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)];