Simple class that takes an input stream and writes it to a file by streaming. Duh.

LBCStreamWriter.h

//
//  LBCStreamWriter.h
//  LBCCore
//
//  Created by Jeremy Foo on 23/5/12.
//  Copyright (c) 2012 BOB FTW PTE LTD. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#import <Foundation/Foundation.h>

typedef void (^LBCStreamWriterCompletionHandler)(BOOL hasError, NSError *error);

typedef enum {
    LBCStreamWriterOutputFileAlreadyExistsError
    
} LBCStreamWriterErrorStatus;

extern NSString *const LBCStreamWriterErrorDomain;

@interface LBCStreamWriter : NSObject <NSStreamDelegate>
@property (readonly) NSInputStream *inputStream;
@property (nonatomic, copy) NSURL *outputFileURL;

+(void)stream:(NSInputStream *)input toDestinationFileURL:(NSURL *)url completion:(LBCStreamWriterCompletionHandler)completion;

-(id)initWithInputStream:(NSInputStream *)input destinationFileURL:(NSURL *)url;
-(void)performStreamWithCompletion:(LBCStreamWriterCompletionHandler)completion;

@end

LBCStreamWriter.m

//
//  LBCStreamWriter.m
//  LBCCore
//
//  Created by Jeremy Foo on 23/5/12.
//  Copyright (c) 2012 BOB FTW PTE LTD. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#import "LBCStreamWriter.h"

NSString *const LBCStreamWriterErrorDomain = @"LBCStreamWriterErrorDomain";

@interface LBCStreamWriter (/* Private Method */)
@property (nonatomic, copy) LBCStreamWriterCompletionHandler _completion;
@property (nonatomic, retain) NSOutputStream *_outputStream;
@end

@implementation LBCStreamWriter
@synthesize inputStream = _inputStream, outputFileURL = _outputFileURL;
@synthesize _completion, _outputStream;

#pragma mark - Object Life Cycle

+(void)stream:(NSInputStream *)input toDestinationFileURL:(NSURL *)url completion:(LBCStreamWriterCompletionHandler)completion {
    LBCStreamWriter *writer = [[LBCStreamWriter alloc] initWithInputStream:input destinationFileURL:url];
    [writer performStreamWithCompletion:completion];
    [writer release];
}

-(id)initWithInputStream:(NSInputStream *)input destinationFileURL:(NSURL *)url {
    if ((self = [super init])) {
        _inputStream = [input retain];
        self.outputFileURL = url;
    }
    
    return self;
}

-(void)dealloc {
    [_inputStream release], _inputStream = nil;
    [_outputFileURL release], _outputFileURL = nil;
    [_completion release], _completion = nil;
    [_outputStream release], _outputStream = nil;
    [super dealloc];
}

#pragma mark - Stream Writer

-(void)performStreamWithCompletion:(LBCStreamWriterCompletionHandler)completion {
    NSAssert1([_outputFileURL isFileURL], @"Please use a file URL for the destination file", nil);
    NSAssert1(_inputStream != nil, @"Input stream must exist for this to even work properly", nil);
    
    if ([[NSFileManager defaultManager] fileExistsAtPath:[_outputFileURL path]]) {
        if (completion)
            completion(YES, [NSError errorWithDomain:LBCStreamWriterErrorDomain code:LBCStreamWriterOutputFileAlreadyExistsError userInfo:nil]);
                       
        return;
    }
    
    self._completion = completion;
    
    self.inputStream.delegate = self;
    [self.inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    
    self._outputStream = [NSOutputStream outputStreamToFileAtPath:[self.outputFileURL path] append:NO];
    [self._outputStream open];
    
    [self retain];
        
}

#pragma mark - NSStreamDelegate

-(void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode {
    if (aStream == self.inputStream) {
        uint8_t buf[1024*100];
        NSUInteger len = 0;
        switch(eventCode) {
            case NSStreamEventOpenCompleted:
                // Media file open
                break;
            case NSStreamEventHasBytesAvailable:
                len = [self.inputStream read:buf maxLength:1024];
                if (len) {
                    [self._outputStream write:buf maxLength:len];
                    
                } else {

                    if (_completion)
                        _completion(NO, nil);

                    [self release];
                }
                break;
            case NSStreamEventErrorOccurred:
                if (_completion)
                    _completion(YES, [aStream streamError]);
                
                [self release];
                
                break;
            default:
                // Unhandled Stream event
                break;
        }
    }
}

@end