My macOS app shows a representation of the contents of various folders,
so using FSEvents to track modifications from outside the app seemed to
be the way to go. I am running into difficulty with writing the code
with a callback, all in Swift. I must be doing something wrong, as I get
a crash in the callback.
Code in my ViewController class:
let scanTarget = [<the folders I monitor>]
let scanCallback: FSEventStreamCallback = { (streamRef:
ConstFSEventStreamRef, context: UnsafeMutableRawPointer?, count: Int,
streamPtr: UnsafeMutableRawPointer, flags:
UnsafePointer<FSEventStreamEventFlags>?, eventID:
UnsafePointer<FSEventStreamEventId>?) in
// Convert to appropriate pointer
let theController = context?.bindMemory(to:
ViewController.self, capacity: 1)
// The following line crashes with a bad address exception
theController?.pointee.<use the pointer to call a method>
}
var mutableSelf = self
var theContext = FSEventStreamContext(version: 0, info:
&mutableSelf, retain: nil, release: nil, copyDescription: nil)
let scanInterval: CFTimeInterval = 5.0
eventStream = FSEventStreamCreate(nil, scanCallback,
&theContext, scanTarget as CFArray,
FSEventStreamEventId(kFSEventStreamEventIdSinceNow), scanInterval,
FSEventStreamCreateFlags(kFSEventStreamCreateFlagUseCFTypes))
The pointer I get back (as theController.pointee) is not valid, so I'm
obviously doing this incorrectly. I had an idea that the mutableSelf
variable should be a class variable, but that didn't really help.
So, how do I get a pointer to self inside the callback?
--
John Brownie
In Finland on furlough from SIL Papua New Guinea
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