objective-c - obj-c 到 Swift 转换代码

Question

所以我正在尝试将一些 obj-c 代码转换为 swift，但我被困在其中的一部分。我怎样才能 swift 做这样的事情？

- (void)sometMethod:(NSString *)s {
NSString * crlfString = [s stringByAppendingString:@"\r\n"];
uint8_t *buf = (uint8_t *)[crlfString UTF8String];}

真正的问题是这一行

uint8_t *buf = (uint8_t *)[crlfString UTF8String];

Answer 1

你想用 UTF-8 缓冲区做什么？通常，将字符串直接转换为 NSData 对象会更方便。但你也可以将你的 Obj-C 代码一一翻译成 Swift。以下是两种变体:

import Foundation

func appendCRLFAndConvertToUTF8_1(s: String) -> NSData {
    let crlfString: NSString = s.stringByAppendingString("\r\n")
    let buffer = crlfString.UTF8String
    let bufferLength = crlfString.lengthOfBytesUsingEncoding(NSUTF8StringEncoding)
    let data = NSData(bytes: buffer, length: bufferLength)
    return data;
}

func appendCRLFAndConvertToUTF8_2(s: String) -> NSData {
    let crlfString = s + "\r\n"
    return crlfString.dataUsingEncoding(NSUTF8StringEncoding)!
}

let s = "Hello 😄"
let data1 = appendCRLFAndConvertToUTF8_1(s)
data1.description

let data2 = appendCRLFAndConvertToUTF8_2(s)
data2.description

data1 == data2

如果您想迭代 UTF-8 代码单元而不处理缓冲区，请使用类似的东西:

for codeUnit in String.utf8 {
    println(codeUnit) 
}