Detect whole word in NSStrings - ios

Question

How do I detect if an NSString contains a specific word, e.g. is.
If the NSString is Here is my string. His isn't a mississippi isthmus. It is...? The method should detect the word is and return YES.
However, if the NSString is His isn't a mississipi isthmus, it should return NO.
I tried using if ([text rangeOfString:#"is" options:NSCaseInsensitiveSearch].location != NSNotFound) { ... } but it detects characters not words.

Answer 1

Use "regular expression" search with the "word boundary pattern" \b:
NSString *text = #"Here is my string. His isn't a mississippi isthmus. It is...";
NSString *pattern = #"\\bis\\b";
NSRange range = [text rangeOfString:pattern options:NSRegularExpressionSearch|NSCaseInsensitiveSearch];
if (range.location != NSNotFound) { ... }
This works also for cases like "Is it?" or "It is!", where the word is not surrounded by spaces.
In Swift 2 this would be
let text = "Here is my string. His isn't a mississippi isthmus. It is..."
let pattern = "\\bis\\b"
if let range = text.rangeOfString(pattern, options: [.RegularExpressionSearch, .CaseInsensitiveSearch]) {
print ("found:", text.substringWithRange(range))
}
Swift 3:
let text = "Here is my string. His isn't a mississippi isthmus. It is..."
let pattern = "\\bis\\b"
if let range = text.range(of: pattern, options: [.regularExpression, .caseInsensitive]) {
print ("found:", text.substring(with: range))
}
Swift 4:
let text = "Here is my string. His isn't a mississippi isthmus. It is..."
let pattern = "\\bis\\b"
if let range = text.range(of: pattern, options: [.regularExpression, .caseInsensitive]) {
print ("found:", text[range])
}
Swift 5 (using the new raw string literals):
let text = "Here is my string. His isn't a mississippi isthmus. It is..."
let pattern = #"\bis\b"#
if let range = text.range(of: pattern, options: [.regularExpression, .caseInsensitive]) {
print ("found:", text[range])
}

Answer 2

Use NSRegularExpressionSearch option with \b to match word boundary characters.
Like this:
NSString *string = #"Here is my string. His isn't a mississippi isthmus. It is...";
if(NSNotFound != [string rangeOfString:#"\\bis\\b" options:NSRegularExpressionSearch].location) {//...}

Answer 3

What about
if ([text rangeOfString:#" is " options:NSCaseInsensitiveSearch].location != NSNotFound) { ... }

Answer 4

You could use regular expressions, as suggested, or you could analyze the words linguistically:
NSString *string = #"Here is my string. His isn't a mississippi isthmus. It is...";
__block BOOL containsIs = NO;
[string enumerateLinguisticTagsInRange:NSMakeRange(0, [string length]) scheme:NSLinguisticTagSchemeTokenType options:NSLinguisticTaggerOmitPunctuation | NSLinguisticTaggerOmitWhitespace | NSLinguisticTaggerOmitOther orthography:nil usingBlock:^(NSString *tag, NSRange tokenRange, NSRange sentenceRange, BOOL *stop){
NSString *substring = [string substringWithRange:tokenRange];
if (containsIs)
if ([substring isEqualToString:#"n't"])
containsIs = NO; // special case because "isn't" are actually two separate words
else
*stop = YES;
else
containsIs = [substring isEqualToString:#"is"];
}];
NSLog(#"'%#' contains 'is': %#", string, containsIs ? #"YES" : #"NO");