Find a substring in NSMutableArray of string fast

Question

I have an array like

NSMutableArray *arr = [NSMutableArray arrayWithObjects:@"How many degrees ", @"Which club degree", @"body building", nil];

A want to filter only those string contains degree. I am using old IOS, i don't have [string stringcontains] method

The required Array must have -> 1. How many degrees 2. Which club degree

First Method I use

NSString *strToMatch=@"degree";

    for (NSString *description in arr)
    {
     NSComparisonResult result = [description compare:strToMatch options:(NSCaseInsensitiveSearch|NSDiacriticInsensitiveSearch) range:NSMakeRange(0, [strToMatch length])];

           if (result == NSOrderedSame)
              {
                 // statement to run on comparison succeeded..
              }
    }

Second Method

for (NSString *description in arr)
   {

      if ([description rangeOfString:strToMatch options:NSCaseInsensitiveSearch].location != NSNotFound)
        {
            NSLog(@"I am matched....");
        }
  }

It is working fine. I have shown you the code to compare a single string but i have to compare this array with another array of string. I want to speed up my code. Is there any other better approach to find it.

And how can we create a NSPredicate to compare two array of string. Find first arrray of string as a substring in second array.

And which approach is fast.

Thanks in Advance.

l0gg3r · Accepted Answer · 2014-10-30 10:21:23Z

3

You can use NSPredicate and -[NSArray filteredArrayUsingPredicate:] as it's available from iOS 3.0

NSMutableArray *arr = [NSMutableArray arrayWithObjects:@"How many degrees ", @"Which club degree", @"body building", nil];
NSString *searchText = @"degree";
NSArray *filtered = [arr filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"self contains %@", searchText]];

Also for case-insensitive and diacritic-insensitive search use

NSMutableArray *arr = [NSMutableArray arrayWithObjects:@"How many degrees ", @"Which club degree", @"body building", nil];
NSString *searchText = @"deGree";
NSArray *filtered = [arr filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"self contains[cd] %@", searchText]];

If you want to search array of keywords in another array, you can use NSCompoundPredicate which is also available from iOS 3.0.

NSMutableArray *arr = [NSMutableArray arrayWithObjects:@"How many degrees ", @"Which club degree", @"body building", @"hello world" , nil];
NSArray *keywordsToSearch = @[@"deGree", @"world"];
NSMutableArray *predicates = [NSMutableArray new];
for (NSString *keyword in keywordsToSearch) {
    [predicates addObject:[NSPredicate predicateWithFormat:@"self contains[cd] %@", keyword]];
}
NSPredicate *wholePredicate = [NSCompoundPredicate orPredicateWithSubpredicates:predicates];

NSArray *filtered = [arr filteredArrayUsingPredicate:wholePredicate];

Also you can check performance and choose the best one.

NSTimeInterval startTime = [[NSDate date] timeIntervalSince1970];
// .... here searching code
NSTimeInterval endTime = [[NSDate date] timeIntervalSince1970];
NSLog(@"Duration %f", endTime - startTime);

edited Oct 30, 2014 at 10:21

answered Oct 30, 2014 at 7:27

l0gg3r

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4 Comments

Zar E Ahmer Over a year ago

running perfectly but tell me which method is fast and when to chose between NSPredicate or my way..

l0gg3r Over a year ago

I think Apple's implementation should be faster, but anyway I have added performance code, check me edit.

Zar E Ahmer Over a year ago

Thanks,I am new to IOS, can you suggest me some sites or tutorial through which i can enhance my concepts about IOS. Not code.I want to learn concepts .

l0gg3r Over a year ago

I think WWDC videos can be very helpful (especially 'Advanced' videos) developer.apple.com/videos/wwdc/2014 also you can check developer.apple.com/library/ios/navigation

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