objective-c - 如何获取包含任何日期的午夜 NSDates？

Question

给定任何 NSDate，我如何获得上一个午夜和下一个午夜的日期？

Answer 1

这非常复杂，但可行:

NSDate *date = ...;
NSUInteger componentFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit;
NSDateComponents *parts = [[NSCalendar currentCalendar] components:componentFlags fromDate:date];
NSDateComponents *midnightComponents = [[NSDateComponents alloc] init];
[midnightComponents setDay:[parts day]];
[midnightComponents setMonth:[parts month]];
[midnightComponents setYear:[parts year]];
NSCalendar *cal = [[NSCalendar currentCalendar];
NSDate *midnight = [cal dateFromComponents:midnightComponents];

NSDateComponents *offsetComponents = [[NSDateComponents alloc] init];
[offsetComponents setDay:1];
NSDate *nextMidnight = [cal dateByAddingComponents:offsetComponents toDate: midnight options:0];

与 .NET 甚至 Java 相比，我认为 Apple 的设计有点过于复杂，但它是易于管理的。