Convert String to CGFloat in Swift

Question

I\'m new to Swift, how can I convert a String to CGFloat?

I tried:

var fl: CGFloat = str as CGFloat
var fl: CGFloat = (CGFloat)str
var fl: CGFloat = CGFl         


        

Answer 1

While the other answers are correct, but the result you see will have trailing decimals.

For example:

let str = "3.141592654"
let foo = CGFloat((str as NSString).floatValue)

Result:

3.14159274101257

To get a proper value back from the string, try the following:

let str : String = "3.141592654"
let secStr : NSString = str as NSString
let flt : CGFloat = CGFloat(secStr.doubleValue)

Result:

3.141592654

Answer 2

Good question. There is not in fact any pure Swift API for converting a string that represents a CGFloat into a CGFloat. The only string-represented number that pure Swift lets you convert to a number is an integer. You'll have to use some other approach from some other library - for example, start with Foundation's NSString or C's (Darwin's) strtod.

Answer 3

If you want a safe way to do this, here is a possibility:

let str = "32.4"
if let n = NSNumberFormatter().numberFromString(str) {
    let f = CGFloat(n)
}

If you change str to "bob", it won't get converted to a float, while most of the other answers will get turned into 0.0.

For Swift 3.0, I'd do something like this:

let str = "32.4"
guard let n = NSNumberFormatter().number(from: str) else { return }
// Use `n` here

In Swift 4, NSNumberFormatter has been renamed to NumberFormatter:

let str = "32.4"
guard let n = NumberFormatter().number(from: str) else { return }

Answer 4

in Swift 3.0

if let n = NumberFormatter().number(from: string) {
  let f = CGFloat(n)
}

or this if you are sure that string meets all requirements

let n = CGFloat(NumberFormatter().number(from: string)!)

Answer 5

You should cast string to double and then cast from double to CGFloat, Let try this:

let fl: CGFloat = CGFloat((str as NSString).doubleValue)

Answer 6

Simple one line solution:

let pi = CGFloat(Double("3.14") ?? 0)