[英]How to effectively represent htonl in swift?
I tried to use the socket
to transfer large files, and the backend agreed on the transfer method. 我试图使用
socket
传输大文件,后端同意传输方法。 Objective C
can pass the length
correctly to the server, but I can't pass the correct length
on Swift
. Objective C
可以正确地将length
传递给服务器,但我无法在Swift
上传递正确的length
。
I will show my two pieces of code below. 我将在下面展示我的两段代码。
NSMutableData *sendData = [NSMutableData data];
NSData *data = [message dataUsingEncoding:NSUTF8StringEncoding];
uint8_t array[] = {1};
NSData *typeData = [[NSData alloc] initWithBytes:array length:sizeof(array)];
[sendData appendData:typeData];
uint32_t length = htonl(data.length);
NSData *lengthData = [[NSData alloc] initWithBytes:&length length:sizeof(int)];
[sendData appendData:lengthData];
[sendData appendData:data];
self.client.userData = fileId;
[self.client writeData:sendData withTimeout:-1 tag:11];
let sendData = NSMutableData()
let data = messageField.text!.data(using: .utf8)
let typeData = Data.init(bytes: [1], count: MemoryLayout<Int>.size)
sendData.append(typeData)
let length: UInt32 = 20
var convertedNumber: UInt32 = length.bigEndian
let lengthData = Data.init(bytes: &convertedNumber, count: MemoryLayout<UInt32>.size)
sendData.append(lengthData)
sendData.append(data!)
clientSocket.write(sendData as Data, withTimeout: -1, tag: 0)
byte type = in.readByte();
int length = in.readInt();
Objective C
code is OK, how can I convert it to swift
. Objective C
代码没问题,如何将其转换为swift
。
length.bigEndian
is the correct method to convert an integer to its big-endian representation. length.bigEndian
是将整数转换为big-endian表示的正确方法。 But there is an error at 但是有一个错误
let typeData = Data.init(bytes: [1], count: MemoryLayout<Int>.size)
which creates 8 bytes data (most of which are undefined). 它创建了8个字节的数据(其中大部分是未定义的)。
Note that the same can be achieved more directly, without using NSMutableData
. 请注意,可以更直接地实现相同,而无需使用
NSMutableData
。 Here is an example: 这是一个例子:
let message = "abc"
let msgData = Data(message.utf8)
var sendData = Data()
// Append type:
sendData.append(1)
// Append message length:
let length = UInt32(msgData.count).bigEndian
withUnsafeBytes(of: length) { sendData.append(contentsOf: $0) }
// Append message:
sendData.append(msgData)
print(sendData as NSData) // <01000000 03616263>
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