NSString 的相关转换

NSString conversions

1. NSString 转化为 UNICODE String:

(NSString *)fname = @"Test";
char fnameStr[10];
memcpy(fnameStr, [fname cStringUsingEncoding:NSUnicodeStringEncoding], 2*([fname length]));

与 strcpy 相比，memcpy 并不是遇到’\0’ 就结束，而是一定会拷贝完 n 个字节

1. NSString 转化为 char *

NSString *str = @"Test";
const char * a =[str UTF8String];

1. char * 转化为 NSString

NSString *str = [NSString stringWithCString encoding:NSUTF8StringEncoding];

1. char * 转化 NSData

• 方法一

   char * a = (char*)malloc(sizeof(byte)*16);
   NSData *data = [NSData dataWithBytes: a   length:strlen(a)];

• 方法二
  • 转换为NSString： - (id)initWithUTF8String:(const char *)bytes
  • 然后用NSString的 - (NSData *)dataUsingEncoding:(NSStringEncoding)encoding

1. NSData 转化 char </strong> NSData data ； char a=[data bytes];

2. NSData 转化 NSString;</pre>

NSData* data;

NSString* aStr= ［NSString alloc] initWithData:data   encoding:NSASCIIStringEncoding];

7. NSString 转化 NSData对象

NSData* xmlData = [@"testdata" dataUsingEncoding:NSUTF8StringEncoding];

http://blog.sina.com.cn/s/articlelist_1256141290_14_1.html

NSString 转化 NSURL  

 //NSURL *url = [NSURL URLWithString:[str   stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding ]];

NSString *urlString=[@"http://www.google.com/search?client=safari&rls=en&q=搜索&ie=UTF-8&oe=UTF-8" stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSURL 转化 NSString

NSURL *url=[NSURL URLWithString:urlString];

NSString *s=[[url absoluteString] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSArray *arr = [urlStr componentsSeparatedByString:@"&"]; 
NSURL *url = [NSURL URLWithString:[[arr objectAtIndex:0] stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding ]]; 
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url]; 
[request setHTTPMethod:@"POST"]; 

NSMutableArray *_array = [[NSMutableArray alloc] initWithCapacity:0]; 
for (int i = 1; i < [arr count]; ++i ){ 
NSString *str = [arr objectAtIndex:i]; 
[_array addObject:str]; 
} 
[_array componentsJoinedByString:@"&"]; 
NSData *data = [[_array componentsJoinedByString:@"&"] dataUsingEncoding: NSASCIIStringEncoding]; 
[request setHTTPBody:data];
// 发送请求并获得服务器反馈的数据
NSData *urldata = [AESEnCDeCViewController Get:url];

// 第一种 转换NSData数据到char*字符串
char * test = (char*)[urldata bytes];
std::string old = deaes(test);

// 第二种 转换NSData到UTF8编码的NSString中再转换为char*字符串
//    NSString *desStr = [[NSString alloc] initWithData:urldata encoding:NSUTF8StringEncoding];
//    const char *desresult = [desStr UTF8String];
//    std::string old = deaes(desresult);

// 解密字字符串到明文
NSString *oldstr = [[NSString alloc] initWithCString:old.c_str()];</pre>

很多时候软件读取的中文网页编码集是 gb2312，所以显示出来的是乱码。这时需要将 NSString 文字编码转换

1 NSURL *url = [NSURL URLWithString:urlStr];
2 NSData *data = [NSData dataWithContentsOfURL:url];
3 NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);
4 NSString *retStr = [[NSString alloc] initWithData:data encoding:enc];