Swift number formatting, rounding, and validation extensions

NumberFormatting.swift

print("Pi Time: \(3.14.f(3))")

let myNumber = 4.20 / 6.9
print("the answer is \(myNumber.f(5))")

NumericExtensions.swift

import Foundation

extension Double {
    func roundTo(_ places: Int) -> Double {
        let divisor = pow(10.0, Double(places))
        return (self * divisor).rounded() / divisor
    }
    
    var isValidInt: Bool {
        if self >= Double(Int.max) || self < Double(Int.min) || self.isNaN || self.isInfinite {
            return false
        }
        return true
    }
    
    func f(_ numberOfFractionalDigits: Int) -> String {
        self.formatted(.number.precision(.fractionLength(numberOfFractionalDigits)))
    }
}

extension Float {
    var isValidInt: Bool {
        if self >= Float(Int.max) || self < Float(Int.min) || self.isNaN || self.isInfinite {
            return false
        }
        return true
    }
    
    func f(_ numberOfFractionalDigits: Int) -> String {
        self.formatted(.number.precision(.fractionLength(numberOfFractionalDigits)))
    }
}