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What's the correct way to declare an empty tuple?
var myArr : [String] = []
var myTuple: (key: String, val: Int) = () ?Is there a correct way to achieve this?
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In order to create a tuple, first declare a tuple in Swift, we declare a constant or a variable in our code and type the data directly into the circular brackets separated with a comma. Below is the basic structure of a tuple where data1, data2, data3,……,dataN can all be of the same or distinct data type.
The reason that tuples cannot be used as keys (or specifically, are not hashable ) is because they are not strictly immutable. If you define it using let , it is immutable, but if you define it using var , it is not.
Types in Swift fall into one of two categories: first, “value types”, where each instance keeps a unique copy of its data, usually defined as a struct, enum, or tuple. The second, “reference types”, where instances share a single copy of the data, and the type is usually defined as a class.
There's no such thing as an "unfilled" tuple value. In other words you don't create an empty tuple and then add values to it later. It's important to remember that tuples aren't collections like Array or Dictionary. Tuples are structured types. For example, you can't iterate through a tuple with a for loop. In your example, myTuple is a single value that happens to contain a String and an Int.
A tuple is like an on-demand unnamed structure, such as the following struct but if it were possible for it to be unnamed:
struct MyStruct {
let key: String
let val: Int
}
If you want to model a missing tuple value, you should make the type of the entire tuple optional. For example:
var myTuple: (key: String, val: Int)? = nil
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