ios - 如何对NSString中的成分进行排序？例如1/2杯牛奶，1/4勺粉

Question

我在NSArray中将如下成分列表作为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"

我想像下面这样对它们进行排序。

"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，两个结果相同。

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，但我无法以某种方式解决这个问题。

如果有人做过类似的事情，您可以指导我。

提前致谢。

Answer 1

您可以在NSString上定义一个类别以比较数字(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逻辑不是很健壮(它可以识别“三十二”，但不能识别“三十二”)，但是您可以根据需要使用它。或者，您可能会完全拉扯它。