从Cocoa Touch中的字符串修剪空格的最好方法是什么？ [英] What's the best way to trim whitespace from a string in Cocoa Touch?

问题描述

我想要确定来自用户输入（UITextField）的字符串值是否为空白，如果它不是nil。检查 [textField.text isEqualToString：] 是不够的，因为我想避免任何空白/空格输入（比如说几个空格字符）。

似乎有一个良好的解决方案，我的特定问题的指示在此StOv帖子。

像这样，但我怀疑有（或应该）是一个更好的方法：

  NSString * strResult; 
 NSScanner * scanner = [NSScanner scannerWithString：textField.text]; 
 BOOL hasValidChars = [scanner scanUpToCharactersFromSet：[NSCharacterSet whitespaceAndNewlineCharacterSet] 
 intoString：& strResult]; 
 
 //如果hasValidChars == YES，我们有非空白字符集合到strResult中
  

这显然只适用于我的特定情况，即使那样，如果第一个字符是一个空格，但是我想要的数据，它会失败。所以，我意识到我有点被宠坏了Ruby，但是必须有一个尝试和真正的成语修剪字符串在Cocoa。

Aaa和答案已经在那里，我的道歉：

NSString的 -stringByTrimmingCharactersInSet： p>

返回通过从接收者的两端移除
所创建的新字符串
给定的
中包含的字符字符集。

我仍然很好奇，如果有人有其他/首选的方法。

解决方案

你使用的是whitespaceAndNewlineCharacterSet，很好。但是，而不是使用scanUpToCharactersFromSet，为什么不使用stringByTrimmingCharactersInSet？像这样...

  strResult = [strResult stringByTrimmingCharactersInSet：[NSCharacterSet whitespaceAndNewlineCharacterSet]]; 
  

编辑：没有意识到你已经找到stringByTrimmingCharactersInSet，直到我发布了这个。

I'm looking to determine whether a string value from a user input (UITextField) is "blank" if it's not nil. Checking if [textField.text isEqualToString:""] isn't quite enough because I want to avoid any blank/whitespace input (like say a few space characters).

There does seem to be an indication of a good solution for my particular problem in this StOv post.

Basically it goes something like this, but I suspect there has to (or ought to) be a better way:

NSString *strResult;
NSScanner* scanner = [NSScanner scannerWithString:textField.text];
BOOL hasValidChars = [scanner scanUpToCharactersFromSet:[NSCharacterSet whitespaceAndNewlineCharacterSet] 
                                             intoString:&strResult];

// if hasValidChars == YES, we've got nonwhite space chars collected into strResult

This clearly only works for my particular circumstance, and even then it would fail if the first character was a space but the data I wanted followed. So, I realize I've been a little spoiled by Ruby, but there must be a tried and true idiom for trimming strings in Cocoa.

Aaaand the answer is already out there, my apologies:

NSString's -stringByTrimmingCharactersInSet: would do it:

Returns a new string made by removing from both ends of the receiver characters contained in a given character set.

I'm still curious to hear if anybody has other/preferred ways of doing this.

解决方案

You're using whitespaceAndNewlineCharacterSet, good. But instead of using scanUpToCharactersFromSet, why not use stringByTrimmingCharactersInSet? Something like this...

strResult = [strResult stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

EDIT: Didn't realize you already found stringByTrimmingCharactersInSet until after I posted this.

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