之前在java上写过String转为byte数组的代码，后来在开发iPhone程序的时候，发现也需要把NSString转为byte数组，并且需要达到跟java程序兼容。但是发现java自身的默认编码机制为iso-8859-1，而ios的默认编码机制为utf-8，所以直接编码并不能达到两者兼容的问题。后来查阅相关资料，最后解决了编码兼容的问题，而且中英文都通用。
如下为java代码：
String str = "你好啊,aBc!"; ByteArrayOutputStream baos = new ByteArrayOutputStream(); DataOutputStream outputstream = new DataOutputStream(baos); outputstream.writeChars(str); byte[] contents = baos.toByteArray(); for (int i = 0; i < contents.length; i++) { System.out.println("contents:"+contents[i]); } 最后打印为：
contents:79 contents:96 contents:89 contents:125 contents:85 contents:74 contents:0 contents:44 contents:0 contents:97 contents:0 contents:66 contents:0 contents:99 contents:0 contents:33 ios代码 ：
NSString *str = @"你好啊,aBc!"; NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding(NSUTF16BigEndianStringEncoding); NSData *data = [str dataUsingEncoding:enc]; Byte *byte = (Byte *)[data bytes]; for (int i=0 ; i<[data length]; i++) { NSLog(@"byte = %d",byte[i]); } 最后打印结果为：
2012-07-19 10:07:46.967 encoding[593:f803] byte = 79 2012-07-19 10:07:46.969 encoding[593:f803] byte = 96 2012-07-19 10:07:46.969 encoding[593:f803] byte = 89 2012-07-19 10:07:46.970 encoding[593:f803] byte = 125 2012-07-19 10:07:46.970 encoding[593:f803] byte = 85 2012-07-19 10:07:46.970 encoding[593:f803] byte = 74 2012-07-19 10:07:46.970 encoding[593:f803] byte = 0 2012-07-19 10:07:46.971 encoding[593:f803] byte = 44 2012-07-19 10:07:46.971 encoding[593:f803] byte = 0 2012-07-19 10:07:46.971 encoding[593:f803] byte = 97 2012-07-19 10:07:46.971 encoding[593:f803] byte = 0 2012-07-19 10:07:46.972 encoding[593:f803] byte = 66 2012-07-19 10:07:46.972 encoding[593:f803] byte = 0 2012-07-19 10:07:46.972 encoding[593:f803] byte = 99 2012-07-19 10:07:46.972 encoding[593:f803] byte = 0 2012-07-19 10:07:46.973 encoding[593:f803] byte = 33
