如何对 NSString 中的成分进行排序？前任。 1/2 杯牛奶，1/4 勺粉

Question

我在 NSArray 中有如下成分列表作为 NSString 对象。

"1/2 Cup Milk",
"125 grams Cashew",
"2 green onions",
"1/4 Cup Sugar",
"1/6 Spoon Salt",
"3/2 XYZ",
"One cup water",
"Almond oil"

我想按如下方式对它们进行排序。

"1/6 Spoon Salt",
"1/4 Cup Sugar",
"1/2 Cup Milk",
"3/2 XYZ",
"2 green onions",
"125 grams Cashew",
"Almond oil",
"One cup water",

尝试 1： 使用 localizedStandardCompare 和 NSNumericSearch 进行排序，结果相同。

结果：

"1/2 Cup Milk",
"1/4 Cup Sugar",
"1/6 Spoon Salt",
"2 green onions",
"3/2 XYZ",
"125 grams Cashew",
"Almond oil",
"One cup water"

我知道这是可能的，但不知何故我无法弄清楚。

有谁做过类似的可以指导一下。

提前致谢。

Answer 1

您可以在 NSString 上定义一个类别来比较数字（包括分数）：

@interface NSString (Number)
- (NSNumber * _Nullable)numberValue;
- (NSComparisonResult)compareNumber:(NSString *)string;
@end

@implementation NSString (Number)

- (NSNumber *)numberValue {
    NSError *error;
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"^\s*(\d+)\s*/\s*(\d+)" options:0 error:&error];
    NSAssert(regex, @"%@", error.localizedDescription);

    NSTextCheckingResult *match = [regex firstMatchInString:self options:0 range:NSMakeRange(0, self.length)];
    if (match) {
        float numerator = [[self substringWithRange:[match rangeAtIndex:1]] floatValue];
        float denominator = [[self substringWithRange:[match rangeAtIndex:2]] floatValue];
        return denominator ? @(numerator / denominator) : nil;
    }

    regex = [NSRegularExpression regularExpressionWithPattern:@"^\s*(\d+)" options:0 error:&error];
    match = [regex firstMatchInString:self options:0 range:NSMakeRange(0, self.length)];
    if (match) {
        return @([self floatValue]);
    }

    // if you don't want it to recognize spelt out numbers, comment the following bit of code

    regex = [NSRegularExpression regularExpressionWithPattern:@"^\s*(\S+)" options:0 error:&error];
    match = [regex firstMatchInString:self options:0 range:NSMakeRange(0, self.length)];
    if (match) {
        NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
        formatter.numberStyle = NSNumberFormatterSpellOutStyle;
        return [formatter numberFromString:[[self substringWithRange:[match rangeAtIndex:1]] lowercaseString]];
    }

    return nil;
}

- (NSComparisonResult)compareNumber:(NSString *)string {
    NSNumber *number1 = [self numberValue];
    NSNumber *number2 = [string numberValue];

    if (number1 && !number2) {
        return NSOrderedAscending;
    }

    if (number2 && !number1) {
        return NSOrderedDescending;
    }

    if (number1 && number2) {
        NSComparisonResult numericComparison = [number1 compare:number2];
        if (numericComparison != NSOrderedSame) {
            return numericComparison;
        }
    }

    return [self caseInsensitiveCompare:string];
}

@end

然后您可以像这样对成分进行排序：

NSArray *ingredients = @[@"1/2 Cup Milk",
                         @"125 grams Cashew",
                         @"2 green onions",
                         @"1/4 Cup Sugar",
                         @"1/6 Spoon Salt",
                         @"3/2 XYZ",
                         @"One cup water",
                         @"Almond oil"];

NSArray *sorted = [ingredients sortedArrayUsingComparator:^NSComparisonResult(NSString  * _Nonnull obj1, NSString  * _Nonnull obj2) {
    return [obj1 compareNumber:obj2];
}];

产生：

"1/6 Spoon Salt",
"1/4 Cup Sugar",
"1/2 Cup Milk",
"One cup water",
"3/2 XYZ",
"2 green onions",
"125 grams Cashew",
"Almond oil"

我必须承认，拼写数字的 NSNumberFormatter 逻辑不可靠（它识别 "Thirty-Two"，但不识别 "Thirty Two"），但如果您可以使用它想。或者你可以完全拉动它。

Answer 2

看起来 Rob post 在我忙着写自己的答案时写了他的好答案。既然我花了时间，我也可以 post 我的。它们相似又不同。

我也从 NSString 的扩展开始：

@interface NSString (NumberSort)

- (nullable NSNumber *)leadingNumber;

@end

@implementation NSString (NumberSort)

- (nullable NSNumber *)leadingNumber {
    if (self.length < 1) return nil;

    // See if the string starts with a digit
    unichar first = [self characterAtIndex:0];
    if ([[NSCharacterSet decimalDigitCharacterSet] characterIsMember:first]) {
        // It does so now get the first word (number)
        NSString *numStr = self;
        NSRange spaceRange = [self rangeOfString:@" "];
        if (spaceRange.location != NSNotFound) {
            numStr = [self substringToIndex:spaceRange.location];
        }

        // Now see if the leading number is actually a fraction
        NSRange slashRange = [numStr rangeOfString:@"/"];
        if (slashRange.location != NSNotFound) {
            // It's a fraction. Compute its value
            NSString *numeratorStr = [[numStr substringToIndex:slashRange.location] stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
            NSString *denominatorStr = [[numStr substringFromIndex:slashRange.location + slashRange.length] stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];

            NSNumberFormatter *fmt = [[NSNumberFormatter alloc] init];
            fmt.numberStyle = NSNumberFormatterDecimalStyle;
            NSNumber *numerator = [fmt numberFromString:numeratorStr];
            NSNumber *denominator = [fmt numberFromString:denominatorStr];
            if (numerator && denominator) {
                return @([numerator doubleValue] / [denominator doubleValue]);
            }
        } else {
            // Not a fraction, convert number string to number
            NSNumberFormatter *fmt = [[NSNumberFormatter alloc] init];
            fmt.numberStyle = NSNumberFormatterDecimalStyle;
            NSNumber *num = [fmt numberFromString:numStr];

            return num;
        }
    } else {
        // See if string starts with spelled out number
        NSString *numStr = self;
        NSRange spaceRange = [self rangeOfString:@" "];
        if (spaceRange.location != NSNotFound) {
            numStr = [self substringToIndex:spaceRange.location];
        }

        NSNumberFormatter *fmt = [[NSNumberFormatter alloc] init];
        fmt.numberStyle = NSNumberFormatterSpellOutStyle;
        NSNumber *num = [fmt numberFromString:[numStr lowercaseString]];

        return num;
    }

    return nil;
}

@end

然后我使用了一个简单的比较器块来处理数组：

NSArray *ingrediants = @[
    @"1/2 Cup Milk",
    @"125 grams Cashew",
    @"2 green onions",
    @"1/4 Cup Sugar",
    @"1/6 Spoon Salt",
    @"3/2 XYZ",
    @"One cup water",
    @"Almond oil"
];

NSArray *sorted = [ingrediants sortedArrayUsingComparator:^NSComparisonResult(NSString * _Nonnull str1, NSString * _Nonnull str2) {
    NSNumber *num1 = [str1 leadingNumber];
    NSNumber *num2 = [str2 leadingNumber];

    if (num1) {
        if (num2) {
            return [num1 compare:num2];
        } else {
            return NSOrderedAscending;
        }
    } else {
        if (num2) {
            return NSOrderedDescending;
        } else {
            return [str1 compare:str2 options:NSCaseInsensitiveSearch];
        }
    }
}];

NSLog(@"Ordered: %@", sorted);

输出：

Ordered: (
    "1/6 Spoon Salt",
    "1/4 Cup Sugar",
    "1/2 Cup Milk",
    "One cup water",
    "3/2 XYZ",
    "2 green onions",
    "125 grams Cashew",
    "Almond oil"
)

我的代码在处理拼写数字时遇到了类似的问题。我的代码按原样只处理单字数字。如果需要，处理多字拼写数字不会花费太多时间。

我的代码还要求任何分数都不能有空格。同样，稍加努力就可以解决此限制。

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