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

Question

There is a substring that occurs in a string several times. I use rangeOfString, but it seems that it can only find the first location. How can I find all the locations of the substring?
NSString *subString1 = #"</content>";
NSString *subString2 = #"--\n";
NSRange range1 = [newresults rangeOfString:subString1];
NSRange range2 = [newresults rangeOfString:subString2];
int location1 = range1.location;
int location2 = range2.location;
NSLog(#"%i",location1);
NSLog(#"%i",location2);

Answer 1

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;
}
}

Answer 2

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
}
}
//Apply
textLabel.attributedText = mutableAttributedString;
And this output-

Answer 3

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;
}

Answer 4

Passing nil to [string rangeOfString:substring options:nil range:searchRange]; shows a warning.
To get rid of the warning, put in an enum from this group
enum {
NSCaseInsensitiveSearch = 1,
NSLiteralSearch = 2,
NSBackwardsSearch = 4,
NSAnchoredSearch = 8,
NSNumericSearch = 64,
NSDiacriticInsensitiveSearch = 128,
NSWidthInsensitiveSearch = 256,
NSForcedOrderingSearch = 512,
NSRegularExpressionSearch = 1024
};
https://developer.apple.com/library/ios/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/index.html#//apple_ref/doc/constant_group/Search_and_Comparison_Options

Answer 5

Here is a version in Swift 2.2 of PengOne's answer with input from kevinlawler and Gibtang
Note: string and substring are of type NSString
let fullStringLength = (string as String).characters.count
var searchRange = NSMakeRange(0, fullStringLength)
while searchRange.location < fullStringLength {
searchRange.length = fullStringLength - searchRange.location
let foundRange = string.rangeOfString(substring as String, options: .CaseInsensitiveSearch, range: searchRange)
if foundRange.location != NSNotFound {
// found an occurrence of the substring! do stuff here
searchRange.location = foundRange.location + 1
} else {
// no more strings to find
break
}
}

Answer 6

I suggest using regular expression because it's a more declarative way and has fewer lines of code to write.
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:#"%#" options:nil error:nil];
NSString *toSearchStr = #"12312 %# Text %# asdsa %#";
__block int occurs = 0;
[regex enumerateMatchesInString:toSearchStr options:0 range:NSMakeRange(0, toSearchStr.length) usingBlock:^(NSTextCheckingResult * _Nullable result, NSMatchingFlags flags, BOOL * _Nonnull stop) {
occurs++;
}];
// occurs == 3