Encode and Decode a string on Objective C - objective-c

Question

I use below code to encode and decode a string on objective C. The encoding is good, I debug and see that it throw a hash string when input is #"1". But when I try to decode this hash string, it return nil.
Please help me.
+(NSString *)encrypt: (NSString*) input
{
//Base64 Encoding
char base64Result[32];
size_t theResultLength = 32;
Base64EncodeData(input, 20, base64Result, &theResultLength);
NSData *theData = [NSData dataWithBytes:base64Result length:theResultLength];
NSString *base64EncodedResult = [[NSString alloc] initWithData:theData encoding:NSUTF8StringEncoding];
NSString* decryptedString = [self decrypt:base64EncodedResult];
return [base64EncodedResult autorelease];
}
+ (NSString *) decrypt:(NSString*) input{
Byte inputData[[input lengthOfBytesUsingEncoding:NSUTF8StringEncoding]];//prepare a Byte[]
[[input dataUsingEncoding:NSUTF8StringEncoding] getBytes:inputData];//get the pointer of the data
size_t inputDataSize = (size_t)[input length];
size_t outputDataSize = EstimateBas64DecodedDataSize(inputDataSize);//calculate the decoded data size
Byte outputData[outputDataSize];//prepare a Byte[] for the decoded data
Base64DecodeData(inputData, inputDataSize, outputData, &outputDataSize);//decode the data
NSData *theData = [[NSData alloc] initWithBytes:outputData length:outputDataSize];//create a NSData object from the decoded data
NSString *result = [[NSString alloc] initWithData:theData encoding:NSUTF8StringEncoding];
return [result autorelease];
}

Answer 1

In you encoding method, you have to convert the input string to a byte buffer and feed that to Base64EncodeData:
NSData *inputData = [input dataUsingEncoding:NSUTF8StringEncoding];
Base64EncodeData([inputData bytes], [inputData length], base64Result, &theResultLength, NO);
(The NSString *input argument in the encoding method points to an Objective-C structure, not to a C string. So your encoding method seems to work. It encodes something, but not the input string. The decoding method then fails at
NSString *result = [[NSString alloc] initWithData:theData encoding:NSUTF8StringEncoding];
because the decoded data does not contain valid UTF-8.)