Network Programming in .NET

Yes, I just got an apple watch, and the first thing I want to do with it, is to learn to program on it. so, apart from a simple “Hello World” app. I wanted to create a very simple companion app for a bitcoin app (https://itunes.apple.com/gb/app/get-bitcoin/id1072062149?mt=8)  – which just looks up the BTC / USD exchange rate and shows it on the watch.

So, here’s the code;

@interface InterfaceController()

@property (unsafe_unretained, nonatomic) IBOutlet WKInterfaceLabel *lblHello;

@end

@implementation InterfaceController

– (void)awakeWithContext:(id)context {

    [super awakeWithContext:context];

    // Configure interface objects here.

     [self.lblHello setText:@”Loading…”];

    // make request to https://blockchain.info/tobtc?currency=USD&value=1

    NSURL *url = [NSURL URLWithString:@”https://blockchain.info/tobtc?currency=USD&value=1″];

    NSError* error;

    NSString *content = [NSString stringWithContentsOfURL:url encoding:NSASCIIStringEncoding error:&error];

    // Check for network errors

    if (error)

    {

       [self.lblHello setText:@”Network error”];

       return;

    }

    // Get reciprocal

    float fRate = [content floatValue];

    float fReciprocal = 1 / fRate;

    

    NSString *str = [NSString stringWithFormat:@”$%.2lf”, fReciprocal];

    

    [self.lblHello setText:str];

}