iOS 可读字符串/日期格式化程序

Question

我正在尝试以可读格式显示 2 个日期的差异。正如您从我下面的代码中看到的那样，有很多 if-else 闭包。是否有任何类型的格式化程序或我的 if-elses 方式是否正确？

NSCalendar *c = [NSCalendar currentCalendar];
NSDateComponents *components = [c components:(NSCalendarUnitMonth | NSCalendarUnitDay)
                                        fromDate:startDate
                                          toDate:endDate
                                         options:0];

NSString *leftTimeStr = @"";
if (components.month == 0) {
    if (components.day == 1) {
        leftTimeStr = @"after 1 day";
    }
    else if (components.day > 1) {
        leftTimeStr = [NSString stringWithFormat:@"after %ld days", (long)components.day];
    }
}
else if (components.month == 1) {
    if (components.day == 0) {
        leftTimeStr = @"after 1 month";
    }
    else if (components.day == 1) {
        leftTimeStr = @"after 1 month 1 day";
    }
    else if (components.day > 1) {
        leftTimeStr = [NSString stringWithFormat:@"after 1 month %ld days", (long)components.day];
    }
}
else if (components.month > 1) {
    if (components.day == 0) {
        leftTimeStr = [NSString stringWithFormat:@"after %ld months", (long)components.month];
    }
    else if (components.day == 1) {
        leftTimeStr = [NSString stringWithFormat:@"after %ld months 1 day", (long)components.month];
    }
    else if (components.day > 1) {
        leftTimeStr = [NSString stringWithFormat:@"after %ld months %ld days", (long)components.month, (long)components.day];
    }
}

结果 leftTimeStr 字符串应该类似于以下之一:

"after 5 months 22 days",
"after 5 months 1 day",
"after 5 months",
"after 1 month 22 days",
...
"after 22 days",
"after 1 day"

Answer 1

为此你可以使用 NSDateComponentsFormatter .

NSDateComponentsFormatter *formatter = [[NSDateComponentsFormatter alloc] init];
[formatter setAllowedUnits:NSCalendarUnitMonth | NSCalendarUnitDay];
formatter.maximumUnitCount = 2;
formatter.unitsStyle = NSDateComponentsFormatterUnitsStyleFull;
NSString *difference = [formatter stringFromDate:startDate toDate:endDate];