Swift 3-隔离函数

Question

我需要一个函数，它只能调用一次，您必须等到下一个函数可以执行

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);

    }
}

我测试过这样的东西：

var dispQueue = DispatchQueue(label: "commandConvert")
...
private func convert(){
    dispQueue.sync {
         ...

    }
}

但这不管用

Answer 1

前几天我就遇到了这个问题。

您可以使用回调或调度组解决此问题。以下是Dispatch Group解决方案：

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);
                }
             }