Basic nsdate knowledge

1. The following methods can be used to create or Initialize an instance:

The class methods used to create an nsdate instance include:

+ (ID) date;

Returns the current time.

 

+ (ID) datewithtimeintervalsincenow :( nstimeinterval) secs;

The return value is based on the current time, and the time after secs seconds is passed.

 

+ (ID) datewithtimeintervalsincereferencedate :( nstimeinterval) secs;

The returned time is based on 2001/01/01 GMT, and the time passed by secs seconds.

 

+ (ID) datewithtimeintervalsince1970 :( nstimeinterval) secs;

The return value is based on GMT, and the time after secs seconds is passed.

 

+ (ID) distantfuture;

Returns the day of the future many years later.

For example, if you need a time value that is later than the current time (now), you can call this method. The test returns 4000/12/31 16:00:00

 

+ (ID) distantpast;

Returns a day many years ago.

For example, if you need a time value that is earlier (smaller) than the current time, you can call this method. Test returned 0001/12/31 17:00:00 BC

 

The method used to create an nsdate instance is

-(ID) addtimeinterval :( nstimeinterval) secs;

The returned result is based on the time saved in the current instance, and the time passed by secs seconds

 

The methods used to initialize an nsdate instance include:

-(ID) Init;

Initialize to the current time. Similar to the date Method

 

-(ID) initwithtimeintervalsincereferencedate :( nstimeinterval) secs;

The initialization is based on 2001/01/01 GMT, and the time after secs seconds is passed. Similar to datewithtimeintervalsincereferencedate: Method

 

-(ID) initwithtimeinterval :( nstimeinterval) secs sincedate :( nsdate *) refdate;

Initialized to refdate as the benchmark, and then the time passed by secs seconds

 

-(ID) initwithtimeintervalsincenow :( nstimeinterval) secs;

The initialization is based on the current time, and the time after secs seconds is passed.

 

 

2. The following methods are available for comparison between dates:

-(Bool) is1_todate :( nsdate *) otherdate;

Yes is returned for comparison with otherdate.

 

-(Nsdate *) earlierdate :( nsdate *) anotherdate;

Returns the date earlier than anotherdate.

 

-(Nsdate *) laterdate :( nsdate *) anotherdate;

Returns the date later than anotherdate.

 

-(Nscomparisonresult) Compare :( nsdate *) Other;

This method is called for sorting:

. Nsorderedsame is returned when the date value saved by the instance and anotherdate are the same.

. Nsordereddescending is returned when the date value saved by the instance is later than anotherdate.

. Nsorderedascending is returned when the date value saved by the instance is earlier than anotherdate.

 

 

3. The interval for retrieving data can be as follows:

-(Nstimeinterval) timeintervalsincedate :( nsdate *) refdate;

Returns the time interval between the Instance Storage Time and refdate Based on refdate.

 

-(Nstimeinterval) timeintervalsincenow;

Returns the time interval between the Instance Storage Time and the current time (now) based on the current time (now ).

 

-(Nstimeinterval) timeintervalsince1970;

Return the time interval between the Instance Storage Time and GMT based on January 1, GMT.

 

-(Nstimeinterval) timeintervalsincereferencedate;

Returns the time interval between the Instance Storage Time and the GMT value of 2001/01/01.

 

 

+ (Nstimeinterval) timeintervalsincereferencedate;

Returns the interval between the current time (now) and 2001/01/01 GMT Based on the GMT value of 2001/01/01.

 

 

4. Represent the time as a string

-(Nsstring *) description;

Time is represented in the format of YYYY-MM-DD hh: mm: SS ± hhmm.

"± Hhmm" indicates the number of hours and minutes of time zone difference with GMT. For example, if the time zone is set to Beijing, "± hhmm" is displayed as "+ 0800"