The handler `CreateObjcBlockPointerFromHandler` has been added the `objc` module

which facilitates the calling of Objective-C methods that require blocks.

Objective-C blocks are objects defining fragments of code which can be called at

a later date, typically used by methods that require progress callbacks or

completion handlers.

`CreateObjcBlockPointerFromHandler` wraps a LCB handler in an `ObjcBlockPointer`

and returns true on success and false otherwise. In order to call the

`CreateObjcBlockPointerFromHandler`, pass the handler to be wrapped as the first

argument and the variable into which the `ObjcBlockPointer` should be placed as

the second.

private variable sRequestPermissionsCompletionHandler as optional ObjcBlockPointer

private variable sTarget as ScriptObject

public handler AudioLibraryInitialize() returns Boolean

if not CreateObjcBlockPointerFromHandler(RequestPermissionsCompletionHandler, \

sRequestPermissionsCompletionHandler) then

put nothing into sRequestPermissionsCompletionHandler

return false

end if

put the caller into sTarget

return true

end handler

public handler RequestPermissionsCompletionHandler(in pBlock as ObjcBlockPointer, in pGranted as CBool)

post "AudioLibraryRequestPermissionsCallback" to sTarget with [pGranted]

end handler

In the example above, the handler `RequestPermissionsCompletionHandler` is

wrapped by the `ObjcBlockPointer` `sRequestPermissionsCompletionHandler`.

The first parameter of the wrapped handler should be an `ObjcBlockPointer`. The

remaining parameters should match those of the Objective-C block the

`ObjcBlockPointer` will be used with.

Once created, an `ObjcBlockPointer` can be used to call Objective-C methods that

require blocks, passing the created `ObjcBlockPointer` where an Objective-C

block would be expected.

private foreign handler ObjC_AVCaptureDeviceRequestAccessForMediaType(in pMediaType as ObjcId, in pCompletionHandler as ObjcBlockPointer) \

returns nothing \

binds to "objc:AVCaptureDevice.+requestAccessForMediaType:completionHandler:"

public handler AudioLibraryRequestPermissions()

unsafe

ObjC_AVCaptureDeviceRequestAccessForMediaType(StringToNSString("soun"), sRequestPermissionsCompletionHandler)

end unsafe

end handler

In the example above, the handler `AudioLibraryRequestPermissions` uses the

previously created block pointer, `sRequestPermissionsCompletionHandler`, when

calling the `requestAccessForMediaType:completionHandler:` method of the

`AVCaptureDevice` type. The method expects the second argument,

`completionHandler:`, to be a block that takes a single `BOOL` parameter, which

in this case matched the signature of the handler

`RequestPermissionsCompletionHandler`.

The wrapped handler will be called whenever the block is invoked, with the first

parameter being the `ObjcBlockPointer` used to wrap the handler.

In the above example, the `RequestPermissionsCompletionHandler` handler will be

called when the `completionHandler:` block is invoked, which in this case will

be when the request permissions process has completed.

The lifetime of a created `ObjcBlockPointer` is not automatically managed. When

such a value has no more references to it and it is no longer going to be used,

`DeleteObjcBlockPointer` should be used to free the resources used by it.

public handler AudioLibraryFinalize()

if sRequestPermissionsCompletionHandler is not nothing then

DeleteObjcBlockPointer(sRequestPermissionsCompletionHandler)

put nothing into sRequestPermissionsCompletionHandler

end if

end handler