How to convert NSData to NSString in Japanese

Question

When I convert NSString to NSData, after convert from NSData to NSString

NSString *input = @"ステータス";
NSData *output = [NSData dataWithBytes:[input UTF8String] length:[input length]];
NSString *output2 = [[NSString alloc] initWithData:output encoding:NSUTF8StringEncoding];

The output2 is nil.
If input is alphabet character, it ok.

Answer 1

The correct conversion is

NSData* output = [input dataUsingEncoding:NSUTF8StringEncoding];

The problem with your code is that [input length] gives the number of Unicode characters, not the number of UTF-8 bytes.