ios - NSCFCalendar dateFromComponents : components cannot be nil

Question

执行以下代码后

NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *expiryDateComponents = [calendar components:(NSCalendarUnitEra|NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay) fromDate:aDate];

你得到以下非崩溃异常

*** -[__NSCFCalendar dateFromComponents:]: components cannot be nil
Future exception.
A few of these errors are going to be reported with this complaint, then further violations will simply be ignored.

Answer 1

tl;dr 确保 fromDate 参数不是 nil。

解释:

NSCalendar 不知道如何处理当你给它一个 nil NSDate 的情况。 API 会向您发出警告，而不是抛出崩溃异常。请注意，此行为可能会发生变化，并可能在未来因 API 更改而导致崩溃。