Advice please on where to look for online tutorial/help. Rather than an email, Twitter, etc alert I just want a simple app that gives an audible alert when triggered by an output from a sensor/imp combo . For example temp on sensor drops below 20c , app “dings” . I would quite like to write it from scratch and have no idea where to start , so I’m happy to just use something generic.
Maybe these 3rd party API-based realtime systems, which the IMP agent can “talk” to, will be a good place to get started.
Both have tutorials / ready-made libraries to work from to create apps.
For iOS development, you’ll need Apple’s Xcode application, which you can get from the App Store. If you are new to iOS and/or Objective-C programming, I’d recommend you get Beginning iOS Development, which is a great step-by-step guide to the iOS SDK. It’s currently only up to iOS 7, but that’s sufficient for the kind of iOS 8 app you have in mind.
Remember that iDevices aren’t servers, so your app will have to query your agent regularly to get the current sensor reading, and then use that to determine whether to ping or not.
You can see how this might work in my (now rather old) iOS app, Impicity. You can look at the source code once you’ve got a handle on programming iOS from the book I mentioned above, or another source. Once you get the basic structure of an iOS app under your belt, and get a handle on implementing the various UI features, you can start exploring the iOS API directly: just Google the class name, eg. NSString, to get the Apple docs.