Struct objc2::foundation::NSValue
source · #[repr(C)]pub struct NSValue { /* private fields */ }Expand description
A container wrapping any encodable type as an Obective-C object.
Since Objective-C collections like NSArray can only contain
objects, it is common to wrap pointers or structures like NSRange.
Note that creating NSValues is not unsafe, but almost all usage of
it is, since we cannot guarantee that the type that was used to
construct it is the same as the expected output type.
See also the NSNumber subclass for when you want to wrap numbers.
See Apple’s documentation for more information.
Implementations§
source§impl NSValue
impl NSValue
Creation methods.
sourcepub fn new<T: 'static + Copy + Encode>(value: T) -> Id<Self, Shared>
pub fn new<T: 'static + Copy + Encode>(value: T) -> Id<Self, Shared>
Create a new NSValue containing the given type.
Be careful when using this since you may accidentally pass a reference when you wanted to pass a concrete type instead.
Examples
Create an NSValue containing an NSPoint.
use objc2::foundation::{NSPoint, NSValue};
let val = NSValue::new::<NSPoint>(NSPoint::new(1.0, 1.0));source§impl NSValue
impl NSValue
Getter methods.
sourcepub unsafe fn get<T: 'static + Copy + Encode>(&self) -> T
pub unsafe fn get<T: 'static + Copy + Encode>(&self) -> T
Retrieve the data contained in the NSValue.
Note that this is broken on GNUStep for some types, see gnustep/libs-base#216.
Safety
The type of T must be what the NSValue actually stores, and any
safety invariants that the value has must be upheld.
Note that it may be, but is not always, enough to simply check whether
contains_encoding returns true. For example, NonNull<T> have
the same encoding as *const T, but NonNull<T> is clearly not
safe to return from this function even if you’ve checked the encoding
beforehand.
Examples
Store a pointer in NSValue, and retrieve it again afterwards.
use std::ffi::c_void;
use std::ptr;
use objc2::foundation::NSValue;
let val = NSValue::new::<*const c_void>(ptr::null());
// SAFETY: The value was just created with a pointer
let res = unsafe { val.get::<*const c_void>() };
assert!(res.is_null());pub fn get_range(&self) -> Option<NSRange>
pub fn get_point(&self) -> Option<NSPoint>
pub fn get_size(&self) -> Option<NSSize>
pub fn get_rect(&self) -> Option<NSRect>
pub fn encoding(&self) -> Option<&str>
pub fn contains_encoding<T: 'static + Copy + Encode>(&self) -> bool
Methods from Deref<Target = NSObject>§
sourcepub fn is_kind_of<T: ClassType>(&self) -> bool
pub fn is_kind_of<T: ClassType>(&self) -> bool
Check if the object is an instance of the class, or one of it’s subclasses.
See Apple’s documentation for more details on what you may (and what you may not) do with this information.
Methods from Deref<Target = Object>§
sourcepub unsafe fn ivar_ptr<T: Encode>(&self, name: &str) -> *mut T
pub unsafe fn ivar_ptr<T: Encode>(&self, name: &str) -> *mut T
Returns a pointer to the instance variable / ivar with the given name.
This is similar to UnsafeCell::get, see that for more information
on what is and isn’t safe to do.
Usually you will have defined the instance variable yourself with
ClassBuilder::add_ivar, the type of the ivar T must match the
type used in that.
Attempting to access or modify private implementation details of a class that you do no control using this is not supported, and may invoke undefined behaviour.
Library implementors are strongly encouraged to expose a safe interface to the ivar.
Panics
May panic if the object has no ivar with the given name. May also
panic if the type encoding of the ivar differs from the type encoding
of T.
This should purely seen as help while debugging and is not guaranteed
(e.g. it may be disabled when debug_assertions are off).
Safety
The object must have an instance variable with the given name, and it
must be of type T. Any invariants that the object have assumed about
the value of the instance variable must not be violated.
No thread syncronization is done on accesses to the variable, so you must ensure that any access to the returned pointer do not cause data races, and that Rust’s mutability rules are not otherwise violated.
sourcepub unsafe fn ivar<T: Encode>(&self, name: &str) -> &T
pub unsafe fn ivar<T: Encode>(&self, name: &str) -> &T
Returns a reference to the instance variable with the given name.
See Object::ivar_ptr for more information, including on when this
panics.
Safety
The object must have an instance variable with the given name, and it
must be of type T.
No thread syncronization is done, so you must ensure that no other
thread is concurrently mutating the variable. This requirement can be
considered upheld if all mutation happens through Object::ivar_mut
(since that takes &mut self).
sourcepub unsafe fn get_ivar<T: Encode>(&self, name: &str) -> &T
👎Deprecated: Use Object::ivar instead.
pub unsafe fn get_ivar<T: Encode>(&self, name: &str) -> &T
Object::ivar instead.sourcepub unsafe fn ivar_mut<T: Encode>(&mut self, name: &str) -> &mut T
pub unsafe fn ivar_mut<T: Encode>(&mut self, name: &str) -> &mut T
Returns a mutable reference to the ivar with the given name.
See Object::ivar_ptr for more information, including on when this
panics.
Safety
The object must have an instance variable with the given name, and it
must be of type T.
This access happens through &mut self, which means we know it to be
the only reference, hence you do not need to do any work to ensure
that data races do not happen.
sourcepub unsafe fn get_mut_ivar<T: Encode>(&mut self, name: &str) -> &mut T
👎Deprecated: Use Object::ivar_mut instead.
pub unsafe fn get_mut_ivar<T: Encode>(&mut self, name: &str) -> &mut T
Object::ivar_mut instead.sourcepub unsafe fn set_ivar<T: Encode>(&mut self, name: &str, value: T)
pub unsafe fn set_ivar<T: Encode>(&mut self, name: &str, value: T)
Sets the value of the ivar with the given name.
This is just a helpful shorthand for Object::ivar_mut, see that
for more information.
Safety
Same as Object::ivar_mut.