iOS Development — Week 3

That was the end of week 3 — yes I am a bit late posting this… We continued learning Swift, this time it was all about functions, types, closures and advanced swift features.

Closures

• Think of them as “blocks of code that do something
• Differences between closures and functions:

Closures Feature Functions No Names? Yes No Argument labels? Yes No Default parameters? Yes Yes Write Inline? No { (a: Int, b: Int) -> Int in a * b } Different syntax func multiply(a: Int, b: Int) -> Int { a * b }

We have also covered some useful higher order functions:

• forEach - Always runs on all elements, you can pass functions and chain with other methods. Notice that a for loop can use break and continue and where clauses. These do not work with forEach
• map - Goes through all elements of a collection, operate on every single element, and return a new collection with the results.
• compactMap - Only returns collection elements that are not nil
• flatMap - Lets us handle multidimensional arrays. It expects an array as input
• filter - Filters out the elements that meet the required conditions
• reduce - Takes two arguments: an initial value and a closure