Objective-C: Reading a file line by line

Question

What is the appropriate way of dealing with large text files in Objective-C? Let's say I need to read each line separately and want to treat each line as an NSString. What is the most efficient way of doing this?

One solution is using the NSString method:

+ (id)stringWithContentsOfFile:(NSString *)path 
      encoding:(NSStringEncoding)enc 
      error:(NSError **)error 

and then split the lines with a newline separator, and then iterate over the elements in the array. However, this seems fairly inefficient. Is there no easy way to treat the file as a stream, enumerating over each line, instead of just reading it all in at once? Kinda like Java's java.io.BufferedReader.

Answer 1

This will work for general reading a String from Text. If you would like to read longer text (large size of text), then use the method that other people here were mentioned such as buffered (reserve the size of the text in memory space).

Say you read a Text File.

NSString* filePath = @""//file path...
NSString* fileRoot = [[NSBundle mainBundle] 
               pathForResource:filePath ofType:@"txt"];

You want to get rid of new line.

// read everything from text
NSString* fileContents = 
      [NSString stringWithContentsOfFile:fileRoot 
       encoding:NSUTF8StringEncoding error:nil];

// first, separate by new line
NSArray* allLinedStrings = 
      [fileContents componentsSeparatedByCharactersInSet:
      [NSCharacterSet newlineCharacterSet]];

// then break down even further 
NSString* strsInOneLine = 
      [allLinedStrings objectAtIndex:0];

// choose whatever input identity you have decided. in this case ;
NSArray* singleStrs = 
      [currentPointString componentsSeparatedByCharactersInSet:
      [NSCharacterSet characterSetWithCharactersInString:@";"]];

There you have it.