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POways to bind model classes in Objective-C
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  1. POways to bind model classes in Objective-C
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    copied!<p>(I hope someone will correct my terminology if I get it wrong -- I'm still sorting out terms)</p> <p>I have a series of classes in my model. I need to get some data from a url (SatDataGetter) and combine it with a location and date specific calculation (DayCalculater), do some further calculations (DataMixer), some interpretation to make it user-understandable (Advisor), and then present the results in a view. </p> <p>There are issues with setting up the dependencies and making sure that, for instance, the SatDataGetter has valid data <strong>before</strong> it gets called by DataMixer, <strong>before</strong> it gets called by.. you get the idea. Of course, if the location changes, I need to update the whole thing from the bottom up. At minimum I have to get a message to the ViewController and the Advisor to reload their data. </p> <p>The research I've done suggests that NSNotification is one way to go, but I could also try Key-Value Observing. I found some old posts (2009) on KVO, suggesting some possible problems and difficulties with debugging. <a href="http://www.mikeash.com/pyblog/key-value-observing-done-right.html" rel="nofollow">http://www.mikeash.com/pyblog/key-value-observing-done-right.html</a></p> <p>What's the preferred method? What are the issues I should be considering in deciding -- For instance: The SatDataGetter essentially returns a single number. KVO seems like a reasonable way for DataMixer to keep track of what that value is, but I don't think I want all the parent classes to be doing KVO on the dependent variables.</p> <p>When do you choose an NSNotification and when KVO?</p>
 

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