CODEWITHSUNDEEP
iosobjective-cnsfilemanagernsfilehandle
Naresh G
Naresh G

Reputation: 117

How to write data in chunks into disk in ios

Hi in my app I am downloading a pdf file and that total size i am getting in chunks. Now after i get that data in chunks I am storing in NSData object and remaining chunks I am appending to the same object. while doing this app is getting crash with low memory warning. Is there any way to write data to disk next onwards append data to written file in sandbox. Sometime file is more than 400 Mb.Please help me.

Upvotes: 1

Views: 1455

Answers (2)

user523234
user523234

Reputation: 14834

NSFileHandle can be used for this:

Something like this:

Step1: Create an iVar called _outputFileHandle;

NSFileHandle *_outputFileHandle;

Step2: Calling the prepareDataHandle once:

Step3: Calling writingDataToFile whenever data junk is coming in.

Modify your work flow accordingly so it can tell when file downloading is completed.

-(void)prepareDataHandle
{
    NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *outputFilePath = [documentsDirectory stringByAppendingPathComponent:@"anoutputfile.xxx"];
     if ([[NSFileManager defaultManager] fileExistsAtPath:outputFilePath] == NO)
    {
        NSLog(@"Create the new file at outputFilePath: %@", outputFilePath);
        BOOL suc = [[NSFileManager defaultManager] createFileAtPath:outputFilePath
                                              contents:nil
                                            attributes:nil];
        NSLog(@"Create file successful?: %u", suc);
    }
    _outputFileHandle = [NSFileHandle fileHandleForWritingAtPath:outputFilePath];
}

-(void)writingDataToFile:(NSData *)dataToWrite
{
    if (dataToWrite.length != 0)
    {
        [_outputFileHandle writeData:dataToWrite];
    }
    else   //you can use dataToWrite with length of 0 to indicate the end of downloading or come up with some unique sequence yourself
    {
        NSLog(@"Finished writing... close file");
        [_outputFileHandle closeFile];
    }
}

Upvotes: 3

Flexicoder
Flexicoder

Reputation: 8501

You can use an NSOutputStream

https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/Streams/Articles/WritingOutputStreams.html

Upvotes: 0

Related Questions