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

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); 

请您参考如下方法:

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;