iOS NSString、NSData 、Char *之间的转换

释放双眼,带上耳机,听听看~!
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''就结束,而是一定会拷贝完n个字节
2. NSString 转化为 char *
NSString * str= @“Test”;
const char * a =[str UTF8String];

3.char * 转化为 NSString
NSString *str=[NSString stringWithCString  encoding:NSUTF8StringEncoding];
4. 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
5. NSData 转化 char *
NSData data ;
char* a=[data bytes];
6. NSData 转化 NSString;
NSData* data;
NSString* aStr= [NSString alloc] initWithData:data   encoding:NSASCIIStringEncoding];
7. NSString 转化 NSData对象
NSData* xmlData = [@"testdata" dataUsingEncoding:NSUTF8StringEncoding];

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()];
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];

 

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