问题描述
在iOS 8的NSNumberForamtter上同时使用maximumFractionDigits和maximumSignificantDigits时，这是一个错误吗?
Is this a bug when using maximumFractionDigits and maximumSignificantDigits together on NSNumberForamtter on iOS 8?
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
formatter.maximumFractionDigits = 2;
formatter.maximumSignificantDigits = 3;
NSLog(@"%@", [formatter stringFromNumber:@(0.3333)]); // output 0.333 expected 0.33
如果我仅使用maximumFractionDigits
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
formatter.maximumFractionDigits = 2;
NSLog(@"%@", [formatter stringFromNumber:@(0.3333)]); // output expected .33
推荐答案
这不是错误.从文档中:
It isn't a bug. From the docs:
将数字格式化程序配置为使用有效数字时，它将忽略用于设置整数或小数位的任何最小值或最大值.
When a number formatter is configured to use significant digits, it ignores any minimum or maximum values used to set integer or fraction digits.
注意:如果maximumSignificantDigits或minimumSignificantDigits设置为任何值，则usesSignificantDigits将自动设置为true.这与maximumSignificantDigits和minimumSignificantDigits的文档相反:
Note: If either maximumSignificantDigits or minimumSignificantDigits is set to any value, then usesSignificantDigits is automatically set to true. This contradicts the docs for maximumSignificantDigits and minimumSignificantDigits which says:
您无需将usesSignificantDigits设置为true，它将自身设置为true.
You don't need to set usesSignificantDigits to true, it will set itself to true.
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