Can you evaluate a string in Swift?

swift string expression-evaluation
Krncy picture Krncy · Mar 11, 2015 · Viewed 7.1k times · Source

I have a variable and I have a function stored in it as a string:

var x = "func myFunction(y :Int) {println(y)}"

Is there a way to evaluate the string and run the function?

Answer

AstroCB picture AstroCB · Mar 11, 2015

No.

There is no equivalent of eval() in JavaScript or ScriptEngine in Java for Swift.

A common use for string evaluation is mathematical expressions; if you want to evaluate these, you can use NSExpression.valueWithExpression(format: String):

let stringWithMathematicalOperation: String = "5*5" // Example
let exp: NSExpression = NSExpression(format: stringWithMathematicalOperation)
let result: Double = exp.expressionValue(with:nil, context: nil) as! Double // 25.0

Related questions

Convert Int to String in Swift

I'm trying to work out how to cast an Int into a String in Swift. I figure out a workaround, using NSNumber but I'd love to figure out how to do it all in Swift. let x : Int = 45 let xNSNumber = …

Read More
Split a String into an array in Swift?

Say I have a string here: var fullName: String = "First Last" I want to split the string base on white space and assign the values to their respective variables var fullNameArr = // something like: fullName.explode(" ") var firstName: String = fullNameArr[0] var …

Read More
Get the length of a String

How do you get the length of a String? For example, I have a variable defined like: var test1: String = "Scott" However, I can't seem to find a length method on the string.

Read More