Sample code for creating NSData backed CMBlockBuffer using customBlockAllocator, in Swift.

CMBlockBufferHelper.swift

//
//  CMBlockBufferHelper.swift
//
//  Created by Simon Kim on 2016. 9. 6..
//  Copyright © 2016년 DZPub.com. All rights reserved.
//

import Foundation
import CoreMedia
/**
 * Sample code for creating NSData backed CMBlockBuffer using customBlockAllocator, in Swift.
 *
 * Example:
     func testExample() {
       let bytes: [UInt8] = [ 1, 2, 3, 4, 5 ]
       
       let data = NSData(bytes: bytes, length: bytes.count)
       let bb = CMBlockBufferHelper.sharedInstance.create(with: data)
       XCTAssert(CMBlockBufferGetDataLength(bb!) == bytes.count)
       
       CMBlockBufferAssureBlockMemory(bb!)
       var totalLength:Int = 0
       var dataPointer: UnsafeMutablePointer<Int8>? = nil
       XCTAssert(CMBlockBufferGetDataPointer(bb!, 0, nil, &totalLength, &dataPointer) == noErr)
       XCTAssert(totalLength == bytes.count, "totalLength \(totalLength) != \(bytes.count)")
       XCTAssert(UnsafeRawPointer(dataPointer) == data.bytes, "dataPointer \(dataPointer) != \(data.bytes)")
     }
 *
 */
class CMBlockBufferHelper {

    static var sharedInstance = {
        return CMBlockBufferHelper()
    }()
    
    var holder: [NSData] = []
    
    func retain(_ data: NSData) {
        holder.append(data)
    }
    
    func release(pointer:UnsafeRawPointer) {
        if let index = holder.index(where: { $0.bytes == pointer }) {
            holder.remove(at: index)
        }
    }
    
    func blockSource(with bytes: UnsafeMutableRawPointer) -> CMBlockBufferCustomBlockSource {
        return CMBlockBufferCustomBlockSource(
            version: kCMBlockBufferCustomBlockSourceVersion,
            AllocateBlock: { (refCon, size) -> UnsafeMutableRawPointer? in
                print("AllocateBlock:\(refCon)")
                return refCon
            }, FreeBlock: { (refCon, memoryBlock, size) in
                print("FreeBlock:\(memoryBlock)")
                CMBlockBufferHelper.sharedInstance.release(pointer:memoryBlock)
            }, refCon: bytes)
    }
    
    func create(with data:NSData) -> CMBlockBuffer? {
        retain(data)
        
        var blockSource = self.blockSource(with: UnsafeMutableRawPointer(mutating: data.bytes))
        
        var bb: CMBlockBuffer? = nil
        let status = CMBlockBufferCreateWithMemoryBlock(nil, nil, data.length, nil, &blockSource, 0, data.length, 0, &bb)
        if status != noErr {
            print("CMBlockBufferCreateWithMemoryBlock(\(data) failed:\(status)")
            release(pointer: data.bytes)
        }
        return bb
    }
}

Thanks for this!