Objective-C: Reading a file line by line -

-

What is the proper way to deal with large text files in Objective-C? Suppose I have to read each row separately and treat each line as an NSString. What is the most effective way to do this?

A solution is using the NSString method: 

  + (id) stringWithContentsOfFile: (NSString *) path encoding: (NSStringEncoding) Anch Error: (NSError ** ) Error

and then split the line with a new line separator, and then repeat the elements again in the array. However, it is quite inefficient. There is no easy way to treat the file as a stream, instead of just reading it at all, instead of being told in each line? Just like Java's Java.O.Buffard Reader.

This is a great question I think is a good example of @didric The answer is, though it is unfortunate that there is no mechanism for what you really want to do in Cocoa.

You have the amount of n bytes (very similar to java.io.bufferedReader ), but you can convert it to a NSString by yourself , Then Scan for Newline (or whatever other delimiter), and save any next character, or more characters to read next, if no new line has yet been read. (You can read a NSData , which you can convert to a NSString , but this is essentially the same process.)

Apple is the one who can help fill out the details, and if you are going to deal with the uint8_t * buffers, can also help.

If you want to read the wire in this way (especially in different parts of your program) it would be a good idea to explain this behavior in a class that details for you, or NSInputStream (this can sub-clinging) and by adding methods that allow you actually read what you want.

For the record, I think it will be a good feature to add, and I will file an increment request for something like that which makes it possible. : -)

Edit: This request expires already exists for a radar 2006 (for ADR-internal people (rdar: // 4742914).


Comments

Post a Comment

Popular posts from this blog

c++ - Linux and clipboard -

-
After selecting the copies of the buffer in Linux, after the text, we can click and paste the button between the mouse. I think there is a special buffer for this, I want to use it. Programming Language: C ++ Your Library: Qt Thanks. There is just one more correct answer than Paul Dixon, which answers your needs: / P > QClipboard * clipboard = QApplication :: clipboard (); CastString Selected Text = Clipboard-> Text (QClipboard :: Selection);
Read more

Visual Studio 2005: How to speed up builds when a VSMDI is open? -

-
Using Visual Studio 2005, if I open the test in VSMFI and try to run the tests, then sometimes the projects are ready. However, they run very slow. CPU 99% waste and output window VS Shows things associated with compiling it. Is there any way to fix this? It does not make any sense. It is not necessary to upgrade that we are a viable alternative to those people who have to deal with the legacy code. Did you try to upgrade SP1? I do not know of any specific problem in this area, but this will be the first change I tried to do.
Read more

booting ubuntu from usb using virtualbox -

-
I am trying to install Ubuntu on a USB, the problem is that I do not want to repeat the boot once, I want to keep my windows, but I want to boot Ubuntu using the virtualbox and USB to the Ubuntu Want to use my hard drive, but how? The virtualbox will not recognize USB as a hard drive when installing an ISO In virtualbox, you have to create a virtual hard disk. Make a USB drive and tell the virtual box to install a virtual hard drive that you just created. EDIT: To answer some more questions: In the new Virtual Disk dialog, click the button next to the location field, click on the button Virtual Disk on Flash Drive To access, click the arrow next to Save in the Select File in the window next to Save In, and you can access your flash drive from there. I recommend setting the image to be allocated dynamically, because the size of your flash drive is not available disk space. I name the image, then select that image to install Ubuntu in the Verbill box. The virtualbox will never...
Read more