Swift turn a country code into a emoji flag via un

Question

I'm looking for a quick way to turn something like:

let germany = "DE" 

into

let flag = "\u{1f1e9}\u{1f1ea}"

ie, what's the mapping of D to 1f1e9 and E to 1f1ea I was looking at .utf8 for the string, but this returns an integer.

FWIW my general goal is to be able to take an arbitrary country code and get the corresponding emoji flag.

EDIT: I'm also fine with just holding a table that does this mapping if its available somewhere. I googled around but didn't find it.

Answer 1

Here's a general formula for turning a two-letter country code into its emoji flag:

func flag(country:String) -> String {
    let base = 127397
    var usv = String.UnicodeScalarView()
    for i in country.utf16 {
        usv.append(UnicodeScalar(base + Int(i)))
    }
    return String(usv)
}

let s = flag("DE")

EDIT Ooops, no need to pass through the nested String.UnicodeScalarView struct. It turns out that String has an append method for precisely this purpose. So:

func flag(country:String) -> String { 
    let base : UInt32 = 127397
    var s = ""
    for v in country.unicodeScalars {
        s.append(UnicodeScalar(base + v.value))
    }
    return s
}

EDIT Oooops again, in Swift 3 they took away the ability to append a UnicodeScalar to a String, and they made the UnicodeScalar initializer failable (Xcode 8 seed 6), so now it looks like this:

func flag(country:String) -> String {
    let base : UInt32 = 127397
    var s = ""
    for v in country.unicodeScalars {
        s.unicodeScalars.append(UnicodeScalar(base + v.value)!)
    }
    return String(s)
}

Answer 2

To give more insight into matt answer

Swift 2 version

public static func flag(countryCode: String) -> Character {
    let base = UnicodeScalar("                                                                    

                                                        
            

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Answer 3

Two optimizations of matt's answer.

• No need to pass through the nested String in Swift 4
• To avoid pass lower case string, I added uppercased()

Here is the code.

func flag(from country:String) -> String {
    let base : UInt32 = 127397
    var s = ""
    for v in country.uppercased().unicodeScalars {
        s.unicodeScalars.append(UnicodeScalar(base + v.value)!)
    }
    return s
}

Answer 4

For a more functional approach, using no mutable variables, use this:

private func flag(country: String) -> String {
    let base: UInt32 = 127397
    return country.unicodeScalars
        .flatMap({ UnicodeScalar(base + $0.value) })
        |> String.UnicodeScalarView.init
        |> String.init
}

Where the |> operator is the function application operator, working like a "pipe" for a more natural reading order: We take the scalars, map them into new scalars, turn that into a view, and that into a string.

It's defined like so:

infix operator |> : MultiplicationPrecedence
func |> <T, U>(left: T, right: (T) -> U) -> U {
    return right(left)
}

Without custom operators, we can still do without mutable state, like so:

private func flag(country: String) -> String {
    let base: UInt32 = 127397
    return String(String.UnicodeScalarView(
        country.unicodeScalars.flatMap({ UnicodeScalar(base + $0.value) })
    ))
}

But IMHO, this reads a little "backwards", since the natural flow of operations read neither out-in, nor in-out, but a little bit of both.

Answer 5

If anyone looking for solution in ObjectiveC here is convenient category:

@interface NSLocale (RREmoji)

+ (NSString *)emojiFlagForISOCountryCode:(NSString *)countryCode;

@end


@implementation NSLocale (RREmoji)


+ (NSString *)emojiFlagForISOCountryCode:(NSString *)countryCode {
    NSAssert(countryCode.length == 2, @"Expecting ISO country code");

    int base = 127462 -65;

    wchar_t bytes[2] = {
        base +[countryCode characterAtIndex:0],
        base +[countryCode characterAtIndex:1]
    };

    return [[NSString alloc] initWithBytes:bytes
                                    length:countryCode.length *sizeof(wchar_t)
                                  encoding:NSUTF32LittleEndianStringEncoding];
}


@end

test:

for ( NSString *countryCode in [NSLocale ISOCountryCodes] ) {
    NSLog(@"%@ - %@", [NSLocale emojiFlagForISOCountryCode:countryCode], countryCode);
}

output:

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