BPlist-and-NSKeyedUnarchiver

> Tool for deserializing binary plist files and NSKeyedUnarchiver-coded files.

Origin and licensing

Based on the implementation in Apple's open-sourced CFBinaryPList.c, licensed under APSL v2.0.
As a result, this code is likely a derivative work of said code,
therefore this code and all changes to it will be made public,
along with a copy of the
APSL v2 in OriginalCode.APSL.LICENSE.

However, as this code does not use any of the original C code, original
or modified, I feel mildly comfortable in licensing this project as MIT, as
long as the source-publishing criteria are met.

Usage

$3

These examples show reading a file (in Node and in the Browser)
and parsing the top-level BPlist object from it.

#### Node

``ts
const { readFile } = require('node:fs/promises');
const { Reader } = require('@skgrush/bplist-and-nskeyedunarchiver/bplist');
const { buildLeveledLogger, LogLevel } = require('@skgrush/bplist-and-nskeyedunarchiver/share');

async function readBPlistFromFilePath(filePath: string) {
const nodeBuffer = await readFile(filePath);
const arrayBuffer = nodeBuffer.buffer.slice(
nodeBuffer.byteoffset,
nodeBuffer.byteOffset + nodeBuffer.byteLength,
);

const logger = buildLeveledLogger({ logger: console, level: LogLevel.warn });
const reader = new Reader(arrayBuffer, logger);

const object = reader.buildTopLevelObject();
}
`

#### Browser

`ts
import { Reader } from '@skgrush/bplist-and-nskeyedunarchiver/bplist/reader';

async function readBPlistFromBlob(blob: Blob) {
const arrayBuffer = await blob.arrayBuffer();

const logger = buildLeveledLogger({ logger: console, level: LogLevel.warn });
const reader = new Reader(arrayBuffer, logger);

return reader.buildTopLevelObject();
}
`

$3

This example provides examples of how to unarchive a custom class containing some native NS types,
including arrays of other custom class.

`ts
import { Reader } from '@skgrush/bplist-and-nskeyedunarchiver/bplist/reader';
import { $ObjectsMap, IArchivedInstance, KeyedUnarchiver, NSArrayCoder, NSDateCoder, NSUUIDCoder } from '@skgrush/bplist-and-nskeyedunarchiver/NSKeyedUnarchiver';


async function readMyClassFromBlob(blob: Blob) {
// see BPlist example above
const bplistObject = await readBPlistFromBlob(blob);

// top level objects can be any type, so you may want to filter out any of the possible types
if (!bplistObject || typeof bplistObject !== 'object' || !('$archiver' in bplistObject)) {
throw new Error('Invalid BPList object file');
}

return MyDecoder.unarchiveObject(MyDecoder, bplistObject);
}


class MyDecoder extends KeyedUnarchiver {
static readonly $classname = 'MyNamespace.MyClassname';

constructor(
readonly $objects: $ObjectsMap,
readonly data: IArchivedInstance,
) {
super();
}

static initForReadingDataFrom($objects: $ObjectsMap, data: IArchivedInstance) {
return new MyDecoder($objects, data);
}

decode(): MyClass {

// decode the properties of your class
const myTimestamp = this.decodeObjectOf(NSDateCoder, 'myTimestamp', true);
const myName = this.decodeString('myName', true);
const arry = this.decodeObjectOf([NSArrayCoder, SomeOtherDecoder], 'arrayOfSomething', true) as SomeOtherClass[];

return new MyClass(myTimestamp, myName, arry);
}
}

class SomeOtherDecoder extends KeyedUnarchiver {
static readonly $classname = 'MyNamespace.SomeOtherClass';

constructor(
readonly $objects: $ObjectsMap,
readonly data: IArchivedInstance,
) {
super();
}

static initForReadingDataFrom($objects: $ObjectsMap, data: IArchivedInstance) {
return new SomeOtherDecoder($objects, data);
}

decode(): SomeOtherClass {
const myUuid = this.decodeObjectOf(NSUuidCoder, 'myUuid', true);
const myFloat = this.decodeFloat('myFloat');

return new SomeOtherClass(myUuid);
}

}
``