objective-c - 如何从 Xcode 中的 uipicker 获取所选时区的日期和时间

Question

我正在尝试在标签或文本字段中从 uipicker 显示所选时区的日期和时间我没有任何方法可以解决这个问题，所以请任何人帮助我提前致谢。

SelectedTimeZone= [权重 objectAtIndex:[pickerView selectedRowInComponent:0]]; NSString *selectedzone = SelectedTimeZone;

NSCalendar *gregorian=[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[gregorian setTimeZone:[NSTimeZone timeZoneWithName:selectedzone]];
NSDateComponents *timeZoneComps=[[NSDateComponents alloc] init];

NSDate *date=[gregorian dateFromComponents:timeZoneComps];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateStyle:NSDateFormatterFullStyle];
[formatter setDateFormat:@"dd-MM-yyyy HH:mm:ss "];
NSString *todaysDate= [formatter stringFromDate:[NSDate date]];
zone.text = todaysDate;  I know this is not proper way but i'm new to xcode

Answer 1

[NSDate date] 返回代表当前日期和时间的日期对象，无论您身在何处。NSDate 不受地点或时区的限制。只有一个 NSDate 代表现在或任何其他时刻，而不是每个时区的不同日期对象。因此，您不应尝试在时区之间转换日期。

NSDate *now = [NSDate date];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateStyle:NSDateFormatterShortStyle];
[formatter setTimeStyle:NSDateFormatterShortStyle];
[formatter setTimeZone:[NSTimeZone timeZoneWithName:@"Australia/Sydney"]];
NSLog(@"%@",[formatter stringFromDate:now]); //--> 9/9/11 11:54 PM
[formatter setTimeZone:[NSTimeZone timeZoneWithName:@"Europe/Paris"]];
NSLog(@"%@",[formatter stringFromDate:now]);

或 在此处参考相同的问题

Answer 2

要从 uipicker 获取所选时区的日期和时间，请向格式化程序提供日期，如下所示：

NSDate *now = [NSDate date];
NSCalendar *gregorian=[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[gregorian setTimeZone:[NSTimeZone timeZoneWithName:selectedzone]];

NSDateComponents* timeZoneComps = [gregorian components:NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit|NSHourCalendarUnit|NSMinuteCalendarUnit|NSSecondCalendarUnit|NSTimeZoneCalendarUnit fromDate:now];

NSDate *selectedDate=[gregorian dateFromComponents:timeZoneComps];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateStyle:NSDateFormatterFullStyle];
[formatter setDateFormat:@"dd-MM-yyyy HH:mm:ss "];
NSString *strSelectedDate= [formatter stringFromDate:selectedDate];
zone.text = strSelectedDate;