I need to find a word or several words. With this method, however, I find also piece of word.
NSString *searchString = [NSString stringWithFormat:#"%#",searchField.text];
NSRange range = [textString rangeOfString : searchString];
if (range.location != NSNotFound) {
NSLog(#"textString = %#", textString);
}
I need the word / words exact
How can I do?
Thank you!
There are various ways of parsing/finding sub-strings in NSString:
NSString itself
NSRegularExpression. This would probably better suit your needs since you can tackle the scenario of surrounding white-spaces around words. Thus is won't return the cat from catapult when searching for cat.
NSScanner (most likely overkill for you needs)
... and they, of course, each have their PROs and CONs.
NSString has 9 methods grouped under "Finding Characters and Substrings". Methods such as:
-rangeOfString:
Finds and returns the range of the first occurrence of a given string within the receiver.
NSRegularExpression has 5 methods grouped under "Searching Strings Using Regular Expressions". Methods such as:
-numberOfMatchesInString: options: range:
Returns the number of matches of the regular expression within the specified range of the string.
It might also be useful to know about NSScanner, but this class would be more useful if you're parsing the string than simply looking for sub-parts.
What happens if you add a space at the end of the search string, like so:
NSString *searchString = [NSString stringWithFormat:#"%# ",searchField.text];
If the string from searchField.text already ends with a space, you would have to remove it.
This is not a perfect solution yet, for example you would not find the search string if it is at the end of a sentence. Instead what you could do is not adding the whitespace character, but instead look at the character after the hit and make sure that it is not a letter. For this, take a look at the class NSCharacterSet:
NSCharacterSet * letters = [NSCharacterSet letterCharacterSet];
if (![letters characterIsMember:[textString characterAtIndex:(range.location+searchString.length)]]) {
...
}
Related
I know I can check if a string contains uppercase letters but is there some built in function in Objective-C to check if all characters are uppercase letters? I want to avoid looping through each character to see if it contains a lowercase letter and then break out of the loop if it contains one as this takes up more memory and takes more time. Time is a constraint as I have to process thousands of strings.
An alternative approach that might appeal given your concerns: Use NSString's rangeOfCharactersFromSet: passing it NSCharacterSet's lowercaseLetterCharacterSet. If this finds anything then the string isn't all uppercase. It's a single line expression like the other current answers, but doesn't involve creating an uppercase copy of the string and works for all Unicode letters.
try this
NSString * myString;
[myString.uppercaseString isEqualToString:myString];
[your_string.uppercaseString isEqualToString:your_string];
If you need to process a lot of strings, especially long string may be following code will be faster
// In case you need process a lo of strings this set should be initialized before loop!
NSCharacterSet *set = [NSCharacterSet lowercaseLetterCharacterSet];
// check for allowed characters
BOOL isValid = ([string rangeOfCharacterFromSet:set].location == NSNotFound);
#implementation NSString (uppercaseOnly)
- (BOOL) allUpperCase {
return [self rangeOfCharacterFromSet:[[NSCharacterSet upperCaseLetterCharacterSet] invertedSet]].location == NSNotFound;
}
I created an array called NSArray citiesList from a text file separating each object by the "," at the end of the line. Here is what the raw data looks like from the text file.
City:San Jose|County:Santa Clara|Pop:945942,
City:San Francisco|County:San Francisco|Pop:805235,
City:Oakland|County:Alameda|Pop:390724,
City:Fremont|County:Alameda|Pop:214089,
City:Santa Rosa|County:Sonoma|Pop:167815,
The citiesList array is fine (I can see count the objects, see the data, etc.) Now I want to parse out the city and Pop: in each of the array objects. I assume that you create a for loop to run through the objects, so if I wanted to create a mutable array called cityNames to populate just the city names into this array I would use this kind of for loop:
SMutableArray *cityNames = [NSMutableArray array];
for (NSString *i in citiesList) {
[cityNames addObject:[???]];
}
My question is what is what query should I use to find just the City: San Francisco from the objects in my array?
You can continue to use componentsSeparatedByString to divide up the sections and key/value pairs. Or you can use an NSScanner to read through the string parsing out the key/value pairs. You could use rangeOfString to find the "|" and then extract a range. So many options.
Many good suggestions in the answers here in case you really want to construct an algorithm to parse the string.
As an alternative to that, you can also look at it as a problem of declaring the structure of the data and then just have the system do the parsing. For a case like yours, regular expressions will do that nicely. Whether you prefer to do it one way or the other is largely a question of taste and coding standards.
In your specific case (if the city name is all you need to extract from the string), then also notice that there is a bit of a shortcut available that will turn it into a one-line solution: Match the whole string, define a single capture group and substitute that one to make a new string:
NSString *city = [i stringByReplacingOccurrencesOfString: #".*City:(.*?)\\|.*"
withString: #"$1"
options: NSRegularExpressionSearch
range: NSMakeRange(0, row.length)];
The variable i is the same that you have defined in your for-loop, i.e. a string containing a string representing a line in your input file:
City:San Jose|County:Santa Clara|Pop:945942,
I have added the initial .* to make the pattern robust to future new fields added to the rows. You can remove it if you don't like it.
The $1 in the substitution string represents the first capture group, i.e. the parenthesis in the regex pattern. In this specific case, the substring containing the city name. Had there been more capture groups, they would have been named $2-$9. You can check the documentation on NSRegularExpression and NSString if you want to know more.
Regular expressions are a topic all of their own, not confined to the Cocoa, although all platforms use regex implementations with their own idiosyncrasies.
You want to use componentsSeparatedByString: as below. (These lines do no error checking)
NSArray *fields = [i componentsSeparatedByString:#"|"];
NSString *city = [[[fields objectAtIndex:0] componentsSeparatedByString:#":"] objectAtIndex:1];
NSString *county = [[[fields objectAtIndex:1] componentsSeparatedByString:#":"] objectAtIndex:1];
If you can drop the keys, and a couple delimiters like this:
San Jose|Santa Clara|945942
San Francisco|San Francisco|805235
Oakland|Alameda|390724
Fremont|Alameda|214089
Santa Rosa|Sonoma|167815
Then you can simplify the code (still no error checking):
NSArray *fields = [i componentsSeparatedByString:#"|"];
NSString *city = [fields objectAtIndex:0];
NSString *county = [fields objectAtIndex:1];
for (NSString *i in citiesList) {
// Divide each city into an array, where object 0 is the name, 1 is county, 2 is pop
NSArray *stringComponents = [i componentsSeparatedByString:#"|"];
// Remove "City:" from string and add the city name to the array
NSString *cityName = [[stringComponents objectAtIndex:0] stringByReplacingCharactersInRange:NSMakeRange(0, 5) withString:#""];
[cityNames addObject:cityName];
}
I have several NSStrings with a format similar to the one below:
"Hello, how are you?"
How can I break the string into an array of words? For example, for the above sentence I would expect an array consisting of "Hello,", "how", "are", "you?"
Usually I would break the string into words by using the function [NSString componentsSeparatedByCharactersInSet: NSCharacterSet set]
However this won't work in this situation because the spaces between the words are of unequal length. Note I will not be aware of the size of each word and the space between them.
How can I accomplish this? I am working on an app for OSX not iOS.
EDIT: My eventual goal is to retrieve the second word in the sentence. If there is a easier way to do this without breaking the string into an array please feel free to suggest it.
Try this:
NSMutableArray *parts = [NSMutableArray arrayWithArray:[str componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]];
[parts removeObjectIdenticalTo:#""];
NSString *res = [parts objectAtIndex:1]; // The second string
Well, you could actually write a loop to iterate through the characters and find the first non-blank after the first blank, then iterate further to find the ending blank (or end of line). Would probably be about 5x faster (with much fewer object allocations) than using one of the other methods, and could be done in about 10 lines.
If you dont want to use a CharacterSet try this to remove extra spaces:
NSString* string = #"word1, word2 word3 word4";
bool done = false;
do {
NSString tempStr = [string stringByReplacingOccurrencesOfString:#" " withString:#" "];
done = [string isEqualToString:tempStr];
string = tempStr;
} while (!done);
NSLog(#"%#", string);
this will output "word1, word2 word3 word4"
I am splitting an NSString like this: (filter string is an nsstring)
seperatorSet = [NSMutableCharacterSet whitespaceAndNewlineCharacterSet];
[seperatorSet formUnionWithCharacterSet:[NSCharacterSet punctuationCharacterSet]];
NSMutableArray *words = [[filterString componentsSeparatedByCharactersInSet:seperatorSet] mutableCopy];
I want to put words back into the form of filter string with the original punctuation and spacing. The reason I want to do this is I want to change some words and put it back together as it was originally.
A more robust way to split by words is to use string enumeration. A space is not always the delimiter and not all languages delimit spaces anyway (e.g. Japanese).
NSString * string = #" \n word1! word2,%$?'/word3.word4 ";
[string enumerateSubstringsInRange:NSMakeRange(0, string.length)
options:NSStringEnumerationByWords
usingBlock:
^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) {
NSLog(#"Substring: '%#'", substring);
}];
// Logs:
// Substring: 'word1'
// Substring: 'word2'
// Substring: 'word3'
// Substring: 'word4'
NSString *myString = #"Foo Bar Blah B..";
NSArray *myWords = [myString componentsSeparatedByCharactersInSet:
[NSCharacterSet characterSetWithCharactersInString:#" "]
];
NSString* string = [myWords componentsJoinedByString: #" "];
NSLog(#"%#",string);
Since you eliminate the original punctuation, there's no way to turn it back automatically.
The only way is not to use componentsSeparatedByCharactersInSet.
An alternative solution may be to iterate through the string and, for each char, check if it belongs to your character set.
If yes, add the char to a list and the substring to another list (you may use NSMutableArray class).
This way, for example, you know that the punctuation char between the first and the second substring is the first character in your list of separators.
You can use the pathArray componentsJoinedByString: method of the array class to rejoin the words:
NSString *orig = [words pathArray componentsJoinedByString:#" "];
How are you determining which words need to be replaced? Instead of breaking it apart in the first place, perhaps using -stringByReplacingOccurrencesOfString:withString:options:range: would be more suitable.
My guess is you may not be using the best API. If you're really worried about words, you should be using a word-based API. I'm a bit hazy on whether that would be NSDataDetector or something else. (I believe NSRegularExpression can deal with word boundaries in a smarter way.)
If you are using Mac OS X 10.7+ or iOS 4+ you can use NSRegularExpression, The pattern to replace a word is: "\b word \b" - (no spaces around word) \b matches a word boundary. Look at methods replaceMatchesInString:options:range:withTemplate: and stringByReplacingMatchesInString:options:range:withTemplate:.
Under 10.6 pr earlier if you wish to use regular expressions you can wrap the regcomp/regexec C-based functions, they support word boundaries as well. However you may prefer to use one of the other Cocoa options mentioned in other answers for this simple case.
I'd like to let a string change letters to lowercase or uppercase randomly(in Xcode).
for example: "example" to "ExaMpLe" or "eXAMPle" or ExAmPlE" or something else like this randomly..
hot can i solve this?
thanks
You could either use the -uppercaseString and -lowercaseString methods on substrings, or use the toupper() and tolower() functions on characters. There's no way to simply filter a string; you'll want to use either an NSMutableString or a C array of characters.
See this question for how to get a random boolean value, which you can use to decide whether a character should be uppercase or lowercase.
NSString has both a lowercaseString and uppercaseString method. You can iterate over the characters in a string as a sequence of substrings, using some random source to call the appropriate lower/upper case on each of them, collecting the result. Something like...
NSMutableString result = [NSMutableString string];
for (NSUInteger i = 0; i < [myString length]; i++)
{
NSString *substring = [myString substringWithRange:NSMakeRange(i, 1)];
[result appendString:(rand() % 2) ? [substring lowercaseString]
: [substring uppercaseString]];
}
You may prefer a better source of entropy than rand, but it'll do for an example (don't forget to seed it if you use this case as is). If the strings are large, you can do it in-place on an NSMutableString.
You could break the word into an array of letters, and loop over this using a random number to determining case, after looping the array, simply stick the letters back together using NSMutableString.
NSString had a uppercaseString and lowercaseString methods you can use.