Replace multiple characters in a string in Objective-C? - iphone

In PHP I can do this:
$new = str_replace(array('/', ':', '.'), '', $new);
...to replace all instances of the characters / : . with a blank string (to remove them)
Can I do this easily in Objective-C? Or do I have to roll my own?
Currently I am doing multiple calls to stringByReplacingOccurrencesOfString:
strNew = [strNew stringByReplacingOccurrencesOfString:#"/" withString:#""];
strNew = [strNew stringByReplacingOccurrencesOfString:#":" withString:#""];
strNew = [strNew stringByReplacingOccurrencesOfString:#"." withString:#""];
Thanks,
matt

A somewhat inefficient way of doing this:
NSString *s = #"foo/bar:baz.foo";
NSCharacterSet *doNotWant = [NSCharacterSet characterSetWithCharactersInString:#"/:."];
s = [[s componentsSeparatedByCharactersInSet: doNotWant] componentsJoinedByString: #""];
NSLog(#"%#", s); // => foobarbazfoo
Look at NSScanner and -[NSString rangeOfCharacterFromSet: ...] if you want to do this a bit more efficiently.

There are situations where your method is good enough I think matt.. BTW, I think it's better to use
[strNew setString: [strNew stringByReplacingOccurrencesOfString:#":" withString:#""]];
rather than
strNew = [strNew stringByReplacingOccurrencesOfString:#"/" withString:#""];
as I think you're overwriting an NSMutableString pointer with an NSString which might cause a memory leak.

Had to do this recently and wanted to share an efficient method:
(assuming someText is a NSString or text attribute)
NSString* someText = #"1232342jfahadfskdasfkjvas12!";
(this example will strip numbers from a string)
[someText stringByReplacingOccurrencesOfString:#"[^0-9]" withString:#"" options:NSRegularExpressionSearch range:NSMakeRange(0, [someText length])];
Keep in mind that you will need to escape regex literal characters using Obj-c escape character:
(obj-c uses a double backslash to escape special regex literals)
...stringByReplacingOccurrencesOfString:#"[\\\!\\.:\\/]"
What makes this interesting is that NSRegularExpressionSearch option is little used but can lead to some very powerful controls:
You can find a nice iOS regex tutorial here and more on regular expressions at regex101.com

Essentially the same thing as Nicholas posted above, but if you want to remove everything EXCEPT a set of characters (say you want to remove everything that isn't in the set "ABCabc123") then you can do the following:
NSString *s = #"A567B$%C^.123456abcdefg";
NSCharacterSet *doNotWant = [[NSCharacterSet characterSetWithCharactersInString:#"ABCabc123"] invertedSet];
s = [[s componentsSeparatedByCharactersInSet: doNotWant] componentsJoinedByString: #""];
NSLog(#"%#", s); // => ABC123abc
Useful in stripping out symbols and such, if you only want alphanumeric.

+ (NSString*) decodeHtmlUnicodeCharactersToString:(NSString*)str
{
NSMutableString* string = [[NSMutableString alloc] initWithString:str]; // #&39; replace with '
NSString* unicodeStr = nil;
NSString* replaceStr = nil;
int counter = -1;
for(int i = 0; i < [string length]; ++i)
{
unichar char1 = [string characterAtIndex:i];
for (int k = i + 1; k < [string length] - 1; ++k)
{
unichar char2 = [string characterAtIndex:k];
if (char1 == '&' && char2 == '#' )
{
++counter;
unicodeStr = [string substringWithRange:NSMakeRange(i + 2 , 2)]; // read integer value i.e, 39
replaceStr = [string substringWithRange:NSMakeRange (i, 5)]; // #&39;
[string replaceCharactersInRange: [string rangeOfString:replaceStr] withString:[NSString stringWithFormat:#"%c",[unicodeStr intValue]]];
break;
}
}
}
[string autorelease];
if (counter > 1)
return [self decodeHtmlUnicodeCharactersToString:string];
else
return string;
}

Here is an example in Swift 3 using the regularExpression option of replacingOccurances.
Use replacingOccurrences along with a the String.CompareOptions.regularExpression option.
Example (Swift 3):
var x = "<Hello, [play^ground+]>"
let y = x.replacingOccurrences(of: "[\\[\\]^+<>]", with: "7", options: .regularExpression, range: nil)
print(y)
Output:
7Hello, 7play7ground777

If the characters you wish to remove were to be adjacent to each other you could use the
stringByReplacingCharactersInRange:(NSRange) withString:(NSString *)
Other than that, I think just using the same function several times isn't that bad. It is much more readable than creating a big method to do the same in a more generic way.

Create an extension on String...
extension String {
func replacingOccurrences(of strings:[String], with replacement:String) -> String {
var newString = self
for string in strings {
newString = newString.replacingOccurrences(of: string, with: replacement)
}
return newString
}
}
Call it like this:
aString = aString.replacingOccurrences(of:['/', ':', '.'], with:"")

Related

Replacing instances of a character with two different characters in Objective-C

I have a huge amount of NSStrings in a database that get passed to a view controller in an iOS app. They are formatted as "This is a message with $specially formatted$ content".
However, I need to change the '$' at the start of the special formatting with a '[' and the '$' at the end with ']'. I have a feeling I can use an NSScanner but so far all of my attempts have produced wackily concatenated strings!
Is there a simple way to recognise a substring encapsulated by '$' and swap them out with start/end characters? Please note that a lot of the NSStrings have multiple '$' substrings.
Thanks!
You can use regular expressions:
NSMutableString *str = [#"Hello $World$, foo $bar$." mutableCopy];
NSRegularExpression *regex;
regex = [NSRegularExpression regularExpressionWithPattern:#"\\$([^$]*)\\$"
options:0
error:NULL];
[regex replaceMatchesInString:str
options:0
range:NSMakeRange(0, [str length])
withTemplate:#"[$1]"];
NSLog(#"%#", str);
// Output:
// Hello [World], foo [bar].
The pattern #"\\$([^$]*)\\$" searches for
$<zero_or_more_characters_which_are_not_a_dollarsign>$
and all occurrences are then replaced by [...]. The pattern contains so many backslashes because the $ must be escaped in the regular expression pattern.
There is also stringByReplacingMatchesInString if you want to create a new string instead of modifying the original string.
I think replaceOccurrencesOfString: won't work cause you have start$ and end$.
But if you seperate the Strings with [string componentsSeperatedByString:#"$"] you get an Array of substrings, so every second string is your "$specially formatted$"-string
This should work!
NSString *str = #"This is a message with $specially formatted$ content";
NSString *original = #"$";
NSString *replacement1 = #"[";
NSString *replacement2 = #"]";
BOOL start = YES;
NSRange rOriginal = [str rangeOfString: original];
while (NSNotFound != rOriginal.location) {
str = [str stringByReplacingCharactersInRange: rOriginal withString:(start?replacement1:replacement2)];
start = !start;
rOriginal = [str rangeOfString: original];
}
NSLog(#"%#", str);
Enjoy Programming!
// string = #"This is a $special markup$ sentence."
NSArray *components = [string componentsSeparatedByString:#"$"];
// sanity checks
if (components.count < 2) return; // maybe no $ characters found
if (components.count % 2) return; // not an even number of $s
NSMutableString *out = [NSMutableString string];
for (int i=0; i< components.count; i++) {
[out appendString:components[i]];
[out appendString: (i % 2) ? #"]" : #"[" ];
}
// out = #"This is a [special markup] sentence."
Try this one
NSMutableString *string=[[NSMutableString alloc]initWithString:#"This is a message with $specially formatted$ content. This is a message with $specially formatted$ content"];
NSMutableString *string=[[NSMutableString alloc]initWithString:#"This is a message with $specially formatted$ content. This is a message with $specially formatted$ content"];
BOOL open=YES;
for (NSUInteger i=0; i<[string length];i++) {
if ([string characterAtIndex:i]=='$') {
if (open) {
[string replaceCharactersInRange:NSMakeRange(i, 1) withString:#"["];
open=!open;
}
else{
[string replaceCharactersInRange:NSMakeRange(i, 1) withString:#"]"];
open=!open;
}
}
}
NSLog(#"-->%#",string);
Output:
-->This is a message with [specially formatted] content. This is a message with [specially formatted] content

Objective-C: Find consonants in string

I have a string that contains words with consonants and vowels. How can I extract only consonants from the string?
NSString *str = #"consonants.";
Result must be:
cnsnnts
You could make a character set with all the vowels (#"aeiouy")
+ (id)characterSetWithCharactersInString:(NSString *)aString
then use the
- (NSString *)stringByTrimmingCharactersInSet:(NSCharacterSet *)set
method.
EDIT: This will only remove vowels at the beginning and end of the string as pointed out in the other post, what you could do instead is use
- (NSArray *)componentsSeparatedByCharactersInSet:(NSCharacterSet *)separator
then stick the components back together. You may also need to include capitalized versions of the vowels in the set, and if you want to also deal with accents (à á è è ê ì etc...) you'll probably have to include that also.
Unfortunately stringByTrimmingCharactersInSet wont work as it only trim leading and ending characters, but you could try using a regular expression and substitution like this:
[[NSRegularExpression
regularExpressionWithPattern:#"[^bcdefghjklmnpqrstvwx]"
options:NSRegularExpressionCaseInsensitive
error:NULL]
stringByReplacingMatchesInString:str
options:0
range:NSMakeRange(0, [str length])
withTemplate:#""]
You probably want to tune the regex and options for your needs.
Possible, for sure not-optimal, solution. I'm printing intermediate results for your learning. Take care of memory allocation (I didn't care). Hopefully someone will send you a better solution, but you can copy and paste this for the moment.
NSString *test = #"Try to get all consonants";
NSMutableString *found = [[NSMutableString alloc] init];
NSInteger loc = 0;
NSCharacterSet *consonants = [NSCharacterSet characterSetWithCharactersInString:#"bcdfghjklmnpqrstvwxyz"];
while(loc!=NSNotFound && loc<[test length]) {
NSRange r = [[test lowercaseString] rangeOfCharacterFromSet:consonants options:0 range:NSMakeRange(loc, [test length]-loc)];
if(r.location!=NSNotFound) {
NSString *temp = [test substringWithRange:r];
NSLog(#"Range: %# Temp: %#",NSStringFromRange(r), temp);
[found appendString:temp];
loc=r.location+r.length;
} else {
loc=NSNotFound;
}
}
NSLog(#"Found: %#",found);
Here is a NSString category that does the job:
- (NSString *)consonants
{
NSString *result = [NSString stringWithString:self];
NSCharacterSet *characterSet = [NSCharacterSet characterSetWithCharactersInString:#"aeiou"];
while(1)
{
NSRange range = [result rangeOfCharacterFromSet:characterSet options:NSCaseInsensitiveSearch];
if(range.location == NSNotFound)
break;
result = [result stringByReplacingCharactersInRange:range withString:#""];
}
return result;
}

how to remove () charracter

when i convert my array by following method , it adds () charracter.
i want to remove the () how can i do it..
NSMutableArray *rowsToBeDeleted = [[NSMutableArray alloc] init];
NSString *postString =
[NSString stringWithFormat:#"%#",
rowsToBeDeleted];
int index = 0;
for (NSNumber *rowSelected in selectedArray)
{
if ([rowSelected boolValue])
{
profileName = [appDelegate.archivedItemsList objectAtIndex:index];
NSString *res = [NSString stringWithFormat:#"%d",profileName.userID];
[rowsToBeDeleted addObject:res];
}
index++;
}
UPDATE - 1
when i print my array it shows like this
(
70,
71,
72
)
Here's a brief example of deleting the given characters from a string.
NSString *someString = #"(whatever)";
NSCharacterSet *charSet = [NSCharacterSet characterSetWithCharactersInString:#"()"];
NSMutableString *mutableCopy = [NSMutableString stringWithString:someString];
NSRange range;
for (range = [mutableCopy rangeOfCharacterFromSet:charSet];
range.location != NSNotFound;
[mutableCopy deleteCharactersInRange:range],
range = [mutableCopy rangeOfCharacterFromSet:charSet]);
All this does is get a mutable copy of the string, set up a character set with any and all characters to be stripped from the string, and find and remove each instance of those characters from the mutable copy. This might not be the cleanest way to do it (I don't know what the cleanest is) - obviously, you have the option of doing it Ziminji's way as well. Also, I abused a for loop for the hell of it. Anyway, that deletes some characters from a string and is pretty simple.
Try using NSArray’s componentsJoinedByString method to convert your array to a string:
[rowsToBeDeleted componentsJoinedByString:#", "];
The reason you are getting the parenthesis is because you are calling the toString method on the NSArray class. Therefore, it sounds like you just want to substring the resulting string. To do this, you can use a function like the following:
+ (NSString *) extractString: (NSString *)string prefix: (NSString *)prefix suffix: (NSString *)suffix {
int strLength = [string length];
int begIndex = [prefix length];
int endIndex = strLength - (begIndex + [suffix length]);
if (endIndex > 0) {
string = [string substringWithRange: NSMakeRange(begIndex, endIndex)];
}
return string;
}

Objective-C: Find numbers in string

I have a string that contains words as well as a number. How can I extract that number from the string?
NSString *str = #"This is my string. #1234";
I would like to be able to strip out 1234 as an int. The string will have different numbers and words each time I search it.
Ideas?
Here's an NSScanner based solution:
// Input
NSString *originalString = #"This is my string. #1234";
// Intermediate
NSString *numberString;
NSScanner *scanner = [NSScanner scannerWithString:originalString];
NSCharacterSet *numbers = [NSCharacterSet characterSetWithCharactersInString:#"0123456789"];
// Throw away characters before the first number.
[scanner scanUpToCharactersFromSet:numbers intoString:NULL];
// Collect numbers.
[scanner scanCharactersFromSet:numbers intoString:&numberString];
// Result.
int number = [numberString integerValue];
(Some of the many) assumptions made here:
Number digits are 0-9, no sign, no decimal point, no thousand separators, etc. You could add sign characters to the NSCharacterSet if needed.
There are no digits elsewhere in the string, or if there are they are after the number you want to extract.
The number won't overflow int.
Alternatively you could scan direct to the int:
[scanner scanUpToCharactersFromSet:numbers intoString:NULL];
int number;
[scanner scanInt:&number];
If the # marks the start of the number in the string, you could find it by means of:
[scanner scanUpToString:#"#" intoString:NULL];
[scanner setScanLocation:[scanner scanLocation] + 1];
// Now scan for int as before.
Self contained solution:
+ (NSString *)extractNumberFromText:(NSString *)text
{
NSCharacterSet *nonDigitCharacterSet = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
return [[text componentsSeparatedByCharactersInSet:nonDigitCharacterSet] componentsJoinedByString:#""];
}
Handles the following cases:
#"1234" → #"1234"
#"001234" → #"001234"
#"leading text get removed 001234" → #"001234"
#"001234 trailing text gets removed" → #"001234"
#"a0b0c1d2e3f4" → #"001234"
Hope this helps!
You could use the NSRegularExpression class, available since iOS SDK 4.
Bellow a simple code to extract integer numbers ("\d+" regex pattern) :
- (NSArray*) getIntNumbersFromString: (NSString*) string {
NSMutableArray* numberArray = [NSMutableArray new];
NSString* regexPattern = #"\\d+";
NSRegularExpression* regex = [[NSRegularExpression alloc] initWithPattern:regexPattern options:0 error:nil];
NSArray* matches = [regex matchesInString:string options:0 range:NSMakeRange(0, string.length)];
for( NSTextCheckingResult* match in matches) {
NSString* strNumber = [string substringWithRange:match.range];
[numberArray addObject:[NSNumber numberWithInt:strNumber.intValue]];
}
return numberArray;
}
Try this answer from Stack Overflow for a nice piece of C code that will do the trick:
for (int i=0; i<[str length]; i++) {
if (isdigit([str characterAtIndex:i])) {
[strippedString appendFormat:#"%c",[str characterAtIndex:i]];
}
}
By far the best solution! I think regexp would be better, but i kind of sux at it ;-) this filters ALL numbers and concats them together, making a new string. If you want to split multiple numbers change it a bit. And remember that when you use this inside a big loop it costs performance!
NSString *str= #"bla bla bla #123 bla bla 789";
NSMutableString *newStr = [[NSMutableString alloc] init];;
int j = [str length];
for (int i=0; i<j; i++) {
if ([str characterAtIndex:i] >=48 && [str characterAtIndex:i] <=59) {
[newStr appendFormat:#"%c",[str characterAtIndex:i]];
}
}
NSLog(#"%# as int:%i", newStr, [newStr intValue]);
Swift extension for getting number from string
extension NSString {
func getNumFromString() -> String? {
var numberString: NSString?
let thisScanner = NSScanner(string: self as String)
let numbers = NSCharacterSet(charactersInString: "0123456789")
thisScanner.scanUpToCharactersFromSet(numbers, intoString: nil)
thisScanner.scanCharactersFromSet(numbers, intoString: &numberString)
return numberString as? String;
}
}
NSPredicate is the Cocoa class for parsing string using ICU regular expression.

NSXMLParser Encoded by Windows-1252

So NSXMLParser has problems parsing strings using the Windows-1252 encoder. Now I did find a solution on this page to convert it to NSUTF8StringEncoding. But now it bumps into characters it can't parse.
So I figured out that it will work if I would escape special characters and then transfer it back after parsing it. For example:
string = [string stringByReplacingOccurrencesOfString:#":" withString:#"__58__"];
Since it is allowed to use the _ character without getting a parser error and in NSXMLParser I can transfer the value back to it's proper character.
So is there a way I can loop through all ASCII character so I can replace all special characters (Except <, > and _ of course)?
Totally untested. I don't even know if it compiles, but it may get you on the right track. string needs to be an NSMutableString.
NSRange r = NSMakeRange(0, [string length]);
while (r.location < [string length])
{
r = [string rangeOfCharactersFromSet:[NSCharacterSet symbolCharacterSet] options:0 range:r];
if (r.location != NSNotFound)
{
NSMutableString *replacement = [[NSMutableString alloc] initWithCapacity:6];
for (NSUInteger i = r.location; i <= NSMaxRange(r); i++)
{
unichar c = [string characterAtIndex:i];
if (c != "_")
{
[replacement appendFormat:#"__%d__", (unsigned)c];
}
}
[string replaceCharactersInRange:r withString:replacement];
[replacement release]; replacement = nil;
r.location = r.location + [string length] + 1;
r.length = [string length] - r.location;
}
}
Assuming you have a NSMutableString str, you can do the following:
NSMutableString *str = ...;
[str replaceOccurrencesOfString:":" withString:#"__58__"
options:NSLiteralSearch
range:NSMakeRange(0, [str length])];
[str replaceOccurrencesOfString:"&" withString:#"__38__"
options:NSLiteralSearch
range:NSMakeRange(0, [str length])];
You see the pattern!
You can also just use XML entities for these values, e.g. replace & with &.
Thanks for the help everybody, this code actually solved my problem:
for (unichar asciiChar = 1; asciiChar <= 255; asciiChar++) {
NSString *stringWithAsciiChar = [NSString stringWithCharacters:&asciiChar length:1];
if (stringWithAsciiChar == nil) continue;
string = [string stringByReplacingOccurrencesOfString:stringWithAsciiChar withString:[NSString stringWithFormat:#"__%d__", asciiChar]];
}