How to read last n lines in a Text file in Objective C - ios

Question

I have a Text file and it has lot of lines How can i get last 'n' number of lines from the text file? and Can we give Numbers in the text file for each file How can we get it.

Answer 1

You could use NSFileHandle, seekToEndOfFile and then work backwards from the offsetInFile using seekToFileOffset: and readDataOfLength: scanning the data read each time for carriage returns and counting them until you get to the required number. As you go you can build up the text after each scan.

Answer 2

One way is putting \n to separate your different lines in the text file. Then
NSString* path = [[NSBundle mainBundle] pathForResource:#"filename"
ofType:#"txt"];
NSString* content = [NSString stringWithContentsOfFile:path
encoding:NSUTF8StringEncoding
error:NULL];
NSArray* lines = [content componentsSeparatedByString: #"\n"];
Then you can take the last few elements in the array.
Hope this helps..

Answer 3

Try to use this one:
NSString* textFile = [[NSBundle mainBundle]
pathForResource:#"fileName" ofType:#"txt"];
NSString* fileContents = [NSString stringWithContentsOfFile: textFile
encoding: NSUTF8StringEncoding error: nil];
Separate by new line
NSArray* allLinedStrings =
[fileContents componentsSeparatedByCharactersInSet:
[NSCharacterSet newlineCharacterSet]];
Here you can get your last 100 objects
NSString* oneLineStr;
for (int i = allLinedStrings.count - 100; i < allLinedStrings.count; i++)
{
oneLineStr = [allLinedStrings objectAtIndex: i];
NSLog#("New Line %#", oneLineStr);
}