https://stackoverflow.com/questions/23089472
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RussianWhy property's value bound to NSDatePicker does not always reflect what control shows?
In Model-View-Controller pattern, your NSDatePicker is the view, your ViewController is the controller, and the NSDate property is the model.
You bind a view to a model via a controller. Not the other way round.
When you bind a view to a model via a controller, the view will start reflecting the model. If you interact with the view (e.g., change the date), the change will be applied to the model.
Initial value. Date picker shows it's initial date (set in IB) but bound property returns nil (if user does not interact with picker).
NSDatePicker shows whatever default value, because the model is not providing an NSDate object. NSDatePicker should NOT change the model without user interaction.
Min value changes date in picker, but bound property still returns old value (the value user had set before min value was set).
NSDatePicker just shows a default value within the range of acceptable values, because the model is not providing an NSDate object.
What is the reason to use bindings over target/action if it does not support such fundamental behaviour?
Target/action is just part of what bindings does automatically. Without bindings, you would create an action method in your controller (the target) to handle user interaction (e.g., user changing the date). In the action method, you would then change the model object. Also, on loading the view, you would sync the view to what you have in your model. Bindings eliminates a lot of this kind of code.
