Objective-C - Remove last character from string
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)];
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:
if ([string length] > 0) {
string = [string substringToIndex:[string length] - 1];
} else {
//no characters to delete... attempting to do so will result in a crash
}
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:
If there is a character to delete (i.e. the length of the string is greater than 0)
(string.length>0)
returns 1
thus making the code return:
string = [string substringToIndex:string.length-1];
If there is NOT a character to delete (i.e. the length of the string is NOT greater than 0)
(string.length>0)
returns 0
thus making the code return:
string = [string substringToIndex:string.length-0];
Which prevents crashes.
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:
to delete the last character correctly.