在此项目的UI端，有一个日期选择器和列表选择器，旨在允许用户选择特定时区的未来时间和日期，以安排通过语音，短信，电子邮件等广播警报。不幸的是，GMT偏移量没有正确调整。例如，2017年6月7日17:33在德国柏林（GMT + 0200）预定的警报实际上是柏林时间02:30的第二天。
2017-06-08 00:33:00 +0200
1。谁会知道什么可能导致这种差异，以及如何 为所有时区纠正？
2。调整所有预定的步骤是必要的 中部夏令时的时间？
Screenshot of New Alert View Controller
在NewAlertTableViewController.m中，此函数更新日期选择器标签：
- (void) updateDateLabel {
NSDate *now = [NSDate date];
NSDate *scheduledDate = self.datePicker.date;
if ([scheduledDate isToday] && scheduledDate.hour <= now.hour && scheduledDate.minute <= now.minute) {
self.dateLabel.text = NSLocalizedString(@"Now", @"label for time an alert is scheduled to be sent");
self.sendButton.title = NSLocalizedString(@"Send Alert", @"button label for sending an alert");
self.alert.sendNow = YES;
} else if ([scheduledDate isToday]) {
self.dateLabel.text = [NSString stringWithFormat: NSLocalizedString(@"Today, %@", @"label for time an alert is scheduled to be sent"), [scheduledDate stringWithDateStyle: NSDateFormatterNoStyle timeStyle: NSDateFormatterShortStyle]];
self.sendButton.title = NSLocalizedString(@"Save Alert", @"button label for saving an alert");
self.alert.sendNow = NO;
} else {
self.dateLabel.text = [scheduledDate stringWithDateStyle: NSDateFormatterShortStyle
timeStyle: NSDateFormatterShortStyle];
self.sendButton.title = NSLocalizedString(@"Save Alert", @"button label for saving an alert");
self.alert.sendNow = NO;
}
self.alert.scheduledDate = scheduledDate;
DDLogInfo(@"Date Picker: %@", scheduledDate);
}
同样在NewAlertTableViewController.m中，我们有这个委托来处理时区选择器视图：
- (void) pickerView: (UIPickerView *)pickerView didSelectRow: (NSInteger)row inComponent: (NSInteger)component {
NSString *timeZone;
NSString *timeZoneCity;
NSDateFormatter *systemTimeZoneFormatter = [NSDateFormatter new];
systemTimeZoneFormatter.timeZone = [NSTimeZone localTimeZone];
systemTimeZoneFormatter.dateFormat = @"Z";
NSString *systemTimeZoneOffset = [systemTimeZoneFormatter stringFromDate: [NSDate date]];
switch (row) {
case 0:
timeZone = (@"GMT%@", systemTimeZoneOffset);
timeZoneCity = @"Device Default";
break;
case 1:
timeZone = @"GMT+02:00";
timeZoneCity = @"Berlin";
break;
case 2:
timeZone = @"GMT+01:00";
timeZoneCity = @"London";
break;
case 3:
timeZone = @"GMT-04:00";
timeZoneCity = @"New York";
break;
case 4:
timeZone = @"GMT-05:00";
timeZoneCity = @"Chicago";
break;
case 5:
timeZone = @"GMT-06:00";
timeZoneCity = @"Denver";
break;
case 6:
timeZone = @"GMT-07:00";
timeZoneCity = @"Los Angeles";
break;
case 7:
timeZone = @"GMT-08:00";
timeZoneCity = @"Anchorage";
break;
case 8:
timeZone = @"GMT-10:00";
timeZoneCity = @"Honolulu";
break;
default:
break;
}
[self updateTimeZone: timeZone];
[[NSUserDefaults standardUserDefaults] setObject: timeZone forKey: @"timeZonePreference"];
DDLogInfo(@"Time Zone Picker: %@, %@", timeZone, timeZoneCity);
_timeZoneLabel.text = timeZoneCity;
}
在NewAlertTableViewController.m中，此函数再次更新时区：
- (void) updateTimeZone: (id)timeZone {
self.now = [NSDate date];
self.calendar = [[NSCalendar alloc] initWithCalendarIdentifier: NSCalendarIdentifierGregorian];
[self.calendar setTimeZone: [NSTimeZone timeZoneWithName: timeZone]];
NSCalendarUnit units = NSCalendarUnitHour;
NSDateComponents *components = [self.calendar components: units fromDate: self.now];
self.hours = (int)[components hour];
self.alert.calendar = self.calendar;
}
在Alert.m中，我们将此字符串作为参数发送到CreateAlert.aspx端点。 理想情况，我们更喜欢将所有字符串调整为中部夏令时（以匹配我们在德克萨斯州休斯顿的服务器）或至少协调世界时（UTC）。
- (NSString *)scheduledDateString { // This method solely uses the scheduledDate
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
dateFormatter.dateFormat = @"yyyy-MM-dd HH:mm:ss Z";
dateFormatter.timeZone = self.calendar.timeZone;
NSString *dateString = [dateFormatter stringFromDate: self.scheduledDate];
DDLogInfo(@"Scheduled Date: %@", dateString);
return dateString;
}
答案 0 :(得分：0)
以下是一些示例代码：
withMargins()要记住的关键是，无论您是在伦敦，纽约，休斯顿，檀香山，东京，柏林等地，NSDate对象都是相同的。唯一的区别在于它的显示方式。
例如：现在，差不多是下午5点。但等等，当你读到这篇文章时，它可能在下午4点左右 !!!怎么可能？好吧，我现在看// User-selected Time Zone city
// using "Europe/Berlin" for this example
NSString *timeZoneName = @"Europe/Berlin";
NSTimeZone *timeZone = [NSTimeZone timeZoneWithName:timeZoneName];
// User-selected Date/Time (from the UIDatePicker)
NSDate *selDate = _datePicker.date;
// Current NSCalendar
NSCalendar *calendar = [NSCalendar currentCalendar];
// get all date components from the user-selected Date/Time
NSDateComponents *localComponents = [calendar components:-1 fromDate:selDate];
// set the Calendar to use the user-selected Time Zone
[calendar setTimeZone: timeZone];
// set the components with the values from localComponents
NSDateComponents *timeZoneComponents = [[NSDateComponents alloc] init];
[timeZoneComponents setYear: [localComponents year]];
[timeZoneComponents setMonth: [localComponents month]];
[timeZoneComponents setDay: [localComponents day]];
[timeZoneComponents setHour: [localComponents hour]];
[timeZoneComponents setMinute: [localComponents minute]];
[timeZoneComponents setSecond: [localComponents second]];
// get a NSDate object based on the user-selected Date/Time and Time Zone
// Note: if you print the default description of this date, it will show UTC value
NSDate *desiredDateTime = [calendar dateFromComponents:timeZoneComponents];
NSLog(@"%@", desiredDateTime);
，我看到＆＃34; 2017-06-07 20:55:56 + 0000＆＃34; - 因为那是＆＃34;绝对＆＃34;日期/时间。
所以，玩这个代码示例...尝试不同的时区（确保你的名字正确）...看看是否一切都有意义。
如果我做得对（我可能在这里犯了一两个错误）......如果你选择6月16日星期五上午10点在你的约会选择器（不管在哪里）在世界上你是），然后运行此代码，最终的[NSDate date];行应该打印：
NSLog()因为UTC比柏林时间早2小时。
答案 1 :(得分：0)
感谢来自 @DonMag 的精明建议，我在家中伸展！现在使用这个新的NewAlertTableViewController.m时区选择器视图委托来获得完美的NSDates：
- (void) pickerView: (UIPickerView *)pickerView didSelectRow: (NSInteger)row inComponent: (NSInteger)component {
NSString *timeZoneName;
NSString *timeZoneLabel;
NSDateFormatter *systemTimeZoneFormatter = [NSDateFormatter new];
systemTimeZoneFormatter.timeZone = [NSTimeZone localTimeZone];
systemTimeZoneFormatter.dateFormat = @"VVVV";
NSString *systemTimeZoneOffset = [systemTimeZoneFormatter stringFromDate: [NSDate date]];
switch (row) {
case 0:
timeZoneName = ("%@", systemTimeZoneOffset);
timeZoneLabel = @"Device Default";
break;
case 1:
timeZoneName = @"Europe/Berlin";
timeZoneLabel = @"Berlin";
break;
case 2:
timeZoneName = @"Europe/London";
timeZoneLabel = @"London";
break;
case 3:
timeZoneName = @"America/New_York";
timeZoneLabel = @"New York";
break;
case 4:
timeZoneName = @"America/Chicago";
timeZoneLabel = @"Chicago";
break;
case 5:
timeZoneName = @"America/Denver";
timeZoneLabel = @"Denver";
break;
case 6:
timeZoneName = @"America/Los_Angeles";
timeZoneLabel = @"Los Angeles";
break;
case 7:
timeZoneName = @"America/Anchorage";
timeZoneLabel = @"Anchorage";
break;
case 8:
timeZoneName = @"Pacific/Honolulu";
timeZoneLabel = @"Honolulu";
break;
default:
break;
}
[self updateTimeZone: timeZoneName];
_timeZoneLabel.text = timeZoneLabel;
NSTimeZone *timeZone = [NSTimeZone timeZoneWithName: timeZoneName];
DDLogInfo(@"Time Zone Picker: %@", timeZoneName);
NSDate *datePickerSelection = _datePicker.date;
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *localComponents = [calendar components: -1 fromDate: datePickerSelection];
[calendar setTimeZone: timeZone];
NSDateComponents *timeZoneComponents = [[NSDateComponents alloc] init];
[timeZoneComponents setYear: [localComponents year]];
[timeZoneComponents setMonth: [localComponents month]];
[timeZoneComponents setDay: [localComponents day]];
[timeZoneComponents setHour: [localComponents hour]];
[timeZoneComponents setMinute: [localComponents minute]];
[timeZoneComponents setSecond: [localComponents second]];
_desiredDateTime = [calendar dateFromComponents: timeZoneComponents];
DDLogInfo(@"Desired Date: %@", _desiredDateTime);
}