字节流NSData（OC）、Data(Swift);

1、不同类型数据拼接字节流（拼包）UInt8、UInt16、UInt32组成的数据流拼接；

var ar: [UInt8] = Array.init(repeating: 0, count: 4)

ar[0] = 15

ar[1] = 13

let aa_ar = Data(bytes: ar, count: ar.count)

var br: [UInt16] = Array.init(repeating: 0, count: 4)

br[0] = 2

br[1] = 1

br[2] = 21474

br[3] = 235

let ba_ar = Data(bytes: br, count: br.count * 2)

var cr: [UInt32] = Array.init(repeating: 0, count: 4)

cr[0] = 3454

let ca_ar = Data(bytes: cr, count: cr.count * 4)

let data = aa_ar + ba_ar + ca_ar

print("\(ar)--\(aa_ar)--\(br)--\(ba_ar)--\(ba_ar)--\(cr)--\(ca_ar)--------\(data)")

[15, 13, 0, 0]--4 bytes--[2, 1, 21474, 235]--8 bytes--8 bytes--[3454, 0, 0, 0]--16 bytes--------28 bytes

data即为不同类型数据拼接成的字节流；

2、字节流还原为相应的数据（拆包）

var unpackingNum: UInt8 = 0

data[1..<2].withUnsafeBytes { rawBufferPointer in

if let rawPointer = rawBufferPointer.baseAddress {

unpackingNum = rawPointer.load(as: UInt8.self)

}

}

var unpackingNum1: UInt16 = 0

ba_ar[10..<12].withUnsafeBytes { rawBufferPointer in

if let rawPointer = rawBufferPointer.baseAddress {

unpackingNum1 = rawPointer.load(as: UInt16.self)

}

}

var unpackingNum2: UInt32 = 0

data[12..<16].withUnsafeBytes { rawBufferPointer in

if let rawPointer = rawBufferPointer.baseAddress {

unpackingNum2 = rawPointer.load(as: UInt32.self)

}

}

print("-----\(unpackingNum)-----\(unpackingNum1) -----\(unpackingNum2)")

-----13-----235 -----3454

完成相应解包过程；