如何复制NSMutableAttributedString

Question

I'm just wondering how I can make a copy of an NSMutableAttributedString . I have a property called text that I'd like to save its contents at a certain point and revert back to it in case something happens. I've tried making a property called textCopy where I can save it to with @property (nonatomic, copy) but I get a runtime error when I do this:

 -[NSConcreteAttributedString insertAttributedString:atIndex:]: unrecognized selector sent to instance.

How would I accomplish this?

Updated with run time error. I'm getting this anytime I set the NSMutableAttributedString to @property (nonatomic, copy) . Not understanding why this wouldn't work, in general the copy paramter doesn't seem to work with NSMutableAttributedString whether I'm using its setter method or not.

Answer 1

The problem is that you've declared the property with the copy attribute, and are presumably using the compiler-generated setter. The compiler-generated setter sends the copy message to the object to make a copy. The copy message makes an immutable copy. That is, it creates an NSAttributedString , not an NSMutableAttributedString .

One way to fix this is to write your own setter that uses mutableCopy , like this if you're using ARC:

- (void)setTextCopy:(NSMutableAttributedString *)text {
    textCopy = [text mutableCopy];
}

or like this if you're using manual reference counting:

- (void)setTextCopy:(NSMutableAttributedString *)text {
    [textCopy release];
    textCopy = [text mutableCopy];
}

Another fix would be to make textCopy be an NSAttributedString instead of an NSMutableAttributedString , and make the rest of your code work with it as an immutable object.