Objective C 各种数据类型转换笔记大全
这个笔记，是为了让自己想不起的时候随时可以回顾一下，我不会说是因为自己懒不想记的 ·。·
以后会一直添加工作学习期间遇见的类型转换在这里～～
欢迎收录查阅～～～
Part 1. NSString字符串相关转化
ASCII码互转NSString
//1.ASCII码转NSString
unichar ch =65;
NSString *str =[NSString stringWithUTF8String:(char *)&ch];
//-->A
// ASCII to NSString
int asciiCode = 65;
NSString *string = [NSString stringWithFormat:@"%c", asciiCode]; // A
//-->A
//2.NSString转ASCII码
NSString *string = @"]";
int asciiCode = [string characterAtIndex:0];
//-->93
NSString 互转 char*
//NSString转char
//方法一
NSString *t = @"字符串";
const char *t2 =[t UTF8String];
//方法二
NSString * cocoaString = @"My NSString";
const char * myCstring = [cocoaString cStringUsingEncoding:NSUTF8StringEncoding];
//方法三
NSString *t = @"字符串1";
char mychar[100];
strcpy(mychar,(char *)[t UTF8String]);
//Char转NSString
//方法一
NSString * cocoaString = [[NSString alloc] initWithCString:mychar encoding:NSUTF8StringEncoding];
//方法二
const char * cString = "Hello";
NSString *TempString =[NSString stringWithFormat:@"%s",cString];
//方法三
const char * cString = "Hello";
NSString *str=[NSString stringWithCString:cString encoding:NSUTF8StringEncoding];
NSData 互转 char*
//Char*转NSData
//方法一
char * postData = "TEST";
NSData *data = [NSData dataWithBytes:postData length:strlen(postData)];
//方法二 先转NSString再转data
//NSData转Char*
[data bytes];
NSString 互转 NSData
//NSString转NSData
NSData *data =[str dataUsingEncoding:NSUTF8StringEncoding];
//NSData转NSString
NSString * str =[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSDictionary互转NSData
//dic转data
NSData *datax= [NSJSONSerialization dataWithJSONObject:jsonDic options:NSJSONWritingPrettyPrinted error:nil];
//data转dic
NSDictionary *dictionary =[NSJSONSerialization JSONObjectWithData:datax options:NSJSONReadingMutableLeaves error:nil];
十六进制转十进制
// 十六进制格式字符串(带不带0x都可)转成数字
unsigned int outVal;
NSScanner* scanner = [NSScanner scannerWithString:@"0x83"];
[scanner scanHexInt:&outVal];
NSLog(@"%d", outVal);
//-->131
十六进制转NSString
NSString * str = @"68656C6C6F";
NSMutableString * newString = [[NSMutableString alloc] init] ;
int i = 0;
while (i < [str length])
{
NSString * hexChar = [str substringWithRange: NSMakeRange(i, 2)];
int value = 0;
sscanf([hexChar cStringUsingEncoding:NSASCIIStringEncoding], "%x", &value);
[newString appendFormat:@"%c", (char)value];
i+=2;
}
NSLog(@"new str :%@",newString);
//-->new str :hello
NSString互转NSNumber
//NSString转NSNumber
//方法一
NSString * str = @"890909";
// 字符串转为NSInteger类型
NSInteger num = [str integerValue];
// 字符串转为NSNumber对象类型
NSNumber * nums = @(num);
//方法二，简化写法
NSNumber * nums = @([str integerValue]);
//NSNumber转NSString
NSNumberFormatter *number = [[NSNumberFormatter alloc] init];
NSString *b = [number stringFromNumber:nums];
-
字符串转int
NSString *string = @"123"; int intString = [string intValue]; -
int转字符串
- NSString *stringInt = [NSString stringWithFormat:@"%d",intString]; -
字符串转float
float floatString = [string floatValue]; -
float转字符串
NSString *stringFloat = [NSString stringWithFormat:@"%f",floatString]; long longValue = 104024; -
long 型转换字符串
NSNumber *longNumber = [NSNumber numberWithLong:longValue]; NSString *longStr = [longNumber stringValue]; -
long long 型转换字符串
NSNumber *longlongNumber = [NSNumber numberWithLongLong:longValue]; NSString *longlongStr = [longlongNumber stringValue]; -
字符串转long
[str longLongValue];
Objective C Char *,Const Char *,Cstring,CFString互转
Mark:之前的笔记，现在挪到这边。
-1. NSString转cstring
NSString *string1 = @"i am NSString";
NSLog(@"To cString : %s",[string1 UTF8String]);
-2. Const Char,Char转NSString
const char *cString = "i am const CString";
char *cString2 = "I am char";
NSLog(@"TO NSString1: %@",[NSString stringWithUTF8String:cString]);
NSLog(@"TO NSString2: %@",[NSString stringWithUTF8String:cString2]);
-3. Const Char 转Char
char* 表示一个指针变量，并且这个变量是可以被改变的。
const char*表示一个限定不会被改变的指针变量(意思是指针指向的内容不可变，但指针本身可以再赋值)
//方法一 strdup
//strdup()在内部调用了malloc()为变量分配内存，不需要使用返回的字符串时，需要用free()释放相应的内存空间
const char *cString = "i am const CString";
char *string2 = strdup(cString);
NSLog(@"To char1: %s",string2);
free(string2);
NSLog(@"To char2: %s",string2);
//方法二：强转const char
char *string3 = (char *)cString;
NSLog(@"To char3: %s",string3);
-4. Char 转Const Char
//强转
char *string4 = "I am Char";
const char *cString = string4;
NSLog(@"To const char：%s",cString);
-5. NSString 互转CFString
NSString *aNSString = @"NSString";
CFStringRef aCFString = (__bridge CFStringRef)aNSString;
NSString *bNSString = (__bridge NSString *)aCFString;
NSLog(@"the CFString : %@",aCFString);
NSLog(@"the NSString : %@",bNSString);
-6. Char 转CFString
char *cStringA = "cStringA";
CFStringRef bCFString =CFStringCreateWithCString(NULL, cStringA, kCFStringEncodingUTF8);
NSLog(@"the cfString : %@",bCFString);
-7. CFString转Char
第一种：利用CF 内置方法拿到String
//方法一 通过ssize_t
ssize_t s = CFStringGetMaximumSizeForEncoding(CFStringGetLength(bCFString), kCFStringEncodingUTF8);
char *d = malloc(s);
if(d) {
CFStringGetCString(bCFString, d, s, kCFStringEncodingUTF8);
printf("%s\n", d);
free(d);
}
//方法二 通过CFIndex
CFIndex length = CFStringGetLength(bCFString);
CFIndex maxSize = CFStringGetMaximumSizeForEncoding(length, kCFStringEncodingUTF8) + 1;
char *buffer = (char *)malloc(maxSize);
if (CFStringGetCString(bCFString, buffer, maxSize,
kCFStringEncodingUTF8)) {
printf("%s\n", buffer);
}
第二种：利用前面的关系将CFstring转成NSString再转成char
NSString *testNS = (__bridge NSString *)bCFString;
char *testC =(char *) [testNS UTF8String];
NSLog(@"-->%s",testC);
[Objective C 十六进制 十进制互转]
Mark:之前的笔记，现在挪到这边。
十六进制转十进制:
NSString *hexStr = @"0xff";
UInt64 mac1 = strtoul([hexStr UTF8String], 0, 16);
NSLog(@"%llu",mac1);
NSLog(@"十六进制转十进制 --->%lu",strtoul(hexStr.UTF8String, 0, 16));
如果有溢出的话，使用scanner：
NSString *hexStr1 = @"0x00000000027743330000000000714C9C";
unsigned long long result = 0;
NSScanner *scanner = [NSScanner scannerWithString:hexStr1];
[scanner scanHexLongLong:&result];
NSLog(@"%llu",result);
十六进制转NSString
NSString * str = @"68656C6C6F";
NSMutableString * newString = [[NSMutableString alloc] init] ;
int i = 0;
while (i < [str length])
{
NSString * hexChar = [str substringWithRange: NSMakeRange(i, 2)];
int value = 0;
sscanf([hexChar cStringUsingEncoding:NSASCIIStringEncoding], "%x", &value);
[newString appendFormat:@"%c", (char)value];
i+=2;
}
NSLog(@"new str :%@",newString);
//-->new str :hello
十进制转十六进制：
NSLog(@"十进制转十六进制 --->%@",[NSString stringWithFormat:@"%x",255]);
或者：
+(NSString *)ToHex:(long long int)tmpid
{
NSString *nLetterValue;
NSString *str =@"";
long long int ttmpig;
for (int i = 0; i<9; i++) {
ttmpig=tmpid%16;
tmpid=tmpid/16;
switch (ttmpig)
{
case 10:
nLetterValue =@"A";break;
case 11:
nLetterValue =@"B";break;
case 12:
nLetterValue =@"C";break;
case 13:
nLetterValue =@"D";break;
case 14:
nLetterValue =@"E";break;
case 15:
nLetterValue =@"F";break;
default:nLetterValue=[[NSString alloc]initWithFormat:@"%lli",ttmpig];
}
str = [nLetterValue stringByAppendingString:str];
if (tmpid == 0) {
break;
}
}
return str;
}
Knowledge, like candlelight, can illuminate a person and countless people.
