Lazy Closures Using Swift
Delay that heavyweight work
I’ve previously written an article about Lazy Variables but feel that it doesn’t go into enough detail about closures to set up a property and I’m not that happy about the examples used.
Time has passed. I’m now a better coder. Can I write a better article?
Let’s get into it.
Terminology
Closure: A self-contained block of functionality that can be passed around
lazy: A keyword indicating that it is a property whose initial value isn’t calculated until the first time it’s used. Must be declared as a variable (with the var keyword)
Using A Closure To Initialize A Property
Why
When you want to set up a property but the initial value is relatively expensive to create, you might want to ensure you do it *just once* and *only when necessary*.
We can do that by **using a closure*.
The Example
If we create some code to read a json file and output a String if the file is successfully read. This isn’t necessary production-ready code for reading a file (hey, it works) but is a good example for this particular article.
