字符串base64加密、解密
//base64加密(字符串经过base64加密之后得到的新的字符串)
NSData *data = [@"iOS Developer Tips" dataUsingEncoding:NSUTF8StringEncoding];
NSString *base64Encoded = [data base64EncodedStringWithOptions:0];
//base64解密(base64加密的字符串经过base64解密之后得到的新的字符串)
NSData *nsdataDecoded = [base64Data initWithBase64EncodedString:base64Encoded options:0];
NSString *str = [[NSString alloc] initWithData:nsdataDecoded encoding:NSUTF8StringEncoding];
