objective-c - 从 dateFromString 方法的 NSDateFormatter 获取错误的日期？

Question

我正在尝试获取 NSDate来自字符串的对象。我使用休闲代码

NSString *st1=@"4:39 AM";
NSDateFormatter *dateFormatter=[[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"hh:mm a"];
NSDate *dateobj=[dateFormatter dateFromString:st1];
NSLog(@"Date from string 4:39 AM is %@",dateobj);

但它给出了错误的输出，例如

来自字符串 4:39 AM 的日期是 1969-12-31 23:09:00 +0000

获取 NSDate 的确切方法是什么？来自这种类型的字符串的对象。

Answer 1

不要将结果基于 NSLoging NSDate ，因为记录它会给你格林威治标准时间
请引用我对这个问题的回答 NSDateFormatter giving me time 4 hours ahead

例如，如果您想触发 UILocalNotification在凌晨 4:39，您将执行以下操作

NSCalendar* myCalendar = [NSCalendar currentCalendar];
NSDateComponents* components = [myCalendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit 
                                             fromDate:[NSDate date]];
//4:39 Am
[components setHour: 4]; //4 am
[components setMinute: 39];//39 minutes
[components setSecond: 0];// 0 seconds
NSDate *myDate = [myCalendar dateFromComponents:components];

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"MMMM dd, yyyy h:mma"];  
NSString *str = [formatter stringFromDate:myDate];

NSLog(@"date is %@", myDate); //This will log the correct data but in GMT time zone
NSLog(@"date is %@", str); //This will log the correct data

UILocalNotification *notification = [[UILocalNotification alloc] init];
notification.fireDate = myDate;