scanning NSMutableArray for part of a string

Question

Im new to iphone programming and im kinda stuck with my current project. I got a text file with a lot of data in it. Data is sorted like this:

51398030 10003254 80211593/94     1301281744 TOMTOM100  
51398030 10003254 80211593/94     1301281744 TOMTOM101  
51398030 10003254 80211593/94     1301281745 TOMTOM102  
51398030 10003254 80211593/94     1301281745 TOMTOM103  
51398033 10003254 80211595        1301281744 TOMTOM100  
51398033 10003254 80211595        1301281744 TOMTOM101  
51398033 10003254 80211595        1301281745 TOMTOM102  
51398033 10003254 80211595        1301281745 TOMTOM103  
51398029 10003254 80211597/98     1301281744 TOMTOM100  
51398029 10003254 80211597/98     1301281744 TOMTOM101  
51398029 10003254 80211597/98     1301281745 TOMTOM102  
51398029 10003254 80211597/98     1301281745 TOMTOM103

I already imported this txt file and created a NSMutableArray that contains each line as object. Now i have a textfield where the user can enter a number. the app should now look trough the text file and and sort out the lines containing this number.

I already looked at https://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/Strings/Articles/Scanners.html#//apple_ref/doc/uid/20000147-BCIEFGHC

but i dont know how to start.

This is how far i got:

    NSData *tmpData = [NSData dataWithContentsOfURL:[NSURL       URLWithString:trackTraceFileUrlName] ];
    NSLog(@"%@",trackTraceFileUrlName);
    //convert data to string 
    NSString *tmpString = [[NSString alloc] initWithData:tmpData              encoding:NSUTF8StringEncoding];
    NSArray *piecesArray = [tmpString componentsSeparatedByString:@"\n"];
    NSMutableArray *trackTraceContent = [NSMutableArray arrayWithArray:piecesArray];
    NSLog(@"*%@*",trackTraceContent);

Answer 1

Try the below code

NSString *str = <string on which you want to search>;

    NSRange r;
    if ((r = [str rangeOfString:@"the string you want to search"]).location != NSNotFound)
        //string found..

I think you have an array so try the modified one

for (NSString *str in <array>)
{
    NSRange r;
    if ((r = [str rangeOfString:@"the string you want to search"]).location != NSNotFound)
        //string found..
}

Answer 2

Since you probably want to search over all the lines in the array, and assuming that you array just contains the strings as NSString objects:

NSArray *stringArray; // assuming that you already have these variables
NSString *numberEnteredByUser;
NSPredicate *pred = [NSPredicate predicateWithBlock:^(id obj, NSDictionary *bindings) {
    NSString *str = (NSString *)obj;
    return [str rangeOfString:numberEnteredByUser].location != NSNotFound;
}];
NSArray *results = [stringArray filteredArrayUsingPredicate:pred];

Of course, you can also create the target array without using NSPredicate, by just iterating over stringArray and adding the right objects to a NSMutableArray results .

Answer 3

If the number entered by the user is the primary search into your data, and it's unique , then hold your data in a dictionary, not an array, using the number as the key:

NSMutableDictionary *dictionary = [[NSMutableDictionary alloc] init];
MyObject obj = ...;
[dictionary setObject:obj forKey:obj.number];
// etc.

Look-up will be much faster, as this is precisely what dictionaries (hash tables) are for.

Note: Objective-C collection classes can only hold objects, so you will need to represent the number using an NSNumber object, not a primitive type.

If the number is not unique then you can still use this technique, but you'll need to hold a dictionary of arrays, using the number as the key into that array, which complicates things somewhat. However you will still gain performance benefit doing this.