在NSDateFormatter

Question

更改周的第一天爲了讓我用一週的天數：

NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease]; 
NSArray *weekdays = [dateFormatter shortWeekdaySymbols]; 

平日裏給了我與天名稱的數組，但它開始在週日。出於某些原因，我希望此陣列在週一或週日開始，具體取決於設備的本地化設置。

有沒有辦法做到這一點？

Answer 1

您可以從當前語言環境的NSCalendar對象的-firstWeekday方法中獲取當前語言環境的第一個工作日的從1開始的索引。然後你就可以相應地修改你的那一週的名字數組：

// get week day names array 
NSArray *weekdays = self.shortWeekdaySymbols; 

// adjust array depending on which weekday should be first 
NSUInteger firstWeekdayIndex = [NSCalendar currentCalendar].firstWeekday - 1; 
if (firstWeekdayIndex) { 

    NSRange firstRange = NSMakeRange(firstWeekdayIndex, weekdays.count - firstWeekdayIndex); 
    NSRange lastRange = NSMakeRange(0, firstWeekdayIndex); 

    NSArray *firstArray = [weekdays subarrayWithRange:firstRange]; 
    NSArray *lastArray = [weekdays subarrayWithRange:lastRange]; 

    weekdays = [firstArray arrayByAddingObjectsFromArray:lastArray]; 
} 

NSLog(@"%@", weekdays); 

我沒有iPhone的SDK，但據我所知，這些API應該是所有可用的存在和行爲的方式在OS X系統

Answer 2

取得了相同的導致類似用斯威夫特hasseg：

var symbols = dateFormatter.shortWeekdaySymbols as! [String] 
    let firstDayIndex = calendar.firstWeekday - 1 

    if firstDayIndex > 0 { 
     var sub = symbols[0..<firstDayIndex] 
     symbols.removeRange(Range<Int>(start:0, end:firstDayIndex)) 
     symbols += sub 
    } 

Answer 3

for i in 0...6 { 
    let day = Calendar.current.weekdaySymbols[(i + Calendar.current.firstWeekday - 1) % 7] 
    print(day) 
} 

Answer 4

像myexec解決方案，但更通用的，同樣簡潔

let numDays = Calendar.current.weekdaySymbols.count 
let first = Calendar.current.firstWeekday - 1 
let end = first + numDays - 1 

let days = (first...end).map {Calendar.current.weekdaySymbols[$0 % numDays]} 

Answer 5

您需要使用NSCalender以編程方式更改本週的開始日期。

NSCalendar *_calendar; 
_calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian]; 
_calendar.timeZone = [NSTimeZone localTimeZone]; 
[_calendar setFirstWeekday:2];// Sunday == 1, Saturday == 7 
_calendar.locale = [NSLocale currentLocale]; 

    NSDateComponents *dateComponent = [_calendar components:(NSCalendarUnitWeekOfYear | NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear) fromDate:[NSDate date]]; 
    NSDate *now = [NSDate date]; 
    NSDateComponents *comp = [_calendar components:NSCalendarUnitYear fromDate:now]; 
    [comp setWeekOfMonth:dateComponent.weekOfYear]; //Week number. 
    [comp setWeekday:2]; 

    NSDate * weekstartPrev = [_calendar dateFromComponents:comp];