Thank you all for the opinions. I left the code as-is in terms of binding, but changed my rate calculations to use a weighted running average. After doing so, the estimated seconds tick by one at a time for the most part, and the rate is more constant. This is a tool for me and some co-workers, so at this point, it is good enough. But the ideas are sound and if it bothers me enough, I may decouple the UI from the model by not using bindings at some point and use a timer based approach.
On Sat, Jan 14, 2012 at 10:37 AM, Kyle Sluder <kyle.slu...@gmail.com> wrote: > On Jan 14, 2012, at 2:53 AM, Marcel Weiher <marcel.wei...@gmail.com> wrote: > >> Hi Andrew, >> >> On Jan 13, 2012, at 6:57 , Andrew wrote: >> >>> The result of this is that the UI updates really frequently and the >>> estimated time to complete and the download rate jump around a lot. I >>> would love it if I could tell cocoa to only update the UI once per >>> second instead of immediately when the property key changes. >> >> You shouldn't push updates to the UI, the UI should query the model, and it >> should do it at "human speed", not at whatever speed the machine can manage >> to change the state. There are a bunch of reasons for this, not least is >> that UI updating is fairly heavyweight and you can actually impact your >> performance (significantly, in some cases). > > Be careful here. This is good advice in this particular circumstance, but in > general pushing values to the UI is good and common design. The UI will > register as a KVO observer, or as an NSNotification observer, or perhaps the > controller will just call -setObjectValue: directly. > > Breaking this pattern should be a conscious decision. For example, you don't > push a value to cell-based NSTableViews; you tell the table view it needs to > ask you for the values at certain indexes. This is because cell-based table > views are an optimization that avoids keeping tons of view objects around. > > But view-based table views behave just like any other view: you push updates > directly to the controls contained within your table cell view. > > In Andrew's case, it's clear that he should deviate from the norm, and the UI > should be in charge of asking for the latest value at a rate that makes > sense, probably controlled by an NSTimer. > > --Kyle Sluder _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
