Monitor changes and update the widget in real time.#335
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Use KVO to watch the UserDefaults object and update the view as appropriate.
| self, | ||
| forKeyPath: defaults.statusExtensionContextObservableKey, | ||
| options: [.new, .initial], | ||
| context: nil) |
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It's important to use a context here. Example:
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Will do. The purpose of the context member was pretty opaque to me. I'm assuming it's some kind of semaphore that lets you know that the notification is relevant to this particular instance.
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Is it legit to use the context variable (defined as var context: StatusExtensionContext?) for this purpose? It's convenient. If not, I'll create a new var.
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I wouldn't, foremost because it's convoluting the term "context" for future readers, but secondly because you're looking for a unique pointer value here, and it should feel safer to instead use one containing a simple integer value that never changes.
| defaults.addObserver( | ||
| self, | ||
| forKeyPath: defaults.statusExtensionContextObservableKey, | ||
| options: [.new, .initial], |
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If you aren't using the change dict in the observer than you should leave these blank.
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can you elaborate on that? Not sure what you mean by using the change dict in the observer.
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passing the .new key here is so it is included in the observeValue call below. .initial means the observer is called right away, which isn't what you want.
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| override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) { | ||
| update() |
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Always check the context. If it doesn't match, then you must call super.
| subtitleLabel.textColor = UIColor.secondaryLabelColor | ||
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| override func viewWillAppear(_ animated: Bool) { |
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this can be called multiple times, and disappear can as well. These two aren't always balanced in the case of an interactive transition.
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ok, that's good to know. I'll move these to viewDidLoad() and deinit, following the pattern in PredictionTableViewController
1. call addObserver() in viewDidLoad() 2. call removeObserver() in deinit 3. don't specify options in addObserver() 4. provide a context to the observer code
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Ok - I think I covered all the issues you raised. Thanks for the guidance! I'm not sure how to properly test this in the simulator, because when I go to the lock screen, the Loop app isn't updating so I don't see any changes. Any thoughts on how to test it in the simulator? If not, I'll deploy it to my phone and just observe it for 5-10 minutes :-) |
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| override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) { | ||
| if context != &self.context { |
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Early returns should really only exist in guard statements.
(see Carthage/Carthage#3019 for details)
3 participants
Use KVO to watch the UserDefaults object and update the view as
appropriate. This is a first pass at resolving #320.