Module objc::rc

Utilities for reference counting Objective-C objects.

The utilities of the rc module provide ARC-like semantics for working with Objective-C’s reference counted objects in Rust. A StrongPtr retains an object and releases the object when dropped. A WeakPtr will not retain the object, but can be upgraded to a StrongPtr and safely fails if the object has been deallocated.

These utilities are not intended to provide a fully safe interface, but can be useful when writing higher-level Rust wrappers for Objective-C code.

For more information on Objective-C’s reference counting, see Apple’s documentation: https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/MemoryMgmt/Articles/MemoryMgmt.html

Example

// StrongPtr will release the object when dropped
let obj = unsafe {
    StrongPtr::new(msg_send![class!(NSObject), new])
};

// Cloning retains the object an additional time
let cloned = obj.clone();
autoreleasepool(|| {
    // Autorelease consumes the StrongPtr, but won't
    // actually release until the end of an autoreleasepool
    cloned.autorelease();
});

// Weak references won't retain the object
let weak = obj.weak();
drop(obj);
assert!(weak.load().is_null());

Structs

• StrongPtr
  A pointer that strongly references an object, ensuring it won’t be deallocated.
• WeakPtr
  A pointer that weakly references an object, allowing to safely check whether it has been deallocated.

Functions

• autoreleasepool
  Execute f in the context of a new autorelease pool. The pool is drained after the execution of f completes.