Writing functions
Functions let us re-use code, which means we can write a function to do something interesting then run that function from lots of places. Repeating code is generally a bad idea, and functions help us avoid doing that.
To start with, we’re going to write a function that prints help information for users of our app. We might need this anywhere in our app, so having it as a function is a good idea.
Swift functions start with the func keyword, then your function name, then open and close parentheses. All the body of your function – the code that should be run when the function is requested – is placed inside braces.
Let’s write the printHelp() function now:
func printHelp() {
let message = """
Welcome to MyApp!
Run this app inside a directory of images and
MyApp will resize them all into thumbnails
"""
print(message)
}We can now run that using printHelp() by itself:
printHelp()Running a function is often referred to as calling a function.
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