iOS Base64轉碼（使用ios7系統自帶編碼庫 和 GMTBase64 兩種方式）

示例如下：

    nsdata* origindata = [originstr

datausingencoding:nsasciistringencoding];

    nsstring* encoderesult = [origindata

base64encodedstringwithoptions:nsdatabase64encodingendlinewithlinefeed];

    nslog(@"encoderesult:%@",encoderesult);

    nsdata* decodedata = [[nsdata

alloc] initwithbase64encodedstring:encoderesult

options:0];

    nsstring* decodestr = [[nsstring

alloc] initwithdata:decodedata

encoding:nsasciistringencoding];

/**

 *gtm 轉碼

 */

-(void)gtmencodetest

{

    nsstring* originstr =

@"man";

    nsstring* encoderesult =

nil;

    nsdata* origindata = [originstr

datausingencoding:nsutf8stringencoding];

    nsdata* encodedata = [gtmbase64

encodedata:origindata];

    encoderesult = [[nsstring

alloc] initwithdata:encodedata

encoding:nsutf8stringencoding];

    nslog(@"%@",encoderesult);

}

 * gtm 解碼

-(void)gmtdecodetest

    nsstring* encodestr =

@"twfu";

    nsstring* decoderesult =

    nsdata* encodedata = [encodestr

    nsdata* decodedata = [gtmbase64

decodedata:encodedata];

    decoderesult = [[nsstring

    nslog(@"%@",decoderesult);