iOS：模拟日历

Question

我有这段代码

NSDateComponents *components = [[[NSDateComponents alloc] init] autorelease];
[components setYear:2011];
[components setDay:1];
[components setMonth:7];
NSCalendar *gregorianCalendar = [[[NSCalendar alloc]       initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
NSDate *date = [gregorianCalendar dateFromComponents:components];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"dd"];
NSString *strDate = [dateFormatter stringFromDate: date];

，但现在我想为每月的每一天设置 31 个标签：如何为每个标签添加此组件？

[components setDay:1];

我还希望所有的星期日都是红色的，那么平均 7 天的标签必须是红色的；你能帮助我吗？

Answer 1

循环是您的朋友：

NSDateComponents *components = [[[NSDateComponents alloc] init] autorelease];
[components setYear:2011];
[components setDay:1];
[components setMonth:7];
NSCalendar *gregorianCalendar = [[[NSCalendar alloc]       initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
NSDate *firstDate = [gregorianCalendar dateFromComponents:components];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"dd"];

for (int i = 0; i < 31; i++) {
   NSTimeInterval seconds = 24*60*60 * i;
   NSDate *date = [NSDate dateWithTimeInterval:seconds sinceDate:firstDate];
   NSDateComponents *weekdayComponents = [gregorian components:NSWeekdayCalendarUnit fromDate:date];
   int weekday = [weekdayComponents weekday];
   NSString *strDate = [dateFormatter stringFromDate: date];
   yourLabel.text = strDate;
   yourLabel.textColor = weekday == 1 ? [UIColor redColor : blackColor];
}

请将 yourLabel 变量调整为适当的值。

Answer 2

这就像 @Eiko 的答案，除了在处理夏令时、没有 31 天的月份等时更正确：

NSDateComponents *components = [[[NSDateComponents alloc] init] autorelease];
[components setYear:2011];
[components setMonth:7];
[components setDay:1];

NSCalendar *gregorianCalendar = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
NSDate *startDate = [gregorianCalendar dateFromComponents:components];
NSRange rangeOfDays = [gregorianCalendar rangeOfUnit:NSDayCalendarUnit inUnit:NSMonthCalendarUnit forDate:startDate];

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"dd"];

for (NSInteger i = 1; i <= NSMaxRange(rangeOfDays); ++i) {
  [components setDay:i];
  NSDate *date = [gregorianCalendar dateFromComponents:components];

  yourLabel.text = [dateFormatter stringFromDate: date];

  NSDateComponents *weekdayComponents = [gregorian components:NSWeekdayCalendarUnit fromDate:date];
  int weekday = [weekdayComponents weekday];

  yourLabel.textColor = weekday == 1 ? [UIColor redColor : blackColor];
}

[dateFormatter release];