IOS编码转化

原文地址：http://blog.csdn.net/huifeidexin_1/article/details/7883984

iOS中编码转化

1.UTF-8转化

NSString *data = @"你好，北京！";

//转换成UTF-8

NSString *dataUTF8 = [datastringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSLog(@"%@",dataUTF8);

//UTF-8转GBK,将UTF8代码替换，官方解释如下。

//Replaces all percent escapes with the matching characters as determined by the given encoding.  Returns nil if the transformation is not possible (i.e. the percent escapes give a byte sequence not legal in the given encoding).  See CFURLCreateStringByReplacingPercentEscapes in CFURL.h for more complex transformations

NSString *dataGBK = [dataUTF8stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSLog(@"%@",dataGBK);

在Xcode4.2中执行结果如下：

将上述方法封装，如下：

//Unicode转UTF-8

+ (NSString *)encodeToPercentEscapeString: (NSString *) input

{

// Encode all the reserved characters, per RFC 3986

// (<http://www.ietf.org/rfc/rfc3986.txt>)

NSString *outputStr = (NSString *)

CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,

(CFStringRef)input,

NULL,

(CFStringRef)@"!*'();:@&=+$,/?%#[]",

kCFStringEncodingUTF8);

return outputStr;

}

+ (NSString *)decodeFromPercentEscapeString: (NSString *) input

{

NSMutableString *outputStr = [NSMutableStringstringWithString:input];

[outputStr replaceOccurrencesOfString:@"+"

withString:@" "

options:NSLiteralSearch

range:NSMakeRange(0, [outputStrlength])];

return [outputStrstringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

}

2.UTF-8和Unicode转化

//Unicode转UTF-8

+ (NSString*) replaceUnicode:(NSString*)aUnicodeString

{

NSString *tempStr1 = [aUnicodeStringstringByReplacingOccurrencesOfString:@"\\u"withString:@"\\U"];

NSString *tempStr2 = [tempStr1stringByReplacingOccurrencesOfString:@"\""withString:@"\\\""];

NSString *tempStr3 = [[@"\""stringByAppendingString:tempStr2] stringByAppendingString:@"\""];

NSData *tempData = [tempStr3dataUsingEncoding:NSUTF8StringEncoding];

NSString* returnStr = [NSPropertyListSerializationpropertyListFromData:tempData

mutabilityOption:NSPropertyListImmutable

format:NULL

errorDescription:NULL];

return [returnStrstringByReplacingOccurrencesOfString:@"\\r\\n"withString:@"\n"];

}

+(NSString *) utf8ToUnicode:(NSString *)string

{

NSUInteger length = [string length];

NSMutableString *s = [NSMutableStringstringWithCapacity:0];

for (int i = 0;i < length; i++)

{

unichar _char = [string characterAtIndex:i];

//判断是否为英文和数字

if (_char <= '9' && _char >='0')

{

[s appendFormat:@"%@",[stringsubstringWithRange:NSMakeRange(i,1)]];

}

else if(_char >='a' && _char <= 'z')

{

[s appendFormat:@"%@",[stringsubstringWithRange:NSMakeRange(i,1)]];

}

else if(_char >='A' && _char <= 'Z')

{

[s appendFormat:@"%@",[stringsubstringWithRange:NSMakeRange(i,1)]];

}

else

{

[s appendFormat:@"\\u%x",[stringcharacterAtIndex:i]];

}

}

return s;

}