NSPasteboard UTF-16 nonsense

main.m

#import <Cocoa/Cocoa.h>
#import <UniformTypeIdentifiers/UniformTypeIdentifiers.h>

@implementation NSData (NSArrayConversion)
- (NSArray<NSNumber*>*)byteArray {
    NSMutableArray<NSNumber*> *a = [NSMutableArray arrayWithCapacity:[self length]];

    const unsigned char *bytes = [self bytes];
    for (int i = 0; i < [self length]; i++) {
        a[i] = [[NSNumber alloc] initWithUnsignedChar:bytes[i]];
    }

    return a;
}
@end

@implementation NSArray (SwiftDescription)
- (NSString *)swiftDescription {
    NSMutableString *s = [[NSMutableString alloc] init];
    [s appendString:@"["];
    [s appendString:[self componentsJoinedByString:@", "]];
    [s appendString:@"]"];

    return s;
}
@end

@implementation NSString (SwiftDescription)
- (NSString *)swiftDescription {
    NSMutableString *s = [[NSMutableString alloc] init];
    [s appendString:@"\""];
    [s appendString: self];
    [s appendString:@"\""];

    [s replaceOccurrencesOfString:@"\0" withString:@"\\0" options:0 range:NSMakeRange(0, [s length])];
    [s applyTransform:@"[:Cc:] Any-Hex/Perl" reverse:false range:NSMakeRange(0, [s length]) updatedRange:nil];
    [s replaceOccurrencesOfString:@"\\x{" withString:@"\\u{" options:0 range:NSMakeRange(0, [s length])];

    NSRegularExpression *singleDigitCodepoint = [[NSRegularExpression alloc] initWithPattern:@"\\\\u\\{([a-zA-Z0-9])\\}" options:0 error:nil];

    [singleDigitCodepoint replaceMatchesInString:s options:0 range:NSMakeRange(0, [s length]) withTemplate:@"\\\\u{0$1}"];

    return s;
}
@end

void
print(NSString *format, ...) {
    va_list args;
    va_start(args, format);

    NSString *out = [[NSString alloc] initWithFormat:format arguments:args];
    fprintf(stderr, "%s\n", [out UTF8String]);

    va_end(args);
}

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        [[[NSAppleScript alloc] initWithSource:@"set the clipboard to \"ABC\""] executeAndReturnError:nil];

        NSPasteboard *pasteboard = NSPasteboard.generalPasteboard;
        // [pasteboard clearContents];
        // NSData *data = [@"ABC" dataUsingEncoding:NSUTF16LittleEndianStringEncoding];
        // NSString *utf16 = [UTTypeUTF16PlainText identifier];
        // assert([utf16 isEqualTo:@"public.utf16-plain-text"]);
        // [pasteboard setData:data forType:utf16];

        for (NSPasteboardType type in pasteboard.types) {
        // for (NSPasteboardType type in pasteboard.pasteboardItems.firstObject.types) {
            NSData *data = [pasteboard dataForType:type];
            NSString *s = [pasteboard stringForType:type];
            print(@"%@ %@ %@", type, [[data byteArray] swiftDescription], [s swiftDescription]);
        }
    }

    return 0;
}

main.swift

import Cocoa
import UniformTypeIdentifiers

NSAppleScript(source: "set the clipboard to \"ABC\"")?.executeAndReturnError(nil)

let pasteboard = NSPasteboard.general
// pasteboard.clearContents()
// let data = "ABC".data(using: .utf16LittleEndian)!
// let utf16 = NSPasteboard.PasteboardType(UTType.utf16PlainText.identifier)
// assert(utf16.rawValue == "public.utf16-plain-text")
// pasteboard.setData(data, forType: utf16)

for type in pasteboard.types ?? [] {
// for type in pasteboard.pasteboardItems?.first?.types ?? [] {
    let d: String
    if let data = pasteboard.data(forType: type) {
        d = Array(data).debugDescription
    } else {
        d = "(null)"
    }

    let s = pasteboard.string(forType: type)?.debugDescription ?? "(null)"
    print(type.rawValue, d, s)
}

objc-applescript-item.txt

public.utf16-plain-text [65, 0, 66, 0, 67, 0] "A\0B\0C\0"
public.utf8-plain-text [65, 66, 67] "ABC"
com.apple.traditional-mac-plain-text [65, 66, 67] "ABC"
dyn.ah62d4rv4gk81g7d3ru [1, 0, 0, 0, 0, 0, 16, 0, 14, 0, 3, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 0] "\u{01}\0\0\0\0\0\u{10}\0\u{0E}\0\u{03}\0\0\0\u{0C}\0\0\0\0\0\0\0"

objc-applescript-noitem.txt

public.utf16-plain-text [65, 0, 66, 0, 67, 0] "A\0B\0C\0"
CorePasteboardFlavorType 0x75747874 [65, 0, 66, 0, 67, 0] "A\0B\0C\0"
public.utf8-plain-text [65, 66, 67] "ABC"
NSStringPboardType [65, 66, 67] "ABC"
com.apple.traditional-mac-plain-text [65, 66, 67] "ABC"
CorePasteboardFlavorType 0x54455854 [65, 66, 67] "ABC"
dyn.ah62d4rv4gk81g7d3ru [1, 0, 0, 0, 0, 0, 16, 0, 14, 0, 3, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 0] "\u{01}\0\0\0\0\0\u{10}\0\u{0E}\0\u{03}\0\0\0\u{0C}\0\0\0\0\0\0\0"
CorePasteboardFlavorType 0x7374796C [1, 0, 0, 0, 0, 0, 16, 0, 14, 0, 3, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 0] "\u{01}\0\0\0\0\0\u{10}\0\u{0E}\0\u{03}\0\0\0\u{0C}\0\0\0\0\0\0\0"

objc-setdata-item.txt

public.utf16-plain-text [65, 0, 66, 0, 67, 0] "A\0B\0C\0"
public.utf8-plain-text [65, 66, 67] "ABC"

objc-setdata-noitem.txt

public.utf16-plain-text [65, 0, 66, 0, 67, 0] "A\0B\0C\0"
CorePasteboardFlavorType 0x75747874 [65, 0, 66, 0, 67, 0] "A\0B\0C\0"
public.utf8-plain-text [65, 66, 67] "ABC"
NSStringPboardType [65, 66, 67] "ABC"

swift-applescript-item.txt

public.utf16-plain-text [65, 0, 66, 0, 67, 0] "A\0B\0C\0"
public.utf8-plain-text [65, 66, 67] "ABC"
com.apple.traditional-mac-plain-text [65, 66, 67] "ABC"
dyn.ah62d4rv4gk81g7d3ru [1, 0, 0, 0, 0, 0, 16, 0, 14, 0, 3, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 0] "\u{01}\0\0\0\0\0\u{10}\0\u{0E}\0\u{03}\0\0\0\u{0C}\0\0\0\0\0\0\0"

swift-applescript-noitem.txt

public.utf16-plain-text [65, 0, 66, 0, 67, 0] "A\0B\0C\0"
CorePasteboardFlavorType 0x75747874 [65, 0, 66, 0, 67, 0] "A\0B\0C\0"
public.utf8-plain-text [65, 66, 67] "ABC"
NSStringPboardType [65, 66, 67] "ABC"
com.apple.traditional-mac-plain-text [65, 66, 67] "ABC"
CorePasteboardFlavorType 0x54455854 [65, 66, 67] "ABC"
dyn.ah62d4rv4gk81g7d3ru [1, 0, 0, 0, 0, 0, 16, 0, 14, 0, 3, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 0] "\u{01}\0\0\0\0\0\u{10}\0\u{0E}\0\u{03}\0\0\0\u{0C}\0\0\0\0\0\0\0"
CorePasteboardFlavorType 0x7374796C [1, 0, 0, 0, 0, 0, 16, 0, 14, 0, 3, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 0] "\u{01}\0\0\0\0\0\u{10}\0\u{0E}\0\u{03}\0\0\0\u{0C}\0\0\0\0\0\0\0"

swift-setdata-item.txt

public.utf16-plain-text [65, 0, 66, 0, 67, 0] "A\0B\0C\0"
public.utf8-plain-text [65, 66, 67] "ABC"

swift-setdata-noitem.txt

public.utf16-plain-text [65, 0, 66, 0, 67, 0] "A\0B\0C\0"
CorePasteboardFlavorType 0x75747874 [65, 0, 66, 0, 67, 0] "A\0B\0C\0"
public.utf8-plain-text [65, 66, 67] "ABC"
NSStringPboardType [65, 66, 67] "ABC"