create a directory in the iPhone

Question

What's wrong with that?

#define AUDIO_NOTES_FOLDER [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/myApp/Pictures"]

NSFileManager *NSFm= [NSFileManager defaultManager]; 
BOOL isDir=YES;

if(![NSFm fileExistsAtPath:FILEPATH isDirectory:&isDir])
    if(![NSFm createDirectoryAtPath:FILEPATH attributes:nil])
        NSLog(@"Error: Create folder failed");

Answer 1

The FILEPATH token is undefined - you #define AUDIO_NOTES_FOLDER at the beginning of your file, then use FILEPATH instead in your code.

Also note that NSHomeDirectory() isn't necessarily the recommended way of finding the Documents directory anymore - instead you probably want:

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];

Answer 2

createDirectoryAtPath:attributes: is deprecated, instead you should use:

    NSString *dirToCreate = [NSString stringWithFormat:@"%@/newDirectory",[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject]];
    NSError *error = nil;
    BOOL isDir;
    if(![fm fileExistsAtPath:dirToCreate isDirectory:&isDir])
        if(![fm createDirectoryAtPath:dirToCreate withIntermediateDirectories:YES attributes:nil error:&error])
            NSLog(@"Error: Create folder failed");