在Swift中,你如何创建一个NSNumberFormatter
来保留小数点后的尾随零(12.000),同时还生成一个适合当前区域设置的数字?
我当前的代码和示例输出:
let formatter = NSNumberFormatter()
formatter.numberStyle = .DecimalStyle
formatter.locale = NSLocale.currentLocale()
formatter.maximumFractionDigits = 10
var doubleNumString = "12.0"
println(formatter.numberFromString(doubleNumString)) //in English it prints 12, want it to print 12.0
var doubleNumString = "12.000"
println(formatter.numberFromString(doubleNumString)) //prints 12, want it to print 12.000
var doubleNumString = "12.125"
println(formatter.numberFromString(doubleNumString)) //prints 12.125 as expected
var doubleNumString = "1234"
println(formatter.numberFromString(doubleNumString)) //prints 1,234 as expected
我已经对它进行了编码,如果字符串以小数结尾("12."
),则它不会使用此格式化程序生成数字,而只是显示数字然后显示十进制(但我需要改进它,因为有些语言从右到左阅读。)
一种解决方案是检查字符串是否包含句点,如果是,请检查其后面的所有数字是否为0,如果是,则不要通过数字格式化程序运行它而只运行int通过格式化程序的值然后追加/前置小数后跟适当的0到数。
有更好/更清洁的解决方案吗?
答案 0 :(得分:2)
如Martin R所述,您可以将minimumFractionDigits
和maximumFractionDigits
设置为相同的数字,这将强制始终显示多个小数位。要知道要显示多少,您需要将小数点后的子字符串带到结尾并计算其元素。要知道所有小数位是否为0,我创建了一个辅助方法,将该子字符串转换为数字,如果它等于0,那么你知道它们都是0。
不幸的是,您需要根据原始字符串编号使用几个不同的NSNumberFormatter
将字符串转换为本地化的数字。因此,如果它确实包含一个小数,并且它后面的所有内容都是0,那么您需要创建一个不同的格式化程序,将字符串转换为数字,然后将该数字转换为字符串,以便根据用户的语言环境显示它。否则,您只需使用原始数字格式化程序。
答案 1 :(得分:-1)
此功能可满足您的要求。通过相同的&来自语言环境(例如en_US)
+ (NSString*) stringForString:(NSString*) string forLocale:(NSString*) toLocaleCode fromLocal:(NSString*) fromLocaleCode {
NSLocale *fromLocale = [[NSLocale alloc] initWithLocaleIdentifier:fromLocaleCode];
NSNumberFormatter *sourceFormatter = [[NSNumberFormatter alloc] init];
[sourceFormatter setNumberStyle:NSNumberFormatterDecimalStyle];
[sourceFormatter setUsesGroupingSeparator:NO];
[sourceFormatter setLocale:fromLocale];
NSNumber *localizedNumber = [sourceFormatter numberFromString:string];
if (!localizedNumber) {
return string;
}
NSLocale *toLocale = [[NSLocale alloc] initWithLocaleIdentifier:toLocaleCode];
NSNumberFormatter *destinationFormatter = [[NSNumberFormatter alloc] init];
[destinationFormatter setNumberStyle:NSNumberFormatterDecimalStyle];
[destinationFormatter setUsesGroupingSeparator:NO];
[destinationFormatter setLocale:toLocale];
NSString *localizedString = [destinationFormatter stringFromNumber:localizedNumber];
//add the zeros which were dropped because of the sourceDecimalString number conversion e.g. 0.20 is converted to 0.2
if (localizedString.length < string.length) {
NSRange rangeOfDecimal = [string rangeOfString:sourceFormatter.decimalSeparator];
if (rangeOfDecimal.location != NSNotFound) {
NSString* sourceDecimalString = [string substringFromIndex:rangeOfDecimal.location];
rangeOfDecimal = [localizedString rangeOfString:destinationFormatter.decimalSeparator];
if (rangeOfDecimal.location != NSNotFound) {
NSString* destinationDecimalString = [localizedString substringFromIndex:rangeOfDecimal.location];
if (destinationDecimalString.length < sourceDecimalString.length) {
int difference = sourceDecimalString.length - destinationDecimalString.length;
int toalDecimalDigits = (destinationDecimalString.length - 1) + difference; //-1 to remove '.'
destinationFormatter.minimumFractionDigits = toalDecimalDigits;
destinationFormatter.maximumFractionDigits = toalDecimalDigits;
localizedString = [destinationFormatter stringFromNumber:localizedNumber];
}
}
else{//this indicates no decimal separator in the return string
int toalDecimalDigits = (sourceDecimalString.length - 1); //-1 to remove '.'
destinationFormatter.minimumFractionDigits = toalDecimalDigits;
destinationFormatter.maximumFractionDigits = toalDecimalDigits;
localizedString = [destinationFormatter stringFromNumber:localizedNumber];
}
}
}
return localizedString;
}