How do I check if a string contains another string

Question

How can I check if a string (NSString) contains another smaller string?

I was hoping for something like:

NSString *string = @"hello bla bla";
NSLog(@"%d",[string containsSubstring:@"hello"]);

But the closest I could find was:

if ([string rangeOfString:@"hello"] == 0) {
    NSLog(@"sub string doesnt exist");
} 
else {
    NSLog(@"exists");
}

Anyway, is that the best way to find if a string contains another string?

Answer 1

Use the option NSCaseInsensitiveSearch with rangeOfString:options:

NSString *me = @"toBe" ;
NSString *target = @"abcdetobe" ;
NSRange range = [target  rangeOfString: me options: NSCaseInsensitiveSearch];
NSLog(@"found: %@", (range.location != NSNotFound) ? @"Yes" : @"No");
if (range.location != NSNotFound) {
// your code
}

Output result is found:Yes

The options can be "or'ed" together and include:

NSCaseInsensitiveSearch NSLiteralSearch NSBackwardsSearch and more

Answer 2

NOTE: This answer is now obsolete

Create a category for NSString:

@interface NSString ( SubstringSearch )
    - (BOOL)containsString:(NSString *)substring;
@end

// - - - - 

@implementation NSString ( SubstringSearch )

- (BOOL)containsString:(NSString *)substring
{    
    NSRange range = [self rangeOfString : substring];
    BOOL found = ( range.location != NSNotFound );
    return found;
}

@end

EDIT: Observe Daniel Galasko's comment below regarding naming

Answer 3

If you need this once write:

NSString *stringToSearchThrough = @"-rangeOfString method finds and returns the range of the first occurrence of a given string within the receiver.";
BOOL contains = [stringToSearchThrough rangeOfString:@"occurence of a given string"].location != NSNotFound;

Answer 4

SWift 4 And Above

 let str = "Hello iam midhun"

   if str.contains("iam") {
     //contain substring
   }
   else {
     //doesn't contain substring
   }

Answer 5

Oneliner (Smaller amount of code. DRY, as you have only one NSLog):

NSString *string = @"hello bla bla";
NSLog(@"String %@", ([string rangeOfString:@"bla"].location == NSNotFound) ? @"not found" : @"cotains bla"); 

Answer 6

So personally I really hate NSNotFound but understand its necessity.

But some people may not understand the complexities of comparing against NSNotFound

For example, this code:

- (BOOL)doesString:(NSString*)string containString:(NSString*)otherString {
    if([string rangeOfString:otherString].location != NSNotFound)
        return YES;
    else
        return NO;
}

has its problems:

1) Obviously if otherString = nil this code will crash. a simple test would be:

NSLog(@"does string contain string - %@", [self doesString:@"hey" containString:nil] ? @"YES": @"NO");

results in !! CRASH !!

2) What is not so obvious to someone new to objective-c is that the same code will NOT crash when string = nil. For example, this code:

NSLog(@"does string contain string - %@", [self doesString:nil containString:@"hey"] ? @"YES": @"NO");

and this code:

NSLog(@"does string contain string - %@", [self doesString:nil containString:nil] ? @"YES": @"NO");

will both result in

does string contains string - YES

Which is clearly NOT what you want.

So the better solution that I believe works is to use the fact that rangeOfString returns the length of 0 so then a better more reliable code is this:

- (BOOL)doesString:(NSString*)string containString:(NSString*)otherString {
    if(otherString && [string rangeOfString:otherString].length)
        return YES;
    else
        return NO;
}

OR SIMPLY:

- (BOOL)doesString:(NSString*)string containString:(NSString*)otherString {
    return (otherString && [string rangeOfString:otherString].length);
}

which will for cases 1 and 2 will return

does string contains string - NO

That's my 2 cents ;-)

Please check out my Gist for more helpful code.