我想进行base64编码和解码,但我无法从iPhone SDK中找到任何支持。我怎么能做base64编码和解码与或没有一个库?
当前回答
很高兴人们喜欢它。我必须承认,最后的游戏有点瑕疵。除了正确地设置inp=0之外,您还应该将tmpbuf的大小增加到3
unsigned char tmpbuf[3] = {0,0,0};
或者省略raw[inp+2]的环;如果我们对这个块有一个原始的[inp+2] != 0,当然我们仍然在循环中……
无论哪种方法都可行,为了清晰起见,您可以考虑保持最终的表查找块与循环中的表查找块相同。在最后的版本中,我使用了
while ( outp%4 ) outbuf[outp++] = '=';
添加==
对不起,我没有检查RFC之类的东西,应该做得更好!
其他回答
这是一个紧凑的Objective-C版本,作为NSData的类别。这需要一些思考……
@implementation NSData (DataUtils)
static char base64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
- (NSString *)newStringInBase64FromData
{
NSMutableString *dest = [[NSMutableString alloc] initWithString:@""];
unsigned char * working = (unsigned char *)[self bytes];
int srcLen = [self length];
// tackle the source in 3's as conveniently 4 Base64 nibbles fit into 3 bytes
for (int i=0; i<srcLen; i += 3)
{
// for each output nibble
for (int nib=0; nib<4; nib++)
{
// nibble:nib from char:byt
int byt = (nib == 0)?0:nib-1;
int ix = (nib+1)*2;
if (i+byt >= srcLen) break;
// extract the top bits of the nibble, if valid
unsigned char curr = ((working[i+byt] << (8-ix)) & 0x3F);
// extract the bottom bits of the nibble, if valid
if (i+nib < srcLen) curr |= ((working[i+nib] >> ix) & 0x3F);
[dest appendFormat:@"%c", base64[curr]];
}
}
return dest;
}
@end
如果需要,可以通过扩大'byt'的范围并在(2-byt)后面附加'dest'来添加填充。返回前的"="字符。
Category可以被添加到NSString中,这样:
@implementation NSString (StringUtils)
- (NSString *)newStringInBase64FromString
{
NSData *theData = [NSData dataWithBytes:[self UTF8String] length:[self length]];
return [theData newStringInBase64FromData];
}
@end
下面是一个将NSData对象转换为base64的例子。它还展示了如何以另一种方式(解码一个base64编码的NSData对象):
NSData *dataTake2 =
[@"iOS Developer Tips" dataUsingEncoding:NSUTF8StringEncoding];
// Convert to Base64 data
NSData *base64Data = [dataTake2 base64EncodedDataWithOptions:0];
// Do something with the data...
// Now convert back from Base64
NSData *nsdataDecoded = [base64Data initWithBase64EncodedData:base64Data options:0];
下载Base64
做以下代码转换图像到base64
NSString *base64String=[UIImagePNGRepresentation(image) base64Encoding];
这是Objective C类别的一个很好的用例。
对于Base64编码:
#import <Foundation/NSString.h>
@interface NSString (NSStringAdditions)
+ (NSString *) base64StringFromData:(NSData *)data length:(int)length;
@end
-------------------------------------------
#import "NSStringAdditions.h"
static char base64EncodingTable[64] = {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
};
@implementation NSString (NSStringAdditions)
+ (NSString *) base64StringFromData: (NSData *)data length: (int)length {
unsigned long ixtext, lentext;
long ctremaining;
unsigned char input[3], output[4];
short i, charsonline = 0, ctcopy;
const unsigned char *raw;
NSMutableString *result;
lentext = [data length];
if (lentext < 1)
return @"";
result = [NSMutableString stringWithCapacity: lentext];
raw = [data bytes];
ixtext = 0;
while (true) {
ctremaining = lentext - ixtext;
if (ctremaining <= 0)
break;
for (i = 0; i < 3; i++) {
unsigned long ix = ixtext + i;
if (ix < lentext)
input[i] = raw[ix];
else
input[i] = 0;
}
output[0] = (input[0] & 0xFC) >> 2;
output[1] = ((input[0] & 0x03) << 4) | ((input[1] & 0xF0) >> 4);
output[2] = ((input[1] & 0x0F) << 2) | ((input[2] & 0xC0) >> 6);
output[3] = input[2] & 0x3F;
ctcopy = 4;
switch (ctremaining) {
case 1:
ctcopy = 2;
break;
case 2:
ctcopy = 3;
break;
}
for (i = 0; i < ctcopy; i++)
[result appendString: [NSString stringWithFormat: @"%c", base64EncodingTable[output[i]]]];
for (i = ctcopy; i < 4; i++)
[result appendString: @"="];
ixtext += 3;
charsonline += 4;
if ((length > 0) && (charsonline >= length))
charsonline = 0;
}
return result;
}
@end
对于Base64解码:
#import <Foundation/Foundation.h>
@class NSString;
@interface NSData (NSDataAdditions)
+ (NSData *) base64DataFromString:(NSString *)string;
@end
-------------------------------------------
#import "NSDataAdditions.h"
@implementation NSData (NSDataAdditions)
+ (NSData *)base64DataFromString: (NSString *)string
{
unsigned long ixtext, lentext;
unsigned char ch, inbuf[4], outbuf[3];
short i, ixinbuf;
Boolean flignore, flendtext = false;
const unsigned char *tempcstring;
NSMutableData *theData;
if (string == nil)
{
return [NSData data];
}
ixtext = 0;
tempcstring = (const unsigned char *)[string UTF8String];
lentext = [string length];
theData = [NSMutableData dataWithCapacity: lentext];
ixinbuf = 0;
while (true)
{
if (ixtext >= lentext)
{
break;
}
ch = tempcstring [ixtext++];
flignore = false;
if ((ch >= 'A') && (ch <= 'Z'))
{
ch = ch - 'A';
}
else if ((ch >= 'a') && (ch <= 'z'))
{
ch = ch - 'a' + 26;
}
else if ((ch >= '0') && (ch <= '9'))
{
ch = ch - '0' + 52;
}
else if (ch == '+')
{
ch = 62;
}
else if (ch == '=')
{
flendtext = true;
}
else if (ch == '/')
{
ch = 63;
}
else
{
flignore = true;
}
if (!flignore)
{
short ctcharsinbuf = 3;
Boolean flbreak = false;
if (flendtext)
{
if (ixinbuf == 0)
{
break;
}
if ((ixinbuf == 1) || (ixinbuf == 2))
{
ctcharsinbuf = 1;
}
else
{
ctcharsinbuf = 2;
}
ixinbuf = 3;
flbreak = true;
}
inbuf [ixinbuf++] = ch;
if (ixinbuf == 4)
{
ixinbuf = 0;
outbuf[0] = (inbuf[0] << 2) | ((inbuf[1] & 0x30) >> 4);
outbuf[1] = ((inbuf[1] & 0x0F) << 4) | ((inbuf[2] & 0x3C) >> 2);
outbuf[2] = ((inbuf[2] & 0x03) << 6) | (inbuf[3] & 0x3F);
for (i = 0; i < ctcharsinbuf; i++)
{
[theData appendBytes: &outbuf[i] length: 1];
}
}
if (flbreak)
{
break;
}
}
}
return theData;
}
@end
我想这会有帮助的
+ (NSString *)toBase64String:(NSString *)string {
NSData *data = [string dataUsingEncoding: NSUnicodeStringEncoding];
NSString *ret = [data base64EncodedStringWithOptions:NSDataBase64Encoding64CharacterLineLength];
return ret;
}
+ (NSString *)fromBase64String:(NSString *)string {
NSData *aData = [string dataUsingEncoding:NSUTF8StringEncoding];
NSData *aDataDecoded = [[NSData alloc]initWithBase64EncodedString:string options:0];
NSString *decryptedStr = [[NSString alloc]initWithData:aDataDecoded encoding:NSUTF8StringEncoding];
return [decryptedStr autorelease];
}
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