1. 通過(guò)isnumber自帶函數(shù)進(jìn)行數(shù)字計(jì)數(shù)
2. 使用正則表達(dá)式進(jìn)行字符串篩選計(jì)數(shù)

一、isnumber函數(shù)

• 獲得字符串中的數(shù)字個(gè)數(shù), isnumber提供了判斷字符為數(shù)字的機(jī)制

- (NSInteger)numberCount {
    NSInteger count = 0;
    for (NSInteger i = 0; i < self.length; ++i) {
        if (isnumber([self characterAtIndex:i])) {
            //  isnumber提供了判斷字符為數(shù)字的機(jī)制
            count++;
        }
    }
    return count;
}

• 獲得僅包含數(shù)字的字符串

- (NSString *)numberString {
    NSMutableString *string = [NSMutableString string];
    for (NSInteger i = 0; i < self.length; ++i) {
        if (isnumber([self characterAtIndex:i])) {
            [string appendFormat:@"%c", [self characterAtIndex:i]];
        }
    }
    return string;
}

二、正則表達(dá)式

- (NSInteger)countByRegex {
    //  根據(jù)需要篩選字母、數(shù)字選定篩選語(yǔ)句
    NSString *numberRegexStr = @"[0-9]";
//    NSString *symbolRegexStr = @"[a-zA-Z]";
    
    NSRegularExpression *regularExpression = [[NSRegularExpression alloc] initWithPattern:numberRegexStr
                                                                                  options:NSRegularExpressionCaseInsensitive
                                                                                    error:nil];
    NSArray *resultArray = [regularExpression matchesInString:self
                                                      options:0
                                                        range:NSMakeRange(0, self.length)];
    return resultArray.count;
}

只想日后回頭看看來(lái)時(shí)的路，能發(fā)現(xiàn)自己并不是一無(wú)所有。