VariablesInSwift

import Cocoa

/* To declare a variable in Swift, simply assign something to it, like below: */

var str = "Hello, playground"

/* As you can see, there is no explicit type declared.  This is because type inference will notice that the variable 'str' is being assigned a string and the compiler will infer that str is of type 'String' */

/* You can declare a Type explicitly using a 'Type Annotation' like this */

var strVar: String = "Something"

/* The colon can be read as `of type` so this code would read "variable strVar of type String equals "Something" */

/* It is rare that you will need type annotations in practice if you provide an initial value for a variable.  This is because the compiler will be able to infer the type (as discussed earlier).  If however, you are declaring a variable before defining it, it might be useful to declare it ahead of time.  Consider this */

var someMessage: String

/* At this point, the compiler knows that someMessage will be a string even before it has been assigned.  If we try to assign a value other than a string, it will show an error. */


// OK
someMessage = "Hello!"
// Error
// someMessage = 15