解析shortstyle格式的时间和日期时NSDateFormatter中的错误

Question

NSDateFormatter *inputFormatter = [[NSDateFormatter alloc] init];
[inputFormatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss"];
NSDate *formatterDate = [inputFormatter dateFromString:@"2009-11-03T21:02:34-08:00"];
[inputFormatter release];
NSDateFormatter *outputFormatter = [[NSDateFormatter alloc] init];
[outputFormatter setDateFormat:@"HH:mm 'on' yyyy/MM/dd"];
[outputFormatter setTimeStyle:NSDateFormatterShortStyle];
[outputFormatter setDateStyle:NSDateFormatterShortStyle];


NSString  *newDateString = [outputFormatter stringFromDate:formatterDate];
NSLog(@"newDateString %@", newDateString);

先输出日期，再输出时间，怎么解决这个问题？

我想以短的样式显示时间，然后显示日期

Answer 1

设置时间和日期样式时，将覆盖手动设置的日期格式。

试试这个：

NSDateFormatter *inputFormatter = [[NSDateFormatter alloc] init];
[inputFormatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss"];
NSDate *formatterDate = [inputFormatter dateFromString:@"2009-11-03T21:02:34-08:00"];
[inputFormatter release];
NSDateFormatter *outputFormatter = [[NSDateFormatter alloc] init];

//[outputFormatter setDateFormat:@"HH:mm 'on' yyyy/MM/dd"];
//[outputFormatter setTimeStyle:NSDateFormatterShortStyle];
//[outputFormatter setDateStyle:NSDateFormatterShortStyle];
//NSString  *newDateString = [outputFormatter stringFromDate:formatterDate];

// format for time only
[outputFormatter setTimeStyle:NSDateFormatterShortStyle];
[outputFormatter setDateStyle:NSDateFormatterNoStyle];

// get time
NSString *newTimeString = [outputFormatter stringFromDate:formatterDate];

// format for date only
[outputFormatter setTimeStyle:NSDateFormatterNoStyle];
[outputFormatter setDateStyle:NSDateFormatterShortStyle];

// get date and format with time
NSString *newDateString = [NSString stringWithFormat:@"%@ on %@", newTimeString, [outputFormatter stringFromDate:formatterDate]];

NSLog(@"newDateString %@", newDateString);

Answer 2

设置timeStyle或dateStyle意味着格式化程序忽略您设置的dateFormat。如果无论用户的区域设置如何，您始终希望日期格式为00:00 on 2009/11/04，则应按如下方式设置区域设置：

NSDateFormatter*outputFormatter = [[[NSDateFormatter alloc] init] autorelease];
NSLocale* locale = [[[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"] autorelease];
[outputFormatter setLocale:locale];
[outputFormatter setDateFormat:@"HH:mm 'on' yyyy/MM/dd"];

NSString* newDateString = [outputFormatter stringFromDate:formatterDate];

请注意，如果您正在处理机器读取的日期(例如ISO8601)，则应始终将区域设置设置为en_US_POSIX，因为某些区域设置会将“hh”转换为“hh”，这可能会产生意想不到的结果。