目标C：如何提取部分字符串（例如，以'＃'开头） [英] Objective C: How to extract part of a String (e.g. start with '#')

问题描述

  NSString * aString = @这是＃substring1和＃subString2 I想; 
  

如何只选择以'＃'开头（以空格结尾）的文本，这种情况下'subString1'和'subString2'？

注意：为了清楚起见，编辑了问题

解决方案

您可以使用 NSScanner 将字符串分开。

  NSString * aString = @这是＃substring1和＃subString2我想要; 
 NSMutableArray * substrings = [NSMutableArray new]; 
 NSScanner * scanner = [NSScanner scannerWithString：aString]; 
 [scanner scanUpToString：@＃intoString：nil]; //扫描前面的所有字符＃
 while（！[scanner isAtEnd]）{
 NSString * substring = nil; 
 [scanner scanString：@＃intoString：nil]; //扫描＃字符
 if（[scanner scanUpToString：@intoString：& substring]）{
 //如果紧跟在＃后面的空格将被跳过
 [子字符串addObject：substring]; 
} 
 [scanner scanUpToString：@＃intoString：nil]; //在下一个＃
之前扫描所有字符
 //用子字符串做一些事
 [substrings release]; 
  

以下是代码的工作原理：

1. 扫描到＃。如果找不到，扫描器将位于字符串的末尾。


2. 如果扫描器位于字符串的末尾，我们就完成了。


3. 扫描＃字符，使其不在输出中。
   
4. 扫描一个空格，扫描的字符存储在子。如果＃是最后一个字符，或者后面紧跟一个空格，则该方法将返回NO。
   
5. 如果扫描了字符（方法返回YES），向 substring >子字符串数组。


6. GOTO 1

I have a string as shown below,

NSString * aString = @"This is the #substring1 and #subString2 I want";

How can I select only the text starting with '#' (and ends with a space), in this case 'subString1' and 'subString2'?

Note: Question was edited for clarity

解决方案

You can do this using an NSScanner to split the string up. This code will loop through a string and fill an array with substrings.

NSString * aString = @"This is the #substring1 and #subString2 I want";
NSMutableArray *substrings = [NSMutableArray new];
NSScanner *scanner = [NSScanner scannerWithString:aString];
[scanner scanUpToString:@"#" intoString:nil]; // Scan all characters before #
while(![scanner isAtEnd]) {
    NSString *substring = nil;
    [scanner scanString:@"#" intoString:nil]; // Scan the # character
    if([scanner scanUpToString:@" " intoString:&substring]) {
        // If the space immediately followed the #, this will be skipped
        [substrings addObject:substring];
    }
    [scanner scanUpToString:@"#" intoString:nil]; // Scan all characters before next #
}
// do something with substrings
[substrings release];

Here is how the code works:

1. Scan up to a #. If it isn't found, the scanner will be at the end of the string.
2. If the scanner is at the end of the string, we are done.
3. Scan the # character so that it isn't in the output.
4. Scan up to a space, with the characters that are scanned stored in substring. If either the # was the last character, or was immediately followed by a space, the method will return NO. Otherwise it will return YES.
5. If characters were scanned (the method returned YES), add substring to the substrings array.
6. GOTO 1

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