objective-c - 用于距离的 objective-c 字符串格式化程序

我有一段距离，就像浮游物一样，我正在寻找一种可以很好地为人类读者格式化的方式。理想情况下，我希望它随着m的增大而从m更改为km，并很好地舍入该数字。转换为英里将是一个奖励。我确信很多人都需要其中之一，并且我希望某个地方有一些代码。

这是我想要的格式:

0-100m:47m(作为整数)

100-1000m:325m或320m(四舍五入到最接近的5或10米)

1000-10000m:1.2km(四舍五入到小数点后一位)

10000m +:21公里

如果没有可用的代码，如何编写自己的格式化程序？

谢谢

最佳答案

这些解决方案都无法真正满足我的需求，因此我在这些解决方案的基础上:

#define METERS_TO_FEET  3.2808399
#define METERS_TO_MILES 0.000621371192
#define METERS_CUTOFF   1000
#define FEET_CUTOFF     3281
#define FEET_IN_MILES   5280

- (NSString *)stringWithDistance:(double)distance {
    BOOL isMetric = [[[NSLocale currentLocale] objectForKey:NSLocaleUsesMetricSystem] boolValue];

    NSString *format;

    if (isMetric) {
        if (distance < METERS_CUTOFF) {
            format = @"%@ metres";
        } else {
            format = @"%@ km";
            distance = distance / 1000;
        }
    } else { // assume Imperial / U.S.
        distance = distance * METERS_TO_FEET;
        if (distance < FEET_CUTOFF) {
            format = @"%@ feet";
        } else {
            format = @"%@ miles";
            distance = distance / FEET_IN_MILES;
        }
    }

    return [NSString stringWithFormat:format, [self stringWithDouble:distance]];
}

// Return a string of the number to one decimal place and with commas & periods based on the locale.
- (NSString *)stringWithDouble:(double)value {
    NSNumberFormatter *numberFormatter = [[NSNumberFormatter alloc] init];
    [numberFormatter setLocale:[NSLocale currentLocale]];
    [numberFormatter setNumberStyle:NSNumberFormatterDecimalStyle];
    [numberFormatter setMaximumFractionDigits:1];
    return [numberFormatter stringFromNumber:[NSNumber numberWithDouble:value]];
}

- (void)viewDidLoad {
    [super viewDidLoad];

    double distance = 5434.45;
    NSLog(@"%f meters is %@", distance, [self stringWithDistance:distance]);

    distance = 543.45;
    NSLog(@"%f meters is %@", distance, [self stringWithDistance:distance]);

    distance = 234234.45;
    NSLog(@"%f meters is %@", distance, [self stringWithDistance:distance]);
}

关于objective-c - 用于距离的 objective-c 字符串格式化程序，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/2324125/