Why is NSAlert.runModal() crashing when called from within the Task.init { } block ?
Is this a bug. I can upload a sample program if required.
@IBAction func start(_ sender: Any) {
isBusy = true
log("start")
Task.init {
log("sync start")
let (result, message) = await asyncObj.process(5, progress: progressCallback)
isBusy = false
log(message)
log("sync end") // Reports as running in main thread
// CRASHES HERE !
alert = self.dialogOK(question: "Some question", text: "Some thing else")
log("task end") // Reports as running in main thread
}
}
func dialogOK(question: String, text: String) -> NSAlert {
let alert = NSAlert()
alert.messageText = question
alert.informativeText = text
alert.alertStyle = .warning
alert.addButton(withTitle: "OK")
return alert //.runModal() == .alertFirstButtonReturn
}
/// This process MUST run on a background thread - it cannot run on the main thread
/// So how do I force it to run on a background thread ?
func process(_ count: Int, progress: @escaping (Double)->Void) async -> (Bool, String) {
// Still on the main thread here ??
log("1 First part on the main thread ??")
let task = Task.detached { () -> (Bool, String) in
//Thread.sleep(forTimeInterval: 0.1)
log("2 Run a loop in the background")
log(" Thread: \(Thread.isMainThread ? "UI" : "BG")")
var cnt = 0
for i in 0..<count {
Thread.sleep(forTimeInterval: 0.025)// sleep(seconds: 0.1)
log(" i: \(i)")
cnt += 1
progress (Double(cnt)/Double(count)*100)
}
log(" >>>>")
return (true, "Background task Done")
}
let result = await task.value
log("2 First part on the main thread ??")
return result
}