xcode 如何在objective-c中现有字符串的开头添加一个字符？
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How to add a character at the beginning of an existing string in objective-c?
提问by wackytacky99
How do I add a single character such as a '$' or a '+' at the beginning of an existing string?
如何在现有字符串的开头添加单个字符，例如 ' $' 或 ' +'？
I tried using the appendingString method but that adds the $or +at the end of the string.
我尝试使用 appendString 方法，但是在字符串的末尾添加了$或+。
I know I can always save the $or +in a new string and then append the other string, but I just want to know if there is a better way to do it.
我知道我总是可以将$或保存+在一个新字符串中，然后附加另一个字符串，但我只想知道是否有更好的方法来做到这一点。
Thank you.
谢谢你。
回答by WendiKidd
This is actually very simple:
这其实很简单：
[@"+" stringByAppendingString:existingString];
This should definitely work for you :) And the +will be at the beginning.
这绝对适合您:) 并且+将在开始时。
回答by jscs
Strings aren't mutable. You're creating a new string when you use stringByAppendingString:In order to prepend, you would have to make a mutable version of your existing string and then use insertString:atIndex:like so:
字符串是不可变的。您在使用时正在创建一个新字符串stringByAppendingString:为了预先添加，您必须创建现有字符串的可变版本，然后insertString:atIndex:像这样使用：
[[NSMutableString stringWithString:myString] insertString:@"$" atIndex:0];
Why there isn't a stringByPrependingString:, I don't know.
为什么没有stringByPrependingString:，我不知道。
The best solution is the one you've already mentioned:
最好的解决方案是您已经提到的解决方案：
[@"$" stringByAppendingString:myString];
回答by Ben Trengrove
As long as the string is mutable, i.e. it is an NSMutableString you can use.
只要字符串是可变的，即它是您可以使用的 NSMutableString。
[str insertString:@"$" atIndex:0];
Have a read of the docs here, https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/nsmutablestring_Class/Reference/Reference.html
