Swift language-constants, variables, type assignments

constants: constants cannot be assigned in scope and will not change, read-only, and each constant must have a unique name and memory space; Keyword: let

variable: the variable can be changed in the scope of the action, its value can be altered, readable writable can be overwritten, each constant must have a unique name and memory space; Keyword: var

Variable type assignment:

var str = "Hello" var s:string = "World" var i:int = 100

Var world:string = "Wojiaoadong"

Swift language-constants, variables, type assignments