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);

// 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;
}

//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)];