我有一个距离作为一个浮动,我正在寻找一种方式来格式很好地为人类读者.理想情况下,我希望它从m变化到km,随着它变大,并且数字很好.转换为里程将是一个奖金.我相信很多人都需要其中的一个,我希望有一些代码在某处浮动.
以下是我想要的格式：
> 0-100m：47m(整数)
> 100-1000m：325m或320m(圆到最近的5或10米)
> 1000-10000m：1.2km(圆形到最接近一个小数位)
> 10000m：21km
如果没有可用的代码,我该怎么写我自己的格式化程序？
谢谢
解决方法
这些解决方案都没有真正满足我正在寻找的东西,所以我建立在它们之上：
#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 %@",[self stringWithDistance:distance]);
distance = 234234.45;
NSLog(@"%f meters is %@",[self stringWithDistance:distance]);
}
