Q:

Updating UI from IOS library

Could somebody give me guidance/starting point on how I would update a UI Text Label in an IOS app from a library. 
I have temperature data being received from  a BT module in a library connected to my app.  I want to send that Integer data to my app and update the UI Text label. 
NOTE: I have full access to the library.   
Any help is appreciated

A:

I think what you are asking for is a way to provide feedback to an application from your Cocoa static library. 
I would suggest that you have a look at the NSNotificationCenter class.  For example, say that you have a class BTThermometer that, upon the reception of a new measurement calls:
 [[NSNotificationCenter defaultCenter] postNotificationName:@"com.my. BTThermometer. NewValue" object:self];

Then, in you application, you could do something like:
[[NSNotificationCenter defaultCenter] addObserverForName:@"com.my. BTThermometer. NewValue" object:self queue:nil usingBlock:^(NSNotification* n) {
    dispatch_async(dispatch_get_main_queue(), ^{
        someLabel.text = ((BTThermometer*)n.object).temperatureValue;
    }
}];

This is a standard mechanism in iOS to decouple your application from the internal workings of your library.  The only coupling is the name itself, and of course it is usually a good idea to use a constant (e.g. #define kMyTemperatureEvent @"com.my. BTThermometer. NewValue) so that the compiler catches any typos.