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+--- Thread: Objective-C - Remove last character from string (/Thread-Objective-C-Remove-last-character-from-string)
Objective-C - Remove last character from string - overdared375371 - 07-21-2023
In Objective-C for iOS, how would I remove the last character of a string using a button action?
RE: Objective-C - Remove last character from string - Sirunquieter15 - 07-21-2023
The documentation is your friend, `NSString` supports a call `substringWithRange` that can shorten the string that you have an return the shortened String. You cannot modify an instance of `NSString` it is immutable. If you have an `NSMutableString` is has a method called `deleteCharactersInRange` that can modify the string in place
...
NSRange r;
r.location = 0;
r.size = [mutable length]-1;
NSString* shorted = [stringValue substringWithRange:r];
...
RE: Objective-C - Remove last character from string - leanngnvjlg - 07-21-2023
If it's an NSMutableString (which I would recommend since you're changing it dynamically), you can use:
[myString deleteCharactersInRange:NSMakeRange([myRequestString length]-1, 1)];
RE: Objective-C - Remove last character from string - unacademicmyrugntfcx - 07-21-2023
The solutions given here actually do not take into account multi-byte Unicode characters ("composed characters"), and could result in invalid Unicode strings.
In fact, the iOS header file which contains the declaration of `substringToIndex` contains the following comment:
> Hint: Use with rangeOfComposedCharacterSequencesForRange: to avoid breaking up composed characters
See [how to use `rangeOfComposedCharacterSequenceAtIndex:`][1] to delete the last character correctly.
[1]:
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RE: Objective-C - Remove last character from string - filiatedoc - 07-21-2023
In your controller class, create an action method you will hook the button up to in Interface Builder. Inside that method you can trim your string like this:
<br>
if ([string length] > 0) {
string = [string substringToIndex:[string length] - 1];
} else {
//no characters to delete... attempting to do so will result in a crash
}
<br>
<br><br><br>
_______
If you want a fancy way of doing this in just one line of code you could write it as:
string = [string substringToIndex:string.length-(string.length>0)];
_______
*Explanation of fancy one-line code snippet:
<br><br>
If there is a character to delete (i.e. the length of the string is greater than 0)
<br> `(string.length>0)` returns `1` thus making the code return:
<br> `string = [string substringToIndex:string.length-1];`
<br><br>
If there is NOT a character to delete (i.e. the length of the string is NOT greater than 0)
<br> `(string.length>0)` returns `0` thus making the code return:
<br> `string = [string substringToIndex:string.length-0];`
<br> Which prevents crashes.