Add a way to cancel all pending commands for a peripheral

In our app, once the user "pairs" to a peripheral, we use a connectionDelegate to re-issue a characteristic write as soon as it disconnects, which works great. Later, in the UI the user can also manually forget a peripheral, and at this point I was calling RZBPeripheral.cancelConnection.

However, I noticed that if I had that pending write command for that peripheral, the library would pro-actively retry the connection command, which would leave a dangling connection request for a device that the app has no interest in anymore, and that was causing some issues. I searched for a way to cancel all outstanding commands for a peripheral but didn't find anything, so I ended up hacking that feature into RZBPeripheral with an extension:

@implementation RZBPeripheral (Cancellation)

- (RZBCommandDispatch *)hs_dispatch {
    SEL selector = NSSelectorFromString(@"dispatch");
    IMP imp = [self methodForSelector:selector];
    RZBCommandDispatch* (*func)(id, SEL) = (void *)imp;
    return func(self, selector);
}

- (void)hs_cancelAllCommands {
    NSArray *commands = [self.hs_dispatch commandsOfClass:nil
                                 matchingUUIDPath:RZBUUIDP(self.identifier)
                                       isExecuted:YES];

    NSError *error = [NSError errorWithDomain:[NSString stringWithFormat:@"%@-hs", RZBluetoothErrorDomain]
                                         code:1
                                     userInfo:@{NSLocalizedDescriptionKey: @"The operation has been manually cancelled by the user"}];

    for (RZBCommand *command in commands) {
        [self.hs_dispatch completeCommand:command withObject:nil error:error];
    }
}

@end

I feel like this is a useful feature to add to the library, do you agree? If so, what do you think of this solution? If you think this approach is fine I can submit a PR with this change.

Rightpoint / RZBluetooth

Add a way to cancel all pending commands for a peripheral #78