本文介绍了常见的类型转换.
一.NSString和NSData的互相转换.
- NSString 转 NSData.
NSString *testStr1 = @"better";
NSData *testData1 = [testStr1 dataUsingEncoding:NSUTF8StringEncoding];
NSLog(@"testData:%@",testData1);
结果:
2017-06-06 17:37:44.950912+0800 test1[9204:3141182] testData:<62657474 6572>
- NSData 转 NSString.
NSString *testStr2 = [[NSString alloc] initWithData:testData1 encoding:NSUTF8StringEncoding];
NSLog(@"testStr:%@",testStr2);
结果:
2017-06-06 17:37:44.951103+0800 test1[9204:3141182] testStr:better
二.NSData和Byte互相转换.
- NSData 转 Byte数组.
NSString *testStr3 = @"better";
NSData *testData2 = [testStr3 dataUsingEncoding: NSUTF8StringEncoding];
Byte *testByte1 = (Byte *)[testData2 bytes];
for (int i = 0; i < [testData2 length]; i++)
{
NSLog(@"%d",testByte1[i]);
}
结果:
2017-06-06 17:37:44.951213+0800 test1[9204:3141182] 98
2017-06-06 17:37:44.951250+0800 test1[9204:3141182] 101
2017-06-06 17:37:44.951283+0800 test1[9204:3141182] 116
2017-06-06 17:37:44.951314+0800 test1[9204:3141182] 116
2017-06-06 17:37:44.951345+0800 test1[9204:3141182] 101
2017-06-06 17:37:44.951376+0800 test1[9204:3141182] 114
说明:
NSData默认含有bytes的只读属性,可直接调用.
@property (readonly) const void *bytes NS_RETURNS_INNER_POINTER;
- Byte数组 转 NSData.
Byte byteArr[] = {98,101,116,116,101,114};
NSData *testData3 = [[NSData alloc] initWithBytes:byteArr length:sizeof(byteArr)/sizeof(Byte)];
NSLog(@"%@",testData3);
结果:
2017-06-06 17:44:21.302122+0800 test1[9209:3143384] <62657474 6572>
三. 十六进制和十进制互相转换.
- 十六进制 转 十进制 (
系统方法)
NSUInteger testData4 = strtoul([testHexStr UTF8String],0,16);
NSLog(@"%zd",testData4);
结果:
2017-06-06 18:22:00.746316+0800 test1[9286:3154681] 190
strtoul说明:
//参数1：字符串起始地址.
//参数2：返回字符串有效数字的结束地址,这也是为什么要用二级指针的原因.
//参数3：转换基数.当base=0,自动判断字符串的类型,并按10进制输出.
strtoul(const char *__str, char **__endptr, int __base);
- 十进制 转 十六进制 (
系统方法)
NSString *testHexStr = [NSString stringWithFormat:@"%@",[[NSString alloc] initWithFormat:@"%x",190]];
NSLog(@"%@",testHexStr);
结果:
2017-06-06 18:22:00.746256+0800 test1[9286:3154681] be
说明:
转换结果不带0X前缀,如果需要带0X前缀,且是小写字母,使用%#x打印格式,若是大写字母,使用%#X打印格式.
- 十六进制 转 十进制 (自己实现 -- 出自<iOS开发>之类型转换)
// 十六进制转十进制
- (NSString *)convertDecimalWithHexStr:(NSString *)hexStr
{
int decimal = 0;
UniChar hexChar = ' ';
NSInteger hexLength = [hexStr length];
for (NSInteger i = 0; i < hexLength; i++)
{
int base;
hexChar = [hexStr characterAtIndex:i];
if (hexChar >= '0' && hexChar <= '9')
{
// 0 的Ascll - 48
base = (hexChar - 48);
}
else if (hexChar >= 'A' && hexChar <= 'F')
{
// A 的Ascll - 65
base = (hexChar - 55);
}
else
{
// a 的Ascll - 97
base = (hexChar - 87);
}
decimal = decimal + base * pow(16, hexLength - i - 1);
}
return [NSString stringWithFormat:@"%d",decimal];
}
调用:
NSLog(@"%@",[self convertDecimalWithHexStr:@"AbCdE"]);
结果:
2017-06-07 00:59:06.852111+0800 十六进制转十进制[9450:3194324] 703710
- 十进制 转 十六进制 (自己实现 -- 出自<iOS开发>之类型转换)
// 十进制转十六进制
- (NSString *)convertHexStrWithDecimal:(NSInteger)decimal
{
NSMutableString *HexStr = [NSMutableString string];
NSString *currentStr = [NSString string];
// 余数
NSInteger remainder = 0;
// 商
NSInteger quotient = 0;
do
{
// 余数
remainder = decimal % 16;
quotient = decimal / 16;
switch (remainder)
{
case 10:
currentStr = @"a";
break;
case 11:
currentStr = @"b";
break;
case 12:
currentStr = @"c";
break;
case 13:
currentStr = @"d";
break;
case 14:
currentStr = @"e";
break;
case 15:
currentStr = @"f";
break;
default:
currentStr = [NSString stringWithFormat:@"%zd",remainder];
break;
}
// 将获得的字符串插入第一个位置
[HexStr insertString:currentStr atIndex:0];
// 将商作为新的计算值.
decimal = quotient;
} while (quotient != 0);
return HexStr;
}
调用:
NSLog(@"%@",[self convertHexStrWithDecimal:703710]);
结果:
2017-06-07 00:59:06.851867+0800 十六进制转十进制[9450:3194324] abcde
