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Welcome to the Collection Swift session.

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We're going to ask you
to do some reading about

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the Swift collection types.

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It's a really important topic, but we
think you'll find it's pretty pleasant.

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There are only two collection types,
arrays and dictionaries.

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They're both really clean,
really easy to use.

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Let's start with the dictionary.

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There are two small wrinkles that we
want to discuss before we read the books

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chapter on collections.

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Two short side topics.

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The first is the topic of tuples.

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The chapter that you'll read
discusses this loop for

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iterating through a dictionary and
printing out all the keys and values.

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Notice that for each iteration,
we'll handle two values in parenthesis.

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We call these tuples.

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They're an interesting feature in Swift.

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Right now, UIKit doesn't make
a lot of use of tuples, but

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reading up on them will help as
you read the collections chapter.

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The second side topic worth
reading up on is how to deal with

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NSDictionaries and NSArrays.

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These are the objective C collections
classes used in UIKit libraries.

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In this example, I've created a UIView
and I'm asking it for its subviews.

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We can ask for the count of the subviews
and it's zero as we'd expect for

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a brand new view.

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But if you look at the documentation for
the UIView class,

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you'll see that it's an NSArray.

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Since all of UIKit is written in
objective C, it pays off to take a quick

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look at how Swift works with
NSArrays and dictionaries.

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You'll find that this kind of
thing comes up a lot in UIKit.

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We think you'll be pleased to see that
the objective C collections integrate

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fairly seamlessly into Swift.

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So take a look at the reading list.

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It asks you to read
a section on tuples first,

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then a chapter on Swift collections.

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And finally, a small section on using
NSArrays and NSDictionaries in Swift.

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As always,

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make sure to take full advantage of the
discussion forums as questions come up.