Objective-C stream file lines with NSInputStream

#import <Foundation/Foundation.h>

static void ReadLines(NSString *path, void (^onLine)(NSString *)) {
    NSInputStream *in = [NSInputStream inputStreamWithFileAtPath:path];
    [in open];
    uint8_t buf[4096];
    NSMutableData *pending = [NSMutableData data];
    NSData *nl = [NSData dataWithBytes:(uint8_t[]){10} length:1];
    NSInteger n = 0;
    while ((n = [in read:buf maxLength:sizeof buf]) > 0) {
        [pending appendBytes:buf length:(NSUInteger)n];
        NSRange r;
        while ((r = [pending rangeOfData:nl options:0 range:NSMakeRange(0, pending.length)]).location != NSNotFound) {
            NSString *line = [[NSString alloc] initWithData:[pending subdataWithRange:NSMakeRange(0, r.location)] encoding:NSUTF8StringEncoding];
            if (line) onLine(line);
            [pending replaceBytesInRange:NSMakeRange(0, r.location + r.length) withBytes:NULL length:0];
        }
    }
    [in close];
    if (pending.length > 0) onLine([[NSString alloc] initWithData:pending encoding:NSUTF8StringEncoding] ?: @"");
}