How to convert a String to UInt32 in Swift

Question

let temp: String = "0xffeeffff"

How to convert above String to UInt32, because I need to store it in the bitmap which only accept UInt32

check out this link http://stackoverflow.com/questions/30382414/swift-how-to-convert-string-to-uint — Lamour, Jan 04 '16 at 01:19
Possible duplicate of [Convert String to Uint32](http://stackoverflow.com/questions/34573609/convert-string-to-uint32) — ajshort, Jan 04 '16 at 01:44
so? you should select an answer to let people know what worked for you. — Devran Cosmo Uenal, Jan 21 '16 at 20:14

Devran Cosmo Uenal · Accepted Answer · 2016-01-04T02:33:56.117

4

Remove "0x" from your string to convert it to UInt32:

let temp   = "0xffeeffff"
let result = UInt32(String(temp.characters.dropFirst(2)), radix: 16)

edited Jan 04 '16 at 02:33

answered Jan 04 '16 at 01:20

Devran Cosmo Uenal

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thank you for your replying. But when I pass the result to the bitmapData[offset], you have to pass like "0xffeeffff" with "0x" – shixiaoz Jan 04 '16 at 02:12
@shixiaoz i've updated my answer. the "0x" is now removed while converting, but leaving `temp` as it is. – Devran Cosmo Uenal Jan 04 '16 at 02:15
1

@DevranCosmoUenal String("0xffeeffff".characters.suffix(8)) – Leo Dabus Jan 04 '16 at 02:22
1

@LeoDabus I was not sure if `temp` could also be `0xff` so I took the search-and-replace way. – Devran Cosmo Uenal Jan 04 '16 at 02:27
@LeoDabus `String("0xff".characters.suffix(8))` results `0xff`. `String(temp.characters.dropFirst(2))` would work. – Devran Cosmo Uenal Jan 04 '16 at 02:32
but it would've to start with 0x – Leo Dabus Jan 04 '16 at 02:33
1

can also check if it hasPrefix("0x") before dropping them – Leo Dabus Jan 04 '16 at 02:35

score 2 · Answer 2 · answered Jan 04 '16 at 09:21

hope this is help you...

extension String {
func toUInt() -> UInt? {
    if contains(self, "-") {
        return nil
    }
    return self.withCString { cptr -> UInt? in
        var endPtr : UnsafeMutablePointer<Int8> = nil
        errno = 0
        let result = strtoul(cptr, &endPtr, 10)
        if errno != 0 || endPtr.memory != 0 {
            return nil
        } else {
            return result
        }
    }
}
}

How to convert a String to UInt32 in Swift

2 Answers2