Objective C: How to grab a number after a sub string from string

问题

I have a lengthy string as below

Please plan to attend to provide upgrade to existing code

morning meeting to acoomdate bum team members

Meeting Number: 457 231 123

---

To join this meeting

1. go to http://domainname.com
2. enter password

Now i want to grab number after the text "Meeting Number" i.e. 457 231 123

Any help please. thanks

EDIT

Lets say i have a string

NSString *myString = @"Please plan to attend to provide upgrade to existing code morning meeting to acoomdate bum team members  Meeting Number: 457 231 123 ----------------------------------------------------- to join this meeting ------------------------------------------------------  1. go to http://domainname.com 2. enter password"

回答1:

You may use regular expressions to capture the numbers also (assuming that there is only numeric characters and spaces in the result, and there is always the "Meeting Number: " prefix):

NSString *text = @"Please plan to attend to provide upgrade to existing code\nmorning meeting to acoomdate bum team members\nMeeting Number: 457 231 123\nTo join this meeting\n\ngo to http://domainname.com\nenter password";
NSError *error = nil;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"Meeting Number: ([0-9 ]+)" options:NSRegularExpressionCaseInsensitive error:&error];
NSArray *matches = [regex matchesInString:text
                                  options:0
                                    range:NSMakeRange(0, [text length])];
for (NSTextCheckingResult *match in matches) {
    NSRange matchRange = [match rangeAtIndex:1];
    NSString *result = [text substringWithRange:matchRange]; // Here is the result
}

this can be used to parse multiple inputs together since we have a loop here. If the requirements is just to parse one input, replace the code after the declaration of the regex with:

NSTextCheckingResult *match = [regex firstMatchInString:text
                                                options:0
                                                  range:NSMakeRange(0, [text length])];
if (match) {
    NSRange matchRange = [match rangeAtIndex:1];
    NSString *result = [text substringWithRange:matchRange];
}

回答2:

You want NSScanner. It's there specifically for this sort of thing.

NSScanner *scanner = [NSScanner scannerWithString:yourString];
NSString *prefix = @"Meeting number: ";
NSString *numbers;
[scanner scanUpToString:prefix intoString:NULL];
[scanner scanString:prefix intoString:NULL];
[scanner scanUpToCharactersFromSet:[NSCharacterSet newlineCharacterSet] intoString:&numbers];
// numbers now contains the numbers you want.

(This can be trivially adapted to find any number by doing scanUpToCharactersFromSet:[NSCharacterSet decimalDigitCharacterSet] instead of the two lines with the prefix string.)

回答3:

This will do it (with very little generality):

NSRange promptRange = [bigString rangeOfString:@"Meeting Number: "];
NSRange numberRange = NSMakeRange(promptRange.location + promptRange.length, 11);
NSString *answer = [bigString substringWithRange:numberRange];

回答4:

Might be you can use something like -

NSCharacterSet *nonNumberSet = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
int numberValue = [[@"Meeting Number: 457 231 123" stringByTrimmingCharactersInSet:nonNumberSet] intValue];

Edit - For all numbers -

NSCharacterSet *nonNumberSet = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
int numberValue = [[[@"Meeting Number: 457 231 123" componentsSeparatedByCharactersInSet:nonNumberSet] componentsJoinedByString:@""] intValue]; 

回答5:

This should do it, if you want one number:

static int ReadMeetingNumber(NSString * string) {
    // ARC:
    // locate the line
    NSString * const prefix = @"Meeting Number: ";
    NSMutableString * meetingNumberLine = nil;
    for (NSString * line in [string componentsSeparatedByCharactersInSet:[NSCharacterSet newlineCharacterSet]]) {
        if ([line hasPrefix:prefix]) {
            meetingNumberLine = [line mutableCopy];
        }
    }

    if (nil == meetingNumberLine) {
        return nil; 
    }
    // trim and get int value
    [meetingNumberLine deleteCharactersInRange:NSMakeRange(0, prefix.length)];
    [meetingNumberLine replaceOccurrencesOfString:@" " withString:@"" options:0 range:NSMakeRange(0, meetingNumberLine.length)];
    return meetingNumberLine.intValue;
}

---

This should do it, if you want to locate the individual numbers:

// ARC:
// Returns an NSArray of NSNumbers
static NSArray * ReadMeetingNumbers(NSString * string) {
    // locate the line
    NSString * const prefix = @"Meeting Number: ";
    NSMutableString * meetingNumberLine = nil;
    for (NSString * line in [string componentsSeparatedByCharactersInSet:[NSCharacterSet newlineCharacterSet]]) {
        if ([line hasPrefix:prefix]) {
            meetingNumberLine = [line mutableCopy];
        }
    }

    if (nil == meetingNumberLine) {
        return nil; 
    }

    [meetingNumberLine deleteCharactersInRange:NSMakeRange(0, prefix.length)];

    // locate the numbers:
    NSMutableArray * results = [NSMutableArray new];
    for (NSString * at in [meetingNumberLine componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]) {
        const int   intValue = at.intValue;
        if (0 != intValue) {
            [results addObject:[NSNumber numberWithInt:intValue]];
        }
    }
    return [results copy];
}

回答6:

You can accomplish the above task by scanning all the numbers in the above string using the following code.

NSString * inputString = @"Please plan to attend to provide upgrade to existing code morning meeting to acoomdate bum team membersMeeting Number: 457 231 123To join this meeting go tohttp://domainname.comenter password"; // Your input string 
NSString * subStr = [inputString substringWithRange:NSMakeRange([inputString rangeOfString:@"Meeting Number:"].location, 27)];
NSString *number = [[subStr componentsSeparatedByCharactersInSet: [[NSCharacterSet decimalDigitCharacterSet] invertedSet]] componentsJoinedByString:@""]; // Scans all numbers from input string
NSLog(@"%@",number); // Your required output printed in console

回答7:

take into string just like

NSString *str = @"Meeting Number: 457 231 123";

seperated by your string

NSArray *theList = [str componentsSeparatedByString:@":"];
NSString *getStr = [theList objectAtIndex:1];
[getStr stringByReplacingOccurrencesOfString:@" " withString:@""];

来源：https://stackoverflow.com/questions/10291881/objective-c-how-to-grab-a-number-after-a-sub-string-from-string