iOS-BlueCap-Example-06.swift

func read(){
    //read a value from the characteristic
    let readFuture = self.dataCharacteristic?.read(timeout: 5)
    readFuture?.onSuccess { (_) in
        //the value is in the dataValue property
        let s = String(data:(self.dataCharacteristic?.dataValue)!, encoding: .utf8)
        DispatchQueue.main.async {
            self.valueLabel.text = "Read value is \(s)"
            print(self.valueLabel.text!)
        }
    }
    readFuture?.onFailure { (_) in
        self.valueLabel.text = "read error"
    }
}

func write(){
    self.valueToWriteTextField.resignFirstResponder()
    guard let text = self.valueToWriteTextField.text else{
        return;
    }
    //write a value to the characteristic
    let writeFuture = self.dataCharacteristic?.write(data:text.data(using: .utf8)!)
    writeFuture?.onSuccess(completion: { (_) in
        print("write succes")
    })
    writeFuture?.onFailure(completion: { (e) in
        print("write failed")
    })
}