iOS中編碼轉化

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

iOS中編碼轉化

1.UTF-8轉化

 

    NSString *data = @"你好，北京！";

    //轉換成UTF-8

    NSString *dataUTF8 = [datastringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

    NSLog(@"%@",dataUTF8);

    //UTF-8轉GBK,將UTF8代碼替換，官方解釋如下。

//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中執行結果如下：

將上述方法封裝，如下：

 

//Unicode轉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轉化

 

//Unicode轉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];

        //判斷是否為英文和數字

        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;

}

 

by:panguo