoint, CGVector, CGFloat, CGFloat, NSTimeInterval) -> CGVector>, mtm: MainThreadMarker, ) -> Retained<Self>

Available on crate features block2 and objc2-core-foundation only.

A field force with a custom force evaluator.

Parameter field: the field being evaluated

Parameter position: The location to evaluate the force at

Parameter velocity: The velocity to be considered during force evaluation. Useful for calculating drag.

Parameter mass: The mass to be taken into account during force evaluation

Parameter charge: The charge to be taken into account during force evaluation

Parameter deltaTime: The current time step

impl UIFieldBehavior

Methods declared on superclass NSObject.

pub unsafe fn new(mtm: MainThreadMarker) -> Retained<Self>

Methods from Deref<Target = UIDynamicBehavior>

pub fn addChildBehavior(&self, behavior: &UIDynamicBehavior)

pub fn removeChildBehavior(&self, behavior: &UIDynamicBehavior)

pub fn childBehaviors(&self) -> Retained<NSArray<UIDynamicBehavior>>

pub fn action(&self) -> *mut DynBlock<dyn Fn()>

Available on crate feature block2 only.

pub fn setAction(&self, action: Option<&DynBlock<dyn Fn()>>)

Available on crate feature block2 only.

Setter for action.

This is copied when set.

pub fn willMoveToAnimator(&self, dynamic_animator: Option<&UIDynamicAnimator>)

Available on crate feature UIDynamicAnimator only.

pub fn dynamicAnimator(&self) -> Option<Retained<UIDynamicAnimator>>

Available on crate feature UIDynamicAnimator only.

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

Available on crate feature UIIndirectScribbleInteraction only.

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.

Available on crate feature UIIndirectScribbleInteraction only.

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,

Available on crate feature UIIndirectScribbleInteraction only.

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 AsRef<AnyObject> for UIFieldBehavior

fn as_ref(&self) -> &AnyObject

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

impl AsRef<NSObject> for UIFieldBehavior

fn as_ref(&self) -> &NSObject

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

impl AsRef<UIDynamicBehavior> for UIFieldBehavior

fn as_ref(&self) -> &UIDynamicBehavior

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

impl AsRef<UIFieldBehavior> for UIFieldBehavior

fn as_ref(&self) -> &Self

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

impl Borrow<AnyObject> for UIFieldBehavior

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl Borrow<NSObject> for UIFieldBehavior

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl Borrow<UIDynamicBehavior> for UIFieldBehavior

fn borrow(&self) -> &UIDynamicBehavior

Immutably borrows from an owned value.

impl ClassType for UIFieldBehavior

const NAME: &'static str = "UIFieldBehavior"

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

type Super = UIDynamicBehavior

The superclass of this class.

type ThreadKind = dyn MainThreadOnly

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 Debug for UIFieldBehavior

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

Formats the value using the given formatter.

impl Deref for UIFieldBehavior

type Target = UIDynamicBehavior

The resulting type after dereferencing.

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

Dereferences the value.

impl Hash for UIFieldBehavior

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 Message for UIFieldBehavior

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

where Self: Sized,

Increment the reference count of the receiver.

impl NSObjectProtocol for UIFieldBehavior

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 PartialEq for UIFieldBehavior

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 RefEncode for UIFieldBehavior

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

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

impl DowncastTarget for UIFieldBehavior

impl Eq for UIFieldBehavior