Regex used in swift to check decimal input - ios

Question

In my application, there are a few textfields with decimal keyboard input. So I need a function to validate the number.
func valueCheck(check: Double) -> Double{
let myRegex = "^(?:|0|[1-9]\\d*)(?:\\.\\d*)?$"
if check != nil && let match = check.rangeOfString(myRegex, options: .RegularExpressionSearch){
return check
}else{
return 0.0
}
}
If the number is not nil or invalid such as a few dots, then return the number. If the number is nil or invalid then return 0.0
I want to use regex but I have no idea how to use it in swift. Any help appreciated.

Answer 1

class func regexMatch(source:String,regexStr:String) -> Bool{
let regex: NSRegularExpression?
do{
try regex = NSRegularExpression(
pattern: regexStr,
options: .CaseInsensitive)
}catch{
return false
}
if let matches = regex?.matchesInString(source,
options: NSMatchingOptions(rawValue: 0),
range: NSMakeRange(0, source.characters.count)) {
return matches.count > 0
} else {
return false
}
}

Answer 2

Swift 2
import Foundation
func valueCheck(d: Double) -> Double {
var result = 0.0
do {
let regex = try NSRegularExpression(pattern: "^(?:|0|[1-9]\\d*)(?:\\.\\d*)?$", options: [])
let results = regex.matchesInString(String(d), options:[], range: NSMakeRange(0, String(d).characters.count))
if results.count > 0 {result = d}
} catch let error as NSError {
print("invalid regex: \(error.localizedDescription)")
}
return result
}
Swift 3
import Foundation
func valueCheck(_ d: Double) -> Double {
var result = 0.0
do {
let regex = try RegularExpression(pattern: "^(?:|0|[1-9]\\d*)(?:\\.\\d*)?$", options: [])
let results = regex.matches(in: String(d), options: [], range: NSMakeRange(0, String(d).characters.count))
if results.count > 0 {result = d}
} catch let error as NSError {
print("invalid regex: \(error.localizedDescription)")
}
return result
}