ios Objective-C：如何提取字符串的一部分（例如以“#”开头）

Objective-C: How to extract part of a String (e.g. start with '#')

提问by Zhen

I have a string as shown below,

我有一个如下所示的字符串，

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'?

如何仅选择以“#”开头（并以空格结尾）的文本，在本例中为“subString1”和“subString2”？

Note: Question was edited for clarity

注意：为了清楚起见，对问题进行了编辑

回答by ughoavgfhw

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

您可以使用NSScanner来拆分字符串。这段代码将遍历一个字符串并用子字符串填充一个数组。

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:

以下是代码的工作原理：

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 substringto the substringsarray.
6. GOTO 1

1. 最多扫描一个#。如果未找到，则扫描仪将位于字符串的末尾。
2. 如果扫描仪在字符串的末尾，我们就完成了。
3. 扫描 # 字符，使其不在输出中。
4. 最多扫描一个空格，扫描的字符存储在substring. 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。否则它将返回YES。
5. 如果字符被扫描（该方法返回 YES），则添加substring到substrings数组中。
6. 转到 1

回答by Varun Chatterji

[aString substringWithRange:NSMakeRange(13, 10)] 

would give you substring1

会给你 substring1

You can calculate the range using:

您可以使用以下方法计算范围：

NSRange startRange = [aString rangeOfString:@"#"];
NSRange endRange = [original rangeOfString:@"1"];

NSRange searchRange = NSMakeRange(startRange.location , endRange.location);
[aString substringWithRange:searchRange] 

would give you substring1

会给你 substring1

Read more: Position of a character in a NSString or NSMutableString

阅读更多： 字符在 NSString 或 NSMutableString 中的位置

and

和

http://iosdevelopertips.com/cocoa/nsrange-and-nsstring-objects.html

http://iosdevelopertips.com/cocoa/nsrange-and-nsstring-objects.html

回答by Rob Caraway

Pretty simple, easy to understand version avoiding NSRangestuff:

非常简单，易于理解的版本避免使用NSRange：

NSArray * words = [string componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]; 
NSMutableArray * mutableWords = [NSMutableArray new];
for (NSString * word in words){
    if ([word length] > 1 && [word characterAtIndex:0] == '#'){
        NSString * editedWord = [word substringFromIndex:1];
        [mutableWords addObject:editedWord];
    }
}

回答by Brain2000

Assuming that you are looking to find the first string that starts with a pound, and ends with a space, this might work. I don't have XCode in front of me, so forgive me if there's a syntax error or length off by 1 somewhere:

假设您要查找以磅开头并以空格结尾的第一个字符串，这可能会奏效。我面前没有 XCode，所以如果某个地方有语法错误或长度减少 1，请原谅我：

-(NSString *)StartsWithPound:(NSString *)str {
    NSRange range = [str rangeOfString:@"#"];
    if(range.length) {
        NSRange rangeend = [str rangeOfString:@" " options:NSLiteralSearch range:NSMakeRange(range.location,[str length] - range.location - 1)];
        if(rangeend.length) {
            return [str substringWithRange:NSMakeRange(range.location,rangeend.location - range.location)];
        }
        else
        {
            return [str substringFromIndex:range.location];
        }
    }
    else {
        return @"";
    }
}

回答by Krys Jurgowski

Another simple solution:

另一个简单的解决方案：

NSRange hashtag = [aString rangeOfString:@"#"];
NSRange word = [[aString substringFromIndex:hashtag.location] rangeOfString:@" "];
NSString *hashtagWord = [aString substringWithRange:NSMakeRange(hashtag.location, word.location)];

回答by Septronic

This is what I'd do:

这就是我要做的：

NSString *givenStringWithWhatYouNeed = @"What you want to look through";
NSArray *listOfWords = [givenStringWithWhatYouNeed componentsSeparatedByString:@" "];
for (NSString *word in listOfWords) {
    if ([[word substringWithRange:NSMakeRange(0, 1)]isEqualToString:@"#"]) {
        NSString *whatYouWant = [[word componentsSeparatedByString:@"#"]lastObject];
    }
}

Then you can do what you need with the whatYouWantinstances. If you want to know which string it is (if it's the substring 1 or 2), check the index of of wordstring in the listOfWordsarray.

然后，您可以对whatYouWant实例执行所需的操作。如果您想知道它是哪个字符串（如果它是子字符串 1 或 2），请检查数组中word字符串的索引listOfWords。

I hope this helps.

我希望这有帮助。

回答by Enrico Cupellini

A general and simple code to select all the words starting with "#" in a NSString is:

用于选择 NSString 中所有以“#”开头的单词的通用且简单的代码是：

NSString * aString = @"This is the #substring1 and #subString2 ...";
NSMutableArray *selection=@[].mutableCopy;
while ([aString rangeOfString:@"#"].location != NSNotFound)
{
    aString = [aString substringFromIndex:[aString rangeOfString:@"#"].location +1];
    NSString *item=([aString rangeOfString:@" "].location != NSNotFound)?[aString substringToIndex:[aString rangeOfString:@" "].location]:aString;
    [selection addObject:item];
}

if you still need the original string you can do a copy. The inline conditional is used in case your selected item is the last word

如果您仍然需要原始字符串，您可以复制一份。如果您选择的项目是最后一个词，则使用内联条件