The error message is quite clear. You cannot declare an extension inside of anything – inside a class declaration, inside a struct declaration, etc. It must be outside of everything, at the top level of the containing file. There must be no curly braces around it. You have not shown the context in which you are declaring this extension, but clearly there are curly … Read more
Tuple A tuple is a grouping of unnamed, ordered values. Each value in a tuple does not need to be the same type. Array An array is mutable collection. They are very efficient to create, but must always be a single type.
All of the following examples use Swift 4 Strings got a pretty big overhaul in Swift 4. When you get some substring from a String now, you get a Substring type back rather than a String. Why is this? Strings are value types in Swift. That means if you use one String to make a new one, then … Read more
It’s been a few weeks since I posted this, but I believe what Aaron Brager said is true. While Protocol-Oriented-Programming is rather new in itself, the idea of protocols has been present in Objective-C for a long time, they are in Swift, and they have their variants in languages such as Java. Due to the … Read more
I faced the same error in a different context, in XCode 12.0.1 too. It might not be related, but I suspect its an issue with accessing the run loop of the main thread. I was just trying out some introductory code I found online, and faced the same issue, so this is a bug, rather than a … Read more
Background: What’s an Optional? In Swift, Optional<Wrapped> is an option type: it can contain any value from the original (“Wrapped”) type, or no value at all (the special value nil). An optional value must be unwrapped before it can be used. Optional is a generic type, which means that Optional<Int> and Optional<String> are distinct types — the type inside <> is called the Wrapped type. Under the hood, … Read more
I am getting a ‘Type of expression is ambiguous without more context ‘ on this part of code from a project I am trying to upgrade to latest Swift version. I can’t seem to figure it out. I tried different things but can’t get it to work. The problem is on the syntax of this line … Read more