bluetooth-lowenergy

I'm currently working on an app that I want for my app to detect a beacon in background mode just when it gets close to it(Immediate). Based on articles that I've read it cannot be done with didEnterRegion and I should use ranging while it's running in the background mode(Location Update). is there any solution that directly reduces the didEnterRegion threshold? or Should I use the other method? and if that's the case does it work like didEnterRegion but with a limited range of RSSI? does it work when my phone entered the region and it's locked and the screen is off? Monitoring APIs give you

We are working on iOS application and in which we need to pass the RGB signal to the BLE device and based on RGB code the device LED will glow. We are doing the connection using CBCentralManager for the CBPeripheral object of Bluetooth Framework in iOS app. We are setting the characteristic and descriptor UUID but still we are not able to send the signal on the BLE device. Here is the code we are using to pass RGB data in hex bytes format. - (void)centralManager:(CBCentralManager )central didConnectPeripheral:(CBPeripheral )peripheral { NSLog(@"connect peripheral"); unsigned char bytes[] = {