iOS Application not Writing to BLE Mini - ios

Question

I am designing an application which will communicate with a TI LaunchPad through a BLE Mini by utilizing CoreBluetooth, however I am struggling to transmit data between my iPhone and the Red Bear BLE Mini. Currently, I am trying to send a command which will instruct the Launchpad to turn an LED on and off. I have implemented all of the CoreBluetooth methods and confirmed that I am connected to the BLE Mini. I also have discovered this device's singular service and the five characteristics associated with this device with my iPhone application, so I know I am connected to the device. After confirming this connection, I attempted to write to the write characteristic, but I'm not sure if I wrote to this characteristic properly. Also, I'm not sure how I should be encoding the data. I have tried both ascii and utf8. Here is what I wrote:
let string = "LED-ON"
let data = string.data(using: .ascii)
if manager.write_char != nil{
print("trying")
print(manager.write_char.uuid)
peripheral.writeValue(data!, for: manager.write_char, type: CBCharacteristicWriteType.withoutResponse)
The print statement confirms that this characteristic has the uuid that I defined as being the write characteristic
let WRITE_CHAR = "713D0004-503E-4C75-BA94-3148F18D941E"
I believe this is the correct write characteristic. I have also tried 71230003. On the Launchpad side, I have uploaded the following code:
int incomingByte = 0; // for incoming serial data
void setup() {
// put your setup code here, to run once:
Serial.begin(19200);
Serial1.begin(9600);
pinMode(7, OUTPUT);
}
void loop() {
// put your main code here, to run repeatedly:
//if (Serial1.available()){
// Serial.print("available");
//Read in data
Serial.print(Serial1.available());
Serial.print(" ");
Serial.print(Serial1.read());
Serial.print("\n");
if (Serial1.available() > 0) {
// read the incoming byte:
incomingByte = Serial1.read();
// say what you got:
Serial.print("I received: ");
Serial.println(incomingByte, DEC);
}
}
In the serial monitor, all I receive are 0 from the available check and -1 from the read method both of which signify that no data is being received. Am I transmitting data to the BLE Mini correctly? If so, am I reading it incorrectly? Additionally, is there something I'm supposed to do to tell the BLE Mini to transmit data? Sorry for the long winded question. Thank you so much for the help.