获取当前的iPhone设备时区日期和时间从UTC-5时区日期和时间iPhone应用程序？

Question

在我的iPhone应用程序中，我很难将webservice响应时间转换为当前的设备时间。webservice time in UTC-5 timezone。这款应用在全世界都在使用。因此，我必须将响应时间转换为当前设备时区。这是一个简单的消息应用程序。

当我发送了一个webservice is "2012-07-16 07:33:01".，但是当我从检索时间的时候当我在应用程序中显示时间时，我应该将时间转换为设备的本地时间。我试过了一些方法，但我还不能解决。守则是：

NSDateFormatter *dateFormatter1 = [[NSDateFormatter alloc] init]; 
[dateFormatter1 setDateFormat:@"yyyy-MM-dd HH:mm:ss"]; 
[dateFormatter1 setLocale:[NSLocale currentLocale]];
//[dateFormatter1 setTimeZone:[NSTimeZone timeZoneWithName:@"IST"]];
[dateFormatters setTimeZone:[NSTimeZone systemTimeZone]];
NSDate *date = [dateFormatter1 dateFromString:dateStr];
NSLog(@"date : %@",date);

但是输出日期和时间是2012-07-16 02:03:01 +0000，我已经将这个日期/时间存储在Coredata中，当我使用下面的代码从CoreData检索并隐藏到NSString时，

NSDateFormatter *dateFormatters = [[NSDateFormatter alloc] init];
[dateFormatters setDateFormat:@"dd-MMM-yyyy hh:mm"];
[dateFormatters setDateStyle:NSDateFormatterShortStyle];
[dateFormatters setTimeStyle:NSDateFormatterShortStyle];
[dateFormatters setDoesRelativeDateFormatting:YES];
[dateFormatters setTimeZone:[NSTimeZone systemTimeZone]];  
dateStr = [dateFormatters stringFromDate:dateString];
NSLog(@"DateString : %@", dateStr);

输出日期和时间为"Today 7:33 AM“。应该是"Today 5:05 PM“。谁能救我一天吗？请帮助解决这个问题。提前谢谢。

Answer 1

我已经测试了您的场景，并添加了一些代码供您参考。请测试下面的内容，请让我知道它对你是有用的。

NSString *dateStr = @"2012-07-16 07:33:01";
NSDateFormatter *dateFormatter1 = [[NSDateFormatter alloc] init]; 
[dateFormatter1 setDateFormat:@"yyyy-MM-dd HH:mm:ss"]; 
NSDate *date = [dateFormatter1 dateFromString:dateStr];
NSLog(@"date : %@",date);

NSTimeZone *currentTimeZone = [NSTimeZone localTimeZone];
NSTimeZone *utcTimeZone = [NSTimeZone timeZoneWithAbbreviation:@"UTC"];

NSInteger currentGMTOffset = [currentTimeZone secondsFromGMTForDate:date];
NSInteger gmtOffset = [utcTimeZone secondsFromGMTForDate:date];
NSTimeInterval gmtInterval = currentGMTOffset - gmtOffset;

NSDate *destinationDate = [[[NSDate alloc] initWithTimeInterval:gmtInterval sinceDate:date] autorelease];

NSDateFormatter *dateFormatters = [[NSDateFormatter alloc] init];
[dateFormatters setDateFormat:@"dd-MMM-yyyy hh:mm"];
[dateFormatters setDateStyle:NSDateFormatterShortStyle];
[dateFormatters setTimeStyle:NSDateFormatterShortStyle];
[dateFormatters setDoesRelativeDateFormatting:YES];
[dateFormatters setTimeZone:[NSTimeZone systemTimeZone]];  
dateStr = [dateFormatters stringFromDate: destinationDate];
NSLog(@"DateString : %@", dateStr);

谢谢。

Answer 2

NSDate* currentDate = [NSDate date];

NSTimeZone* CurrentTimeZone = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];
NSTimeZone* SystemTimeZone = [NSTimeZone systemTimeZone];

NSInteger currentGMTOffset = [CurrentTimeZone secondsFromGMTForDate:currentDate];
NSInteger SystemGMTOffset = [SystemTimeZone secondsFromGMTForDate:currentDate];
NSTimeInterval interval = SystemGMTOffset - currentGMTOffset;

NSDate* TodayDate = [[NSDate alloc] initWithTimeInterval:interval sinceDate:currentDate];
NSLog(@"Current time zone Today Date : %@", TodayDate);

Swift 4

var currentDate = Date()
var CurrentTimeZone = NSTimeZone(abbreviation: "GMT")
var SystemTimeZone = NSTimeZone.system as NSTimeZone
var currentGMTOffset: Int? = CurrentTimeZone?.secondsFromGMT(for: currentDate)
var SystemGMTOffset: Int = SystemTimeZone.secondsFromGMT(for: currentDate)
var interval = TimeInterval((SystemGMTOffset - currentGMTOffset!))
var TodayDate = Date(timeInterval: interval, since: currentDate)
print("Current time zone Today Date : \(TodayDate)")

希望它对另一个开发人员有帮助！编码愉快！

Answer 3

希望这次延期会更容易。

Swift 4：UTC/GMT⟺Local (Current/System)

extension Date {

    // Convert local time to UTC (or GMT)
    func toGlobalTime() -> Date {
        let timezone = TimeZone.current
        let seconds = -TimeInterval(timezone.secondsFromGMT(for: self))
        return Date(timeInterval: seconds, since: self)
    }

    // Convert UTC (or GMT) to local time
    func toLocalTime() -> Date {
        let timezone = TimeZone.current
        let seconds = TimeInterval(timezone.secondsFromGMT(for: self))
        return Date(timeInterval: seconds, since: self)
    }

}


// Try it
let utcDate = Date().toGlobalTime()
let localDate = utcDate.toLocalTime()

print("utcDate - (utcDate)")
print("localDate - (localDate)")