Find all locations of substring in NSString (not just first)

You can use rangeOfString:options:range: and set the third argument to be beyond the range of the first occurrence. For example, you can do something like this:

NSRange searchRange = NSMakeRange(0,string.length);NSRange foundRange;while (searchRange.location < string.length) {    searchRange.length = string.length-searchRange.location;    foundRange = [string rangeOfString:substring options:0 range:searchRange];    if (foundRange.location != NSNotFound) {        // found an occurrence of the substring! do stuff here        searchRange.location = foundRange.location+foundRange.length;    } else {        // no more substring to find        break;    }}

Swift 3.0

Find all locations of substring i

let text = "This is the text and i want to replace something"let mutableAttributedString = NSMutableAttributedString(string: text)var searchRange = NSRange(location: 0, length: text.characters.count)var foundRange = NSRange()while searchRange.location < text.characters.count {    searchRange.length = text.characters.count - searchRange.location    foundRange = (text as NSString).range(of: "i", options: NSString.CompareOptions.caseInsensitive, range: searchRange)    if foundRange.location != NSNotFound {        // found an occurrence of the substring! do stuff here        searchRange.location = foundRange.location + foundRange.length        mutableAttributedString.addAttribute(NSForegroundColorAttributeName, value: UIColor.red, range: foundRange)    }    else {        // no more substring to find        break    }}//ApplytextLabel.attributedText = mutableAttributedString;

And this output-

This is my solution. Basically, the algorithm traverses the string looking for substring matches and returns those matches in an array.

Since an NSRange is a struct it cannot be added to the array directly. By using NSValue, I can encode the match first and then add it to the array. To retrieve the range, I then decode the NSValue object to an NSRange.

#import <Foundation/Foundation.h>NSRange makeRangeFromIndex(NSUInteger index, NSUInteger length) {    return NSMakeRange(index, length - index);}NSArray<NSValue *> * allLocationsOfStringMatchingSubstring(NSString *text, NSString *pattern) {    NSMutableArray *matchingRanges = [NSMutableArray new];    NSUInteger textLength = text.length;    NSRange match = makeRangeFromIndex(0, textLength);    while(match.location != NSNotFound) {        match = [text rangeOfString:pattern options:0L range:match];        if (match.location != NSNotFound) {            NSValue *value = [NSValue value:&match withObjCType:@encode(NSRange)];            [matchingRanges addObject:value];            match = makeRangeFromIndex(match.location + 1, textLength);        }    }    return [matchingRanges copy];}int main(int argc, const char * argv[]) {    @autoreleasepool {        NSString *text = @"TATACCATGGGCCATCATCATCATCATCATCATCATCATCATCACAG";        NSString *pattern = @"CAT";        NSArray<NSValue *> *matches = allLocationsOfStringMatchingSubstring(text, pattern);        NSLog(@"Text: %@", text);        NSLog(@"Pattern: %@", pattern);        NSLog(@"Number of matches found: %li", matches.count);        [matches enumerateObjectsUsingBlock:^(NSValue *obj, NSUInteger idx, BOOL *stop) {            NSRange match;            [obj getValue:&match];            NSLog(@"   Match found at index: %li", match.location);        }];    }    return 0;}