Replace a character at a certain index in NSString

问题:

I'm looking for a way to replace a character at a certain index of a NSString.

For example: myString = @"******";

I want to replace the 3rd " * " with an "A", so that the string looks like this: myString = @"**A***";

How can I achieve this?

Thanks in advance

回答1:

Try with this:

NSString *str = @"*******";
str = [str stringByReplacingCharactersInRange:NSMakeRange(3, 1) withString:@"A"];
NSLog(@"%@",str);

回答2:

There are really two options;

Since NSString is read-only, you need to call mutableCopy on the NSString to get an NSMutableString that can actually be changed, then call replaceCharactersInRange:withString: on the NSMutableString to replace the characters in it. This is more efficient if you want to change the string more than once.

There is also a stringByReplacingCharactersInRange:withString: method on NSString that returns a new NSString with the characters replaced. This may be more efficient for a single change, but requires you to create a new NSString for each replacement.

回答3:

Try this sample method

-(NSString *)string:(NSString*)string ByReplacingACharacterAtIndex:(int)i byCharacter:(NSString*)StringContainingAChar{

    return [string stringByReplacingCharactersInRange:NSMakeRange(i, 1) withString:StringContainingAChar];

}

if your string is "testing" and you want first character "t" should be replaced with "*" than call method

[self string:yourString ByReplacingACharacterAtIndex:0 byCharacter:@"*"]

Run and Go

回答4:

If you don't mind using a little C, use something like this:

char *str = (char *)[myString UTF8String];
str[2] = 'A';
myString = [NSString stringWithUTF8String:str];

Of course you should be absolutely sure that myString has at least 3 characters before doing this. Other than that, it's a very fast and efficient way to do something like this.

回答5:

My contribution with a swift extension from the response :

extension NSString{

    func replacingACharacterAtIndex(pIndex : Int, pChar : Character) -> NSString{

        return self.stringByReplacingCharactersInRange(NSRange(location: pIndex, length: 1), withString: String(pChar))
    }
}