Learning Swift™ Programming

The Closure Syntax

You can rewrite that last alphabetical function to be an inline closure. It would look like this:

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var alphabetical = {(s1:String, s2:String) -> Bool in s1 < s2}

You remove the func keyword and the name of the function. You put the whole thing in some curly brackets and put the actual content after the word in and remove the keyword return. The closure knows that it should return stuff. The closure by itself doesn’t do much. You need to either save it to a variable or pass it directly into the sort function. Notice how it still matches the signature of the previous function you used. It takes two Strings and returns a Boolean. Now you can pass this into the sort function:

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