Question

I have a C string, it is encoded with UTF-7, like "+g0l6P3ux-".

I can decode the string with Python. But when I use:

[NSString stringWithCString:"+g0l6P3ux-" encoding:kCFStringEncodingUTF7];

it returns nil, why ?

Answer 1

The function you use

+ (id)stringWithCString:(const char *)cString encoding:(NSStringEncoding)enc

expects NSStringEncoding, and if you look up NSStringEncoding in the docs, kCFStringEncodingUTF7 is not a valid value.

Instead of

NSString *str = [NSString stringWithCString:"+g0l6P3ux-" encoding:kCFStringEncodingUTF7];

you could use

CFStringRef cfstr = CFStringCreateWithCString(NULL, "+g0l6P3ux-", kCFStringEncodingUTF7);
NSString *str = [(NSString *)cfstr copy];
CFRelease(cfstr);