Number of occurrences of a substring in an NSString?

objective-c cocoa nsstring substring
igul222 picture igul222 · Jan 30, 2010 · Viewed 53.5k times · Source

How can I get the number of times an NSString (for example, @"cake") appears in a larger NSString (for example, @"Cheesecake, apple cake, and cherry pie")?

I need to do this on a lot of strings, so whatever method I use would need to be relatively fast.

Thanks!

Answer

Matthew Flaschen picture Matthew Flaschen · Jan 30, 2010

This isn't tested, but should be a good start.

NSUInteger count = 0, length = [str length];
NSRange range = NSMakeRange(0, length); 
while(range.location != NSNotFound)
{
  range = [str rangeOfString: @"cake" options:0 range:range];
  if(range.location != NSNotFound)
  {
    range = NSMakeRange(range.location + range.length, length - (range.location + range.length));
    count++; 
  }
}

Related questions

Constants in Objective-C

I'm developing a Cocoa application, and I'm using constant NSStrings as ways to store key names for my preferences. I understand this is a good idea because it allows easy changing of keys if necessary. Plus, it's the whole 'separate …

Read More
Remove all whitespaces from NSString

I've been trying to get rid of the white spaces in an NSString, but none of the methods I've tried worked. I have "this is a test" and I want to get "thisisatest". I've used whitespaceCharacterSet, which is supposed to …

Read More
Understanding NSString comparison

Both the following comparisons evaluate to true: 1) @"foo" == @"foo"; 2) NSString *myString1 = @"foo"; NSString *myString2 = @"foo"; myString1 == myString2; However, there are definitely times where two NSStrings cannot be compared using the equality operator, and [myString1 isEqualToString:myString2] is required instead. Can …

Read More