Class to enumerate over the contents of a file handle line-by-line

TsLineEnumerator.h

//
//  TsLineEnumerator.h
//  Typesetter
//
//  Created by Brent Royal-Gordon on 2/3/12.
//  Copyright (c) 2012 Architechies. All rights reserved.
//

@interface NSFileHandle (lineEnumerator)
- (NSEnumerator*)lineEnumerator;
@end

@interface TsLineEnumerator : NSEnumerator

- (id)initWithReadingFileHandle:(NSFileHandle*)fh;

@end

TsLineEnumerator.m

//
//  TsLineEnumerator.m
//  Typesetter
//
//  Created by Brent Royal-Gordon on 2/3/12.
//  Copyright (c) 2012 Architechies. All rights reserved.
//

#import "TsLineEnumerator.h"

@implementation NSFileHandle (lineEnumerator)

- (NSEnumerator *)lineEnumerator {
    return [[TsLineEnumerator alloc] initWithReadingFileHandle:self];
}

@end

@interface TsLineEnumerator ()

@property (strong) NSFileHandle * fileHandle;
@property (strong) NSMutableString * buffer;

@end

@implementation TsLineEnumerator

- (id)initWithReadingFileHandle:(NSFileHandle *)fh {
    if((self = [super init])) {
        self.fileHandle = fh;
        self.buffer = [NSMutableString new];
    }
    return self;
}

- (id)nextObject {
    if(self.buffer == nil) {
        return nil;
    }
    
    NSRange lineBreakRange = [self.buffer rangeOfString:@"\n"];
    
    if(lineBreakRange.location != NSNotFound) {
        NSRange lineRange = NSMakeRange(0, lineBreakRange.location + lineBreakRange.length);
        NSString * line = [self.buffer substringWithRange:lineRange];
        [self.buffer deleteCharactersInRange:lineRange];
        return line;
    }
    
    // We don't have a line...
    NSData * data = [self.fileHandle availableData];
    if(data.length == 0) {
        // End of file--we'll have to return the buffer as the last line.
        NSString * line = self.buffer.copy;
        self.buffer = nil;  // mark it as EOF
        return line;
    }
    
    // Append the data to the buffer...
    [self.buffer appendString:[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]];
    // ...and try it all again.
    return [self nextObject];
}

@synthesize fileHandle;
@synthesize buffer;

@end