Remove all whitespaces from NSString

问题:

I've been trying to get rid of the white spaces in an NSString, but none of the methods I've tried worked.

I have "this is a test" and I want to get "thisisatest".

I've used whitespaceCharacterSet, which is supposed to eliminate the white spaces.

NSString *search = [searchbar.text stringByTrimmingCharactersInSet:
                           [NSCharacterSet whitespaceCharacterSet]];

but I kept getting the same string with spaces. Any ideas?

回答1:

stringByTrimmingCharactersInSet only removes characters from the beginning and the end of the string, not the ones in the middle.

1) If you need to remove only a given character (say the space character) from your string, use:

[yourString stringByReplacingOccurrencesOfString:@" " withString:@""]

2) If you really need to remove a set of characters (namely not only the space character, but any whitespace character like space, tab, unbreakable space, etc), you could split your string using the whitespaceCharacterSet then joining the words again in one string:

NSArray* words = [yourString componentsSeparatedByCharactersInSet :[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSString* nospacestring = [words componentsJoinedByString:@""];

Note that this last solution has the advantage of handling every whitespace character and not only spaces, but is a bit less efficient that the stringByReplacingOccurrencesOfString:withString:. So if you really only need to remove the space character and are sure you won't have any other whitespace character than the plain space char, use the first method.

回答2:

I prefer using regex like this:

NSString *myString = @"this is a test";
NSString *myNewString = [myString stringByReplacingOccurrencesOfString:@"\\s"
                                     withString:@""
                                        options:NSRegularExpressionSearch
                                          range:NSMakeRange(0, [myStringlength])];
 //myNewString will be @"thisisatest"

---

You can make yourself a category on NSString to make life even easier:

- (NSString *) removeAllWhitespace
{
    return [self stringByReplacingOccurrencesOfString:@"\\s" withString:@""
                                              options:NSRegularExpressionSearch
                                                range:NSMakeRange(0, [self length])];

}

Here is a unit test method on it too:

- (void) testRemoveAllWhitespace
{
    NSString *testResult = nil;

    NSArray *testStringsArray        = @[@""
                                         ,@"    "
                                         ,@"  basicTest    "
                                         ,@"  another Test \n"
                                         ,@"a b c d e f g"
                                         ,@"\n\tA\t\t \t \nB    \f  C \t  ,d,\ve   F\r\r\r"
                                         ,@"  landscape, portrait,     ,,,up_side-down   ;asdf;  lkjfasdf0qi4jr0213 ua;;;;af!@@##$$ %^^ & *  * ()+  +   "
                                         ];

    NSArray *expectedResultsArray   = @[@""
                                        ,@""
                                        ,@"basicTest"
                                        ,@"anotherTest"
                                        ,@"abcdefg"
                                        ,@"ABC,d,eF"
                                        ,@"landscape,portrait,,,,up_side-down;asdf;lkjfasdf0qi4jr0213ua;;;;af!@@##$$%^^&**()++"
                                        ];

    for (int i=0; i < [testStringsArray count]; i++)
    {
        testResult = [testStringsArray[i] removeAllWhitespace];
        STAssertTrue([testResult isEqualToString:expectedResultsArray[i]], @"Expected: \"%@\" to become: \"%@\", but result was \"%@\"",
                     testStringsArray[i], expectedResultsArray[i], testResult);
    }
}

回答3:

Easy task using stringByReplacingOccurrencesOfString

NSString *search = [searchbar.text stringByReplacingOccurrencesOfString:@" " withString:@""];

回答4:

This may help you if you are experiencing \u00a0 in stead of (whitespace). I had this problem when I was trying to extract Device Contact Phone Numbers. I needed to modify the phoneNumber string so it has no whitespace in it.

NSString* yourString = [yourString stringByReplacingOccurrencesOfString:@"\u00a0" withString:@""];

When yourString was the current phone number.

回答5:

stringByReplacingOccurrencesOfString will replace all white space with in the string non only the starting and end

Use

[YourString stringByTrimmingCharactersInSet:[NSCharacterSet  whitespaceAndNewlineCharacterSet]]

回答6:

- (NSString *)removeWhitespaces {
  return [[self componentsSeparatedByCharactersInSet:
                    [NSCharacterSet whitespaceCharacterSet]]
      componentsJoinedByString:@""];
}

回答7:

This for me is the best way SWIFT

        let myString = "  ciao   \n              ciao     "
        var finalString = myString as NSString

        for character in myString{
        if character == " "{

            finalString = finalString.stringByReplacingOccurrencesOfString(" ", withString: "")

        }else{
            finalString = finalString.stringByReplacingOccurrencesOfString("\n", withString: "")

        }

    }
     println(finalString)

and the result is : ciaociao

But the trick is this!

 extension String {

    var NoWhiteSpace : String {

    var miaStringa = self as NSString

    if miaStringa.containsString(" "){

      miaStringa =  miaStringa.stringByReplacingOccurrencesOfString(" ", withString: "")
    }
        return miaStringa as String

    }
}

let myString = "Ciao   Ciao       Ciao".NoWhiteSpace  //CiaoCiaoCiao

回答8:

Use below marco and remove the space.

#define TRIMWHITESPACE(string) [string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]

in other file call TRIM :

    NSString *strEmail;
    strEmail = TRIM(@"     this is the test.");

May it will help you...

回答9:

That is for removing any space that is when you getting text from any text field but if you want to remove space between string you can use

xyz =[xyz.text stringByReplacingOccurrencesOfString:@" " withString:@""];

It will replace empty space with no space and empty field is taken care of by below method:

searchbar.text=[searchbar.text stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceCharacterSet]];

回答10:

pStrTemp = [pStrTemp stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

回答11:

I strongly suggest placing this somewhere in your project:

extension String {
    func trim() -> String {
        return self.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
    }

    func trim(withSet: NSCharacterSet) -> String {
        return self.stringByTrimmingCharactersInSet(withSet)
    }
}