NSDateComponents在兩個日期之間獲取日期的日期屬性不正確

Question

我正在使用NSDateComponents和NSCalendar獲取兩個日期之間的日期。

// Get dates between before and after 
NSDateComponents *betweenDateComponents = [calendar components:componentFlags 
                 fromDate:afterDate 
                  toDate:beforeDate 
                 options:0]; 

然後我有一個簡單的循環，是基於組件的天屬性：

for (int i = 1; i < betweenDateComponents.day; ++i) { 

這完美的作品時，我所有的一個月工作了一個星期，或者。如果按星期過濾，則日期屬性日誌記錄爲6.如果按月過濾日期屬性爲29，但由於某種原因，當我按年份過濾時，日期屬性記錄爲29而不是364.

爲什麼當我嘗試與一年的工作時，這一天的財產總是錯誤的？

這裏是我的所有代碼，直到for循環我上面包括：

// Set the date components according to the type of filter we're doing 
    NSCalendar *calendar = [NSCalendar currentCalendar]; 
    NSDateComponents *components = [NSDateComponents new]; 
    if (filterType == CommentFilterTypeWeeklyByDay) { 
     [components setDay:-6]; 
    } else if (filterType == CommentFilterTypeMonthlyByDay) { 
     [components setDay:-29]; 
    } else if (filterType == CommentFilterTypeYearlyByMonth) { 
     [components setDay:-364]; 
    } 

    NSUInteger componentFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit; 

    // Zero out before and after dates 
    NSDate *beforeDate = [NSDate date]; 
    NSDateComponents *zeroComponents = [[NSCalendar currentCalendar] components:componentFlags fromDate:beforeDate]; 
    beforeDate = [calendar dateFromComponents:zeroComponents]; 

    NSDate *afterDate = [calendar dateByAddingComponents:components toDate:beforeDate options:0]; 
    zeroComponents = [[NSCalendar currentCalendar] components:componentFlags fromDate:afterDate]; 
    afterDate = [calendar dateFromComponents:zeroComponents]; 

    NSMutableArray *dates = [NSMutableArray new]; 
    [dates addObject:afterDate]; 

    // Get dates between before and after 
    NSDateComponents *betweenDateComponents = [calendar components:componentFlags 
                  fromDate:afterDate 
                  toDate:beforeDate 
                  options:0]; 
    NSLog(@"%d", betweenDateComponents.day); 

    for (int i = 1; i < betweenDateComponents.day; ++i) { 

Answer 1

因爲你的組件包括：NSYearCalendarUnit和NSMonthCalendarUnit，我懷疑你將不得不使用month和year而不是僅僅day。這些組件是累積的，不是獨立的。

您隨時都可以通過改變得到的天只是數（不管有多少個月或數年都是你日期間），您components：

NSCalendar *calendar = [NSCalendar currentCalendar]; 
NSDateComponents *components = [NSDateComponents new]; 

switch (filterType) { 
    case CommentFilterTypeWeeklyByDay: [components setDay:-6]; break; 
    case CommentFilterTypeMonthlyByDay: [components setDay:-29]; break; 
    case CommentFilterTypeYearlyByMonth: [components setDay:-364]; break; 
    case CommentFilterTypeCustom: [components setDay:-590]; break; 
    default: break; 
} 

NSUInteger componentFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit; 
NSDate *beforeDate = [NSDate date]; 
NSDateComponents *zeroComponents = [[NSCalendar currentCalendar] components:componentFlags fromDate:beforeDate]; 
beforeDate = [calendar dateFromComponents:zeroComponents]; 

NSDate *afterDate = [calendar dateByAddingComponents:components toDate:beforeDate options:0]; 
zeroComponents = [[NSCalendar currentCalendar] components:componentFlags fromDate:afterDate]; 
afterDate = [calendar dateFromComponents:zeroComponents]; 

NSDateComponents *betweenDateComponents = [calendar components:NSDayCalendarUnit 
                 fromDate:afterDate 
                 toDate:beforeDate 
                 options:0]; 

NSLog(@"%d", betweenDateComponents.day); 

的NSLog這裏打印

6爲CommentFilterTypeWeeklyByDay

29爲CommentFilterTypeMonthlyByDay

364爲CommentFilterTypeYearlyByMonth

590爲CommentFilterTypeCustom