Objective-C:如何提取字符串的一部分(例如，以“#"开头) [英] Objective-C: How to extract part of a String (e.g. start with '#')

问题描述

我有一个字符串，如下所示，

I have a string as shown below,

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

如何仅选择以'#'开头(以空格结尾)的文本，在这种情况下为'subString1'和'subString2'?

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

注意:为清楚起见，对问题进行了编辑

Note: Question was edited for clarity

推荐答案

您可以使用NSScanner 来拆分字符串.这段代码将遍历字符串，并用子字符串填充数组.

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];

以下是代码的工作方式:

Here is how the code works:

1. 最多扫描#个.如果找不到，则扫描程序将位于字符串的末尾.
2. 如果扫描仪位于字符串的末尾，则说明已完成.
3. 扫描#字符，使其不在输出中.
4. 扫描到一个空格，扫描的字符存储在substring中.如果#是最后一个字符，或者紧随其后是空格，则该方法将返回NO.否则它将返回是".
5. 如果已扫描字符(该方法返回YES)，则将substring添加到substrings数组中.
6. GOTO 1

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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