Before I can describe the use cases for Implicitly Unwrapped Optionals, you should already understand what Optionals and Implicitly Unwrapped Optionals are in Swift. If you do not, I recommend you first read my article on optionals When To Use An Implicitly Unwrapped Optional There are two main reasons that one would create an Implicitly … Read more
Swift 4.2+ Swift 4.2 shipped with Xcode 10 introduces new easy-to-use random functions for many data types. You can call the random() method on numeric types. let randomInt = Int.random(in: 0..<6) let randomDouble = Double.random(in: 2.71828…3.14159) let randomBool = Bool.random()
You can use Swift’s round function to accomplish this. To round a Double with 3 digits precision, first multiply it by 1000, round it and divide the rounded result by 1000: let x = 1.23556789 let y = Double(round(1000 * x) / 1000) print(y) /// 1.236 Unlike any kind of printf(…) or String(format: …) solutions, … Read more
What does it mean to “unwrap the instance”? Why is it necessary? As far as I can work out (this is very new to me, too)… The term “wrapped” implies we should think of an Optional variable as a present, wrapped in shiny paper, which might (sadly!) be empty. When “wrapped”, the value of an … Read more
According to the very popular WWDC 2015 talk Protocol Oriented Programming in Swift (video, transcript), Swift provides a number of features that make structs better than classes in many circumstances. Structs are preferable if they are relatively small and copiable because copying is way safer than having multiple references to the same instance as happens … Read more
A few differences: print vs println: The print function prints messages in the Xcode console when debugging apps. The println is a variation of this that was removed in Swift 2 and is not used any more. If you see old code that is using println, you can now safely replace it with print. Back … Read more
This answer has been updated for Swift 4 & 5. If you’re still using Swift 1, 2 or 3 see the revision history. You have a couple of options. You can do as @jaumard suggested and use replacingOccurrences() let aString = “This is my string” let newString = aString.replacingOccurrences(of: ” “, with: “+”, options: .literal, … Read more
This has to do with how the String type works in Swift, and how the contains(_:) method works. The ‘👩👩👧👦 ‘ is what’s known as an emoji sequence, which is rendered as one visible character in a string. The sequence is made up of Character objects, and at the same time it is made up … Read more
This post is relevant here https://www.swift-studies.com/blog/2014/6/10/enumerating-enums-in-swift Essentially the proposed solution is enum ProductCategory : String { case Washers = “washers”, Dryers = “dryers”, Toasters = “toasters” static let allValues = [Washers, Dryers, Toasters] } for category in ProductCategory.allValues{ //Do something }
tl;dr: Use the class constant approach if you are using Swift 1.2 or above and the nested struct approach if you need to support earlier versions. From my experience with Swift there are three approaches to implement the Singleton pattern that support lazy initialization and thread safety. Class constant class Singleton { static let sharedInstance … Read more