Converting String to Int with Swift

Question

The application basically calculates acceleration by inputting Initial and final velocity and time and then use a formula to calculate acceleration. However, since the value

Answer 1

I recently got the same issue. Below solution is work for me:

        let strValue = "123"
        let result = (strValue as NSString).integerValue

Answer 2

My solution is to have a general extension for string to int conversion.

extension String {

 // default: it is a number suitable for your project if the string is not an integer

    func toInt(default: Int) -> Int {
        if let result = Int(self) {
            return result
        }
        else {
            return default  
        }
    }

}

Answer 3

//  To convert user input (i.e string) to int for calculation.I did this , and it works.


    let num:Int? = Int(firstTextField.text!);

    let sum:Int = num!-2

    print(sum);

Answer 4

As of swift 3, I have to force my #%@! string & int with a "!" otherwise it just doesn't work.

For example:

let prefs = UserDefaults.standard
var counter: String!
counter = prefs.string(forKey:"counter")
print("counter: \(counter!)")


var counterInt = Int(counter!)
counterInt = counterInt! + 1
print("counterInt: \(counterInt!)")

OUTPUT:
counter: 1
counterInt: 2

Answer 5

In Swift 4:

extension String {            
    var numberValue:NSNumber? {
        let formatter = NumberFormatter()
        formatter.numberStyle = .decimal
        return formatter.number(from: self)
    }
}
let someFloat = "12".numberValue

Answer 6

Swift 3.0

Try this, you don't need to check for any condition I have done everything just use this function. Send anything string, number, float, double ,etc,. you get a number as a value or 0 if it is unable to convert your value

Function:

func getNumber(number: Any?) -> NSNumber {
    guard let statusNumber:NSNumber = number as? NSNumber else
    {
        guard let statString:String = number as? String else
        {
            return 0
        }
        if let myInteger = Int(statString)
        {
            return NSNumber(value:myInteger)
        }
        else{
            return 0
        }
    }
    return statusNumber
}

Usage: Add the above function in code and to convert use let myNumber = getNumber(number: myString) if the myString has a number or string it returns the number else it returns 0

Example 1:

let number:String = "9834"
print("printing number \(getNumber(number: number))")

Output: printing number 9834

Example 2:

let number:Double = 9834
print("printing number \(getNumber(number: number))")

Output: printing number 9834

Example 3:

let number = 9834
print("printing number \(getNumber(number: number))")

Output: printing number 9834