String replacement in Objective-C

Question

How to replace a character is a string in Objective-C?

Solution 1

You could use the method

- (NSString *)stringByReplacingOccurrencesOfString:(NSString *)target 
                                        withString:(NSString *)replacement

...to get a new string with a substring replaced (See NSString documentation for others)

Example use

NSString *str = @"This is a string";

str = [str stringByReplacingOccurrencesOfString:@"string"
                                     withString:@"duck"];

Solution 2

NSString objects are immutable (they can't be changed), but there is a mutable subclass, NSMutableString, that gives you several methods for replacing characters within a string. It's probably your best bet.

Solution 3

If you want multiple string replacement:

NSString *s = @"foo/bar:baz.foo";
NSCharacterSet *doNotWant = [NSCharacterSet characterSetWithCharactersInString:@"/:."];
s = [[s componentsSeparatedByCharactersInSet: doNotWant] componentsJoinedByString: @""];
NSLog(@"%@", s); // => foobarbazfoo

Solution 4

It also posible string replacement with stringByReplacingCharactersInRange:withString:

for (int i = 0; i < card.length - 4; i++) {

    if (![[card substringWithRange:NSMakeRange(i, 1)] isEqual:@" "]) {

        NSRange range = NSMakeRange(i, 1);
        card = [card stringByReplacingCharactersInRange:range withString:@"*"];

    }

} //out: **** **** **** 1234

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Comments

[ele]

I thought the point of having NSString and an NSMutableString subclass was because an instance of NSString is unchangeable. While--like any sane person, I'd rather have ducks than strings any day--the fact that you just overwrote the contents of str just blew my mind.

[Colas]

But I guess the adress of str changed in the process

[Septiadi Agus]

it doesn't change. str now contains a whole new string. stringByReplacingOccurencesOfString does NOT mutate the string. It simply return a new string.

[Jed Fox]

Please use the edit link to explain how this code works and don't just give the code, as an explanation is more likely to help future readers. See also How to Answer. source