字符串，base64加密

NSData *nsdata = [@"iOS Developer Tips encoded in Base64"

dataUsingEncoding:NSUTF8StringEncoding];

NSString *base64Encoded = [NSData base64EncodedStringWithOptions:0];

NSLog(@"Encoded: %@", base64Encoded);

字符串，base64解密

NSData *nsdataFromBase64String = [[NSData alloc]

initWithBase64EncodedString:base64Encoded options:0];

NSString *base64Decoded = [[NSString alloc]

initWithData:nsdataFromBase64String encoding:NSUTF8StringEncoding];

NSLog(@"Decoded: %@", base64Decoded);