Sending data to Core Bluetooth Framework Xcode - iphone

Question

. I am working on an app that uses a core bluetooth framework .App is related to start, lock, unlock doors. I am almost done with the app with the help of examples provided by the Apple. That is Heart Rate Monitor and Temperature Sensor.
I have 2 Questions.
1: Heart Rate Monitor app reads the data from a peripheral while in my case I just have to signal the peripheral that startButton is pressed. So my Question is that whether I have to use writeValueForCharacteristic in discoverCharacteristics method.
2: If so kindly help me with the button code here
- (IBAction) startButtonPressed: (id) sender {
}
- (IBAction) lockDoors: (id) sender {
}
- (IBAction) unLockDoors: (id) sender {
}
Code is given by.
- (void) peripheral:(CBPeripheral *) peripheral didDiscoverServices:(NSError *)error
{
if (error)
{
NSLog(#"Discovered services for %# with error: %#", peripheral.name, [error localizedDescription]);
return;
}
for (CBService * service in peripheral.services)
{
NSLog(#"Service found with UUID: %#", service.UUID);
if([service.UUID isEqual:[CBUUID UUIDWithString:#"1809"]])
{
/* Car Start Service - discover
CAR_START_CHARACTERISTIC_UUID,
LOCK_DOOR_CHARACTERISTIC_UUID,
UNLOCK_DOOR_CHARACTERISTIC_UUID,
TRUNK_CHARACTERISTIC_UUID
ALARM_CHARACTERISTIC_UUID
*/
[peripheralManager discoverCharacteristics:[NSArray arrayWithObjects:[CBUUID UUIDWithString:#"2A1E"], [CBUUID UUIDWithString:#"2A1C"], [CBUUID UUIDWithString:#"2A21"], [CBUUID UUIDWithString:#"2A1F"],[CBUUID UUIDWithString:#"2A1G"],nil] forService:service];
}
else if([service.UUID isEqual:[CBUUID UUIDWithString:#"180A"]])
{
/* Device Information Service - discover manufacture name characteristic */
[peripheralManager discoverCharacteristics:[NSArray arrayWithObject:[CBUUID UUIDWithString:#"2A29"]] forService:service];
}
else if ( [service.UUID isEqual:[CBUUID UUIDWithString:CBUUIDGenericAccessProfileString]] )
{
/* GAP (Generic Access Profile) - discover device name characteristic */
[peripheralManager discoverCharacteristics:[NSArray arrayWithObject:[CBUUID UUIDWithString:CBUUIDDeviceNameString]] forService:service];
}
}
}
- (void) peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error
{
if (error)
{
NSLog(#"Discovered characteristics for %# with error: %#", service.UUID, [error localizedDescription]);
return;
}
if([service.UUID isEqual:[CBUUID UUIDWithString:#"1809"]]) {
for (CBCharacteristic * characteristic in service.characteristics)
{
/* Set Car Start */
if([characteristic.UUID isEqual:[CBUUID UUIDWithString:#"2A1C"]])
{
self.carStartCharacteristic = characteristic;
NSLog(#"Found Car Start Characteristic");
}
/* Set Lock Doors */
if([characteristic.UUID isEqual:[CBUUID UUIDWithString:#"2A1E"]])
{
self.lockDoorsCharacteristic = characteristic;
NSLog(#"Found Lock Doors Characteristic");
}
/* Set Un Lock Doors */
if([characteristic.UUID isEqual:[CBUUID UUIDWithString:#"2A11"]])
{
self.unLockDoorsCharacteristic = characteristic;
NSLog(#"Found UnLock Doors Characteristic");
}
/* Set Trunk Open */
if([characteristic.UUID isEqual:[CBUUID UUIDWithString:#"2A13"]])
{
self.trunkCharacteristic = characteristic;
NSLog(#"Found Trunk Characteristic");
}
/* Set Alarm */
if([characteristic.UUID isEqual:[CBUUID UUIDWithString:#"2A14"]])
{
self.alarmCharacteristic = characteristic;
NSLog(#"Found Alarm Characteristic");
}
}
}if([service.UUID isEqual:[CBUUID UUIDWithString:#"180A"]])
{
for (CBCharacteristic * characteristic in service.characteristics)
{
/* Read manufacturer name */
if([characteristic.UUID isEqual:[CBUUID UUIDWithString:#"2A29"]])
{
[peripheralManager readValueForCharacteristic:characteristic];
NSLog(#"Found a Device Manufacturer Name Characteristic - Read manufacturer name");
}
}
}
if ( [service.UUID isEqual:[CBUUID UUIDWithString:CBUUIDGenericAccessProfileString]] )
{
for (CBCharacteristic *characteristic in service.characteristics)
{
/* Read device name */
if([characteristic.UUID isEqual:[CBUUID UUIDWithString:CBUUIDDeviceNameString]])
{
[peripheralManager readValueForCharacteristic:characteristic];
NSLog(#"Found a Device Name Characteristic - Read device name");
}
}
}
}

Answer 1

You will use both. You will scan (if not previously connected), then discover services, then discover characteristics. Once that is done, you will call writeValueForCharacteristic from your button with whatever value you wish to write.
(IBAction) startButtonPressed: (id) sender {
[peripheral writeValue:yourNSData forCharacteristic:yourCBCharacteristic type:yourWriteType];
}