1、In Swift,you can optionally use underscores to make larger numbers more human-readable. The quantity and placement of the underscores is up to you.
var variableNumber: Int = 1_000_000
var integer: Int = 100 var decimal: Double = 12.5 integer = decimal // wrong integer = Int(decimal) // right
3、Here is how to access the data inside the tuple:
let coordinates: (Int,Int) = (2,3) let x: Int = coordinates.0 let y: Int = coordinates.1
You can reference each item in the tuple by its position in the tuple,starting with zero. Swift allows you to name the individual parts of a tuple,so you to be explicit about what each part represents. For example:
let coordinatesNamed: (x: Int,y: Int) = (2,3) let x: Int = coordinatesNamed.x let y: Int = coordinatesNamed.y
If you want to access multiple parts of the tuple at the same time,you can also use a shorthand Syntax to make it easier:
let coordinates3D: (x: Int,y: Int,z: Int) = (2,3,1) let (x,y,z) = coordinates3D
The code is equivalent to the following:
let coordinates3D: (x: Int,1) let x = coordinates3D.x let y = coordinates3D.y let z = coordinates3D.z
If you want to ignore a certain element of the tuple,you can replace the corresponding part of the declaration with an underscore.
let (x,_) = coordinates3D
This line of code only declaresxandy. The_is special and simply means you are ignoring this part for now. You'll find that you can use the underscore throughout Swift to ignore a value.
4、Sometimes it's useful to check the inferred type of a variable or constant. You can do this in a playground by holding down theOptionkey and clicking on the variable or constant's name.
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