https://homeostasis.scs.carleton.ca/wiki/index.php?action=history&feed=atom&title=Mobile_App_Development_2022W_Lecture_10 2026-04-06T06:18:27Z Revision history for this page on the wiki MediaWiki 1.42.1 https://homeostasis.scs.carleton.ca/wiki/index.php?title=Mobile_App_Development_2022W_Lecture_10&diff=23827&oldid=prev 2022-02-12T05:57:43Z

<p>Created page with &quot;==Video== Video from the lecture given on February 11, 2022 is now available: * [https://homeostasis.scs.carleton.ca/~soma/mad-2022w/lectures/comp1601-2022w-lec10-20220211.m4...&quot;</p> <p><b>New page</b></p><div>==Video==<br /> <br /> Video from the lecture given on February 11, 2022 is now available:<br /> * [https://homeostasis.scs.carleton.ca/~soma/mad-2022w/lectures/comp1601-2022w-lec10-20220211.m4v video]<br /> * [https://homeostasis.scs.carleton.ca/~soma/mad-2022w/lectures/comp1601-2022w-lec10-20220211.cc.vtt auto-generated captions]<br /> Video is also available through Brightspace (Resources-&gt;Zoom Meetings (Recordings, etc.)-&gt;Cloud Recordings tab). Note that here you&#039;ll also see chat messages.<br /> <br /> ==Notes==<br /> <br /> &lt;pre&gt;<br /> Lecture 10<br /> ----------<br /> <br /> introduce Assignment 2<br /> continue with Tutorial 5<br /> <br /> Go ahead and download android studio before next Wednesday<br /> - give it time to run and update itself<br /> <br /> Plain text files can have different line endings<br /> - CR, \r &lt;--- old MacOS (like, really old)<br /> - LF, \n &lt;--- Linux, UNIX, modern macOS<br /> - CR+LF, \r\n &lt;--- windows<br /> <br /> When you have a controller in Storyboard that can send events, those events are received by functions that are marked with &quot;@IBAction&quot;<br /> - you then have to connect the function to the correct storyboard outlet<br /> for the sent event<br /> <br /> AnalysisResult view in textanalyzer-2 corresponds to<br /> updateAnalysis in textanalyzer-3.<br /> - updateAnalysis is called in three places<br /> - when the first view is displayed<br /> - when the user types anything into the input field<br /> - when a menu item is selected<br /> - but, when is AnalysisResult called?<br /> - it is run whenever it needs to be, automatically<br /> - it will run when Contentview is put on the screen<br /> (because AnalysisResult is included), and it will run<br /> whenever mode and userInput change<br /> - i.e., when a menu item is selected and when a user types<br /> - but these calls are implicit, not explicit, we don&#039;t<br /> have to put them in manually, they just happen<br /> <br /> Remember, in SwiftUI, when a @State variable changes, any views dependent on those state variables are automatically updated (i.e., their code is re-run)<br /> <br /> When you have to do updates manually, it is very easy to skip or to do the wrong ones<br /> - then your interface is stale, doesn&#039;t reflect the underlying app state<br /> - leads to lots of bugs<br /> <br /> That&#039;s why the modern way is to do things more declaratively<br /> - tell the system what the screen looks like based on data<br /> - the framework figures out when the screen needs to be updated based<br /> on changes to designated data<br /> <br /> @State variables are the actual &quot;state&quot;<br /> @Binding variables are references to @State variables<br /> - essentially pointers/call by reference<br /> <br /> @State variables are really objects under the hood which do extra work whenever the object&#039;s properties are read from or written to<br /> - the set&#039;s and get&#039;s are overridden with extra functionality<br /> &lt;/pre&gt;</div>

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