How to remove tmp directory files of an ios app?

Yes. This method works well:

+ (void)clearTmpDirectory
{
    NSArray* tmpDirectory = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:NSTemporaryDirectory() error:NULL];
    for (NSString *file in tmpDirectory) {
        [[NSFileManager defaultManager] removeItemAtPath:[NSString stringWithFormat:@"%@%@", NSTemporaryDirectory(), file] error:NULL];
    }
}