Objective-C removing whitespace from strings in array - objective-c

Question

I want to import a file of strings line by line into an array. I want to get rid of all of the whitespace before and after the strings so that I can compare the strings a lot easier without having them not match due to small whitespace discrepancies. I NSData the content of the files then take the two strings
NSString* string = [[[NSString alloc] initWithBytes:[data bytes]
length:[data length]
encoding:NSUTF8StringEncoding] autorelease];
NSString* string2 = [[[NSString alloc] initWithBytes:[data2 bytes]
length:[data2 length]
encoding:NSUTF8StringEncoding] autorelease];
I tried below to remove the whitespace before adding to an array but it does not seem to work.
NSString *newString = [string stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceCharacterSet]];
NSString *newString2 = [string2 stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceCharacterSet]];
NSArray *fileInput = [newString componentsSeparatedByString:#"\n"];
NSArray *fileInput2 = [newString2 componentsSeparatedByString:#"\n"];

Answer 1

If you are looking at substituting all occurrences of whitespace then using stringByTrimmingCharactersInSet: won't help as it only trims off at the start and end of the string. You will need to use the stringByReplacingOccurrencesOfString:withString: method to eliminate the whitespace.
NSString * newString = [string stringByReplacingOccurrencesOfString:#" " withString:#""];
NSString * newString2 = [string2 stringByReplacingOccurrencesOfString:#" " withString:#""];
However,
If you want to trim all the strings in the array then you will have to enumerate the array and add the trimmed strings in a new mutable array.

Answer 2

Looks to me like you are removing the white space from the front and back of the whole file but not from each line. Try something like this;
NSArray *fileInput2 = [newString2 componentsSeparatedByString:#"\n"];
NSMutableArray *trimmedFileInput2 = [NSMutableArray array];
for(NSString *gak in fileInput2) {
[trimmedFileInput2 addObject:[gak stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
}
[Thanks #Deepak for the comment, dooh!]

Answer 3

Both #Deepak and #Bill Dudney being right, I'm just throwing in another way to solve your problem:
NSMutableArray *fileInput = [NSMutableArray array];
[string enumerateLinesUsingBlock:^(NSString *line, BOOL *stop) {
if ([line length] > 0) {
[fileInput addObject:
[line stringByTrimmingCharactersInSet:
[NSCharacterSet whitespaceCharacterSet]];
}
}];
(Disclaimer: Works in iOS 4+, OS X 10.6+ only... but I love blocks! :))