Some suggestions regarding objc2-foundation and block2

[libark]

1. When using NSArray or NSDictionary, their values are usually generic types, so they need to be defined using AnyObject, such as NSMutableDictionary::<NSString, AnyObject>. However, for types like NSNumber, multiple calls to into_super or unsafe methods such as Id::cast are required to convert them to AnyObject. Considering the frequency of this operation, could a safe method be provided to complete the conversion from NSNumber to AnyObject in one step?

2. When using many Apple frameworks, it is necessary to pass the static CFString exported from the framework to NSString. Could a method be added for NSString, create NString from a raw pointer?

3. When using block2, all parameter and return value types must implement Encode trait, but many Apple frameworks do not use Objective-C interfaces and types. Could a feature be added to block2 to allow it to be used in C interface framework wrappers, replace block?

[madsmtm]

Thanks for the review!

1. When using NSArray or NSDictionary, their values are usually generic types, so they need to be defined using AnyObject, such as NSMutableDictionary::<NSString, AnyObject>. However, for types like NSNumber, multiple calls to into_super or unsafe methods such as Id::cast are required to convert them to AnyObject. Considering the frequency of this operation, could a safe method be provided to complete the conversion from NSNumber to AnyObject in one step?

This would indeed be very nice, it's tracked in #518.

2. When using many Apple frameworks, it is necessary to pass the static CFString exported from the framework to NSString. Could a method be added for NSString, create NString from a raw pointer?

Hmm, the issue is that the CFString is from core-foundation, and I would like to avoid a dependency on that if possible. The layout of NSString is guaranteed though, so creating it from a raw pointer is fairly simple:

let s: CFString = ...;
let ptr: CFStringRef = s.as_concrete_TypeRef();
let ptr: *const NSString = s.cast();
// SAFETY: CFString is toll-free bridged with NSString
let s: &NSString = unsafe { ptr.as_ref().unwrap() };

3. When using block2, all parameter and return value types must implement Encode trait, but many Apple frameworks do not use Objective-C interfaces and types. Could a feature be added to block2 to allow it to be used in C interface framework wrappers, replace block?

The problem here is that in the future, I'd like to use these encodings to emit block encodings properly, which is used by some methods, see #442 (and #434 for a workaround).

Specifically for core-foundation, you can use something like:

#[repr(transparent)]
struct CustomCFStringRef(CFStringRef);

// SAFETY: `CustomCFStringRef` is `#[repr(transparent)]` over `CFStringRef`
unsafe impl Encode for CustomCFStringRef {
    const ENCODING: Encoding = Encoding::Pointer(&Encoding::Struct("__CFString", &[]));
}

And pass CustomCFStringRef to/from the block.

[madsmtm]

I've added more detailed documentation on interop with core-foundation in eb39164