Objective-C-从字符串中删除最后一个字符 [英] Objective-C - Remove last character from string

问题描述

在iOS版Objective-C中，如何使用按钮操作删除字符串的最后一个字符?

In Objective-C for iOS, how would I remove the last character of a string using a button action?

推荐答案

在您的控制器类中，创建一个操作方法，您可以将该按钮连接到Interface Builder中.在该方法内，您可以像这样修剪字符串:

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
}

如果您只想用一种精美的方式在一行代码中完成此操作，则可以将其编写为:

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)];

---

*花式单行代码段的说明:

如果有要删除的字符(即字符串的长度大于0)
(string.length>0)返回1从而使代码返回:
string = [string substringToIndex:string.length-1];

如果没有要删除的字符(即字符串的长度不大于0)
(string.length>0)返回0从而使代码返回:
string = [string substringToIndex:string.length-0];
这可以防止崩溃.

---

*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.

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