Swift 3 - Isolate a function - swift3

Question

I need a function, which can only be called once, and you have to wait until the next one can be executed
private func receive(){
var inputBuffer = Array<UInt8>(repeating: 0, count: BUFFER_MAX);
let bytesRead = self.inputStream.read(&inputBuffer, maxLength: BUFFER_MAX);
if(bytesRead > 0){
let string = convertToString(byteArray: inputBuffer, length: bytesRead);
// Call if previous is finished
CommandHandler.convert(string);
}
}
I have tested something like this:
var dispQueue = DispatchQueue(label: "commandConvert")
...
private func convert(){
dispQueue.sync {
...
}
}
but this doesn't work

Answer 1

I just had this issue the other day.
You can solve this using a callback or a Dispatch Group. Here is the Dispatch Group solution:
class test {
let myDispatchGroup = DispatchGroup()
func receive () {
myDispatchGroup.enter()
var inputBuffer = Array<UInt8>(repeating: 0, count: BUFFER_MAX);
let bytesRead = self.inputStream.read(&inputBuffer, maxLength: BUFFER_MAX);
if(bytesRead > 0){
let string = convertToString(byteArray: inputBuffer, length: bytesRead);
myDispatchGroup.leave()
}
myDispatchGroup.notify(queue: DispatchQueue.main) {
// Call if previous is finished
CommandHandler.convert(string);
}
}