https://homeostasis.scs.carleton.ca/wiki/index.php?action=history&feed=atom&title=Mobile_App_Development_2021W_Lecture_5 2026-04-26T13:50:57Z Revision history for this page on the wiki MediaWiki 1.42.1 https://homeostasis.scs.carleton.ca/wiki/index.php?title=Mobile_App_Development_2021W_Lecture_5&diff=22859&oldid=prev 2021-01-25T21:33:47Z

<p>Created page with &quot;==Video== Video from the lecture given on January 25, 2021 [https://homeostasis.scs.carleton.ca/~soma/mad-2021w/lectures/comp1601-2021w-lec05-20210125.m4v is now available]....&quot;</p> <p><b>New page</b></p><div>==Video==<br /> <br /> Video from the lecture given on January 25, 2021 [https://homeostasis.scs.carleton.ca/~soma/mad-2021w/lectures/comp1601-2021w-lec05-20210125.m4v is now available].<br /> <br /> ==Notes==<br /> <br /> &lt;pre&gt;<br /> Lecture 5<br /> ---------<br /> Lecture topics<br /> Swift functions &amp; closures<br /> Swift dictionaries &amp; arrays<br /> Writing simple command line synchronous interface in Swift<br /> Declaring custom views in SwiftUI<br /> SwiftUI @State and @Binding<br /> SwiftUI ForEach<br /> <br /> Key ideas<br /> - functions can be passed around as data<br /> - functions without names are called closures, in other languages lambda is the term<br /> (lambda comes from lamda calculus, worth looking up)<br /> <br /> Why closure?<br /> - encapsulates the lexical scope of where the function is declared<br /> - regular languages do (mostly) lexical scoping)<br /> - variables &amp; other symbols are valid or not depending on where they are found<br /> in the source code<br /> - lexical scoping really only comes up when you have functions defined inside of<br /> other things (like struct, class, function)<br /> - closures &quot;remember&quot; where they were declared, can see those symbols<br /> <br /> closures are typically used for callbacks<br /> - you pass a function in as an argument, it will get called later by someone else<br /> at some time, you don&#039;t know when or in what context<br /> <br /> Event driven programming tends to lead to closures in some form<br /> - because you have to specify what happens in response to events<br /> &lt;/pre&gt;</div>

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