NSString、NSData、char* 类型之间的转换-备

时间:2024-05-24 11:35:32
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
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]; 说法二:
iOS中NSString转换成HEX(十六进制)-NSData转换成int

NSString *str = @"0xff055008";
//先以16为参数告诉strtoul字符串参数表示16进制数字,然后使用0x%X转为数字类型
unsigned long red = strtoul([str UTF8String],0,16);
//strtoul如果传入的字符开头是“0x”,那么第三个参数是0,也是会转为十六进制的,这样写也可以:
unsigned long red = strtoul([@"0x6587" UTF8String],0,0);
NSLog(@"转换完的数字为:%lx",red);

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
// 十六进制转换为普通字符串的。
+ (NSString *)stringFromHexString:(NSString *)hexString { //
  
char *myBuffer = (char *)malloc((int)[hexString length] / 2 + 1);
bzero(myBuffer, [hexString length] / 2 + 1);
for (int i = 0; i < [hexString length] - 1; i += 2) {
unsigned int anInt;
NSString * hexCharStr = [hexString substringWithRange:NSMakeRange(i, 2)];
NSScanner * scanner = [[[NSScanner alloc] initWithString:hexCharStr] autorelease];
[scanner scanHexInt:&anInt];
myBuffer[i / 2] = (char)anInt;
}
NSString *unicodeString = [NSString stringWithCString:myBuffer encoding:4];
NSLog(@"------字符串=======%@",unicodeString);
return unicodeString;
  
  
}
  
//普通字符串转换为十六进制的。
  
+ (NSString *)hexStringFromString:(NSString *)string{
NSData *myD = [string dataUsingEncoding:NSUTF8StringEncoding];
Byte *bytes = (Byte *)[myD bytes];
//下面是Byte 转换为16进制。
NSString *hexStr=@"";
for(int i=0;i<[myD length];i++)
  
{
NSString *newHexStr = [NSString stringWithFormat:@"%x",bytes[i]&0xff];///16进制数
  
if([newHexStr length]==1)
  
hexStr = [NSString stringWithFormat:@"%@0%@",hexStr,newHexStr];
  
else
  
hexStr = [NSString stringWithFormat:@"%@%@",hexStr,newHexStr];
}
return hexStr;
}
1
2
3
4
5
6
//int 转data
int i = 1;
NSData *data = [NSData dataWithBytes: &i length: sizeof(i)];
//data 转int
int i;
[data getBytes: &i length: sizeof(i)];