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iOS Intermediate Swift 2 Extensions and Protocols Extending a Native Type

checking int from given String

how to check an Int from given String and how to return nil from expected return Int

types.swift
// Enter your code below
extension String {
 func add(tambah: Int) -> Int {
    if self == self.toInt() {
        return self + tambah
    } else { return nil }
 }

}

"1".add(2)

2 Answers

extension String {

    func add(value: Int) -> Int? {

        guard let intVal = Int(self) else {
            return nil
        }

        return intVal + value
    }
}

omg im totally forget about optional thanks