https://homeostasis.scs.carleton.ca/wiki/index.php?action=history&feed=atom&title=Mobile_App_Development_2022W_Lecture_4 2026-04-06T01:53:00Z 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_4&diff=23696&oldid=prev 2022-01-21T20:29:45Z

<p><span dir="auto"><span class="autocomment">Video</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 20:29, 21 January 2022</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l5">Line 5:</td> <td colspan="2" class="diff-lineno">Line 5:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>* [https://homeostasis.scs.carleton.ca/~soma/mad-2022w/lectures/comp1601-2022w-lec04-20220121.cc.vtt auto-generated captions]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>* [https://homeostasis.scs.carleton.ca/~soma/mad-2022w/lectures/comp1601-2022w-lec04-20220121.cc.vtt auto-generated captions]</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>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.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>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.</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">(Video links don't work now, will be fixed a bit later today.)</del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Notes==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Notes==</div></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Mobile_App_Development_2022W_Lecture_4&diff=23695&oldid=prev 2022-01-21T18:02:16Z

<p>Created page with &quot;==Video== Video from the lecture given on January 21, 2022 is now available: * [https://homeostasis.scs.carleton.ca/~soma/mad-2022w/lectures/comp1601-2022w-lec04-20220121.m4v...&quot;</p> <p><b>New page</b></p><div>==Video==<br /> <br /> Video from the lecture given on January 21, 2022 is now available:<br /> * [https://homeostasis.scs.carleton.ca/~soma/mad-2022w/lectures/comp1601-2022w-lec04-20220121.m4v video]<br /> * [https://homeostasis.scs.carleton.ca/~soma/mad-2022w/lectures/comp1601-2022w-lec04-20220121.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 /> (Video links don&#039;t work now, will be fixed a bit later today.)<br /> <br /> ==Notes==<br /> &lt;pre&gt;<br /> Lecture 4<br /> ---------<br /> <br /> Remember that in swift, references by default always have a value<br /> - they won&#039;t have &quot;nil&quot;<br /> <br /> But sometimes operations won&#039;t return a valid value<br /> - i.e., looking something up in a dictionary, getting user input<br /> <br /> So swift forces us to handle the case of it being nil before it allows<br /> us to use the data<br /> <br /> The idea of optional types and unwrapping optional types is all about changing runtime errors (oops, the value is nil when it should have been something valid) into a compile time error.<br /> <br /> Notice in Swift we don&#039;t normally deal with &quot;exceptions&quot;<br /> - errors are handled where they are generated generally<br /> <br /> Any view can have @State variables<br /> <br /> We use @Binding to share variables between views<br /> - one declares it with @State<br /> - the other references it using @Binding<br /> - The declaring one must then include the @Binding one, connecting<br /> the variables as part of the inclusion.<br /> &lt;/pre&gt;</div>

Soma