How to convert a String (numeric) in a Int array in Swift
@rintaro's answer is correct, but I just wanted to add that you can use reduce
to weed out any characters that can't be converted to an Int
, and even display a warning message if that happens:
let str = "123456789"
let intArray = reduce(str, [Int]()) { (var array: [Int], char: Character) -> [Int] in
if let i = String(char).toInt() {
array.append(i)
} else {
println("Warning: could not convert character \(char) to an integer")
}
return array
}
The advantages are:
- if
intArray
contains zeros you will know that there was a0
instr
, and not some other character that turned into a zero - you will get told if there is a non-
Int
character that is possibly screwing things up.
Swift 3
Int array to String
let arjun = [1,32,45,5]
print(self.get_numbers(array: arjun))
func get_numbers(array:[Int]) -> String {
let stringArray = array.flatMap { String(describing: $0) }
return stringArray.joined(separator: ",")
String to Int Array
let arjun = "1,32,45,5"
print(self.get_numbers(stringtext: arjun))
func get_numbers(stringtext:String) -> [Int] {
let StringRecordedArr = stringtext.components(separatedBy: ",")
return StringRecordedArr.map { Int($0)!}
}
You can use flatMap to convert the characters into a string and coerce the character strings into an integer:
Swift 2 or 3
let string = "123456789"
let digits = string.characters.flatMap{Int(String($0))}
print(digits) // [1, 2, 3, 4, 5, 6, 7, 8, 9]"
Swift 4
let string = "123456789"
let digits = string.flatMap{Int(String($0))}
print(digits) // [1, 2, 3, 4, 5, 6, 7, 8, 9]"
Swift 4.1
let digits = string.compactMap{Int(String($0))}
Swift 5 or later
We can use the new Character Property wholeNumberValue
https://developer.apple.com/documentation/swift/character/3127025-wholenumbervalue
let digits = string.compactMap{$0.wholeNumberValue}
let str = "123456789"
let intArray = map(str) { String($0).toInt() ?? 0 }
map()
iteratesCharacter
s instr
String($0)
convertsCharacter
toString
.toInt()
convertsString
toInt
. If failed(??
), use0
.
If you prefer for
loop, try:
let str = "123456789"
var intArray: [Int] = []
for chr in str {
intArray.append(String(chr).toInt() ?? 0)
}
OR, if you want to iterate indices of the String
:
let str = "123456789"
var intArray: [Int] = []
for i in indices(str) {
intArray.append(String(str[i]).toInt() ?? 0)
}