Nsdatepicker && NSDate

The NSDate class is used to hold time values, and it provides methods to handle some of the day-to-night comparisons between the seconds-based difference (temporal Interval) operations and dates.

1. The following methods are available for creating or initializing

The class method used to create the NSDate instance has

+ (ID) date;

Return Current time

+ (ID) Datewithtimeintervalsincenow: (nstimeinterval) secs;

Returns the current time base, and then the time after secs seconds

+ (ID) datewithtimeintervalsincereferencedate: (nstimeinterval) secs;

Returns the 2001/01/01 GMT as the benchmark, then secs seconds later

+ (ID) dateWithTimeIntervalSince1970: (nstimeinterval) secs;

Returns the 1970/01/01 GMT as the benchmark, then secs seconds later

+ (ID) distantfuture;

Return a certain day of the future many years later.

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

+ (ID) distantpast;

Return a day many years ago.

For example, if you need a time value that is much longer than the current (now), you can call the method. The test returned 0001/12/31 17:00:00 BC

The instance method used to create the NSDate instance has

-(ID) Addtimeinterval: (nstimeinterval) secs;

Returns the time that is saved in the current instance, and then secs seconds

The instance method used to initialize the NSDate instance has

-(ID) init;

Initialized to the current time. Similar to the Date method

-(ID) initwithtimeintervalsincereferencedate: (nstimeinterval) secs;

Initialized to 2001/01/01 GMT, and then secs seconds later. Similar Datewithtimeintervalsincereferencedate: Method

-(ID) Initwithtimeinterval: (nstimeinterval) secs sincedate: (NSDate *) refdate;

Initialized to Refdate, then secs seconds later.

-(ID) Initwithtimeintervalsincenow: (nstimeinterval) secs;

Initialized to the current time, and then secs seconds later

2. Comparisons between dates are available in the following ways

-(BOOL) Isequaltodate: (NSDate *) otherdate;

Same as Otherdate, return Yes

-(NSDate *) Earlierdate: (NSDate *) anotherdate;

Returns the earlier date compared to the Anotherdate

-(NSDate *) Laterdate: (NSDate *) anotherdate;

Compare with Anotherdate, return to the later date

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

Called when the method is used for sorting:

. When the date value saved by the instance is returned with the anotherdate phase Nsorderedsame

. Returns nsordereddescending when the instance holds a date value that is later than anotherdate

. Returns nsorderedascending when the instance holds a date value earlier than anotherdate

3. The time interval can be retrieved using the following methods

-(Nstimeinterval) Timeintervalsincedate: (NSDate *) refdate;

Returns the time interval between the time the instance was saved and the Refdate, with Refdate as the base time

-(Nstimeinterval) Timeintervalsincenow;

Returns the time between the time that the instance was saved and the current time (now) at the current time (now)

-(Nstimeinterval) timeIntervalSince1970;

Returns the time between the time the instance was saved and 1970/01/01 GMT, with 1970/01/01 GMT as the base time

-(Nstimeinterval) timeintervalsincereferencedate;

Returns the time between the time the instance was saved and 2001/01/01 GMT, with 2001/01/01 GMT as the base time

+ (Nstimeinterval) timeintervalsincereferencedate;

Returns the time interval between the current time (now) and 2001/01/01 GMT, with 2001/01/01 GMT as the base time

4. Representing time as a string

-(NSString *) description;

The time is expressed in YYYY-MM-DD hh:mm:ss±hhmm format.

Where "±hhmm" represents the time zone difference between how many hours and minutes of the existence of GMT. For example, if the time zone is set in Beijing, then "±HHMM" is displayed as "+0800"

Get the current date

NSDate *date = [NSDate Date];

NSLog (@ "date:%@", date);

Get (24 * 60 * 60) that is 24 hours before the date, Datewithtimeintervalsincenow:

NSDate *yesterday = [NSDate datewithtimeintervalsincenow:-(24 * 60 * 60)];

NSLog (@ "yesterday:%@", yesterday);

NSDateFormatter *formatter =[[[nsdateformatter alloc] init] autorelease];

NSDate *date = [NSDate Date];

[Formatter Settimestyle:nsdateformattermediumstyle];

Nscalendar *calendar = [[[Nscalendar alloc] Initwithcalendaridentifier:nsgregoriancalendar] autorelease];

Nsdatecomponents *comps = [[[[Nsdatecomponents alloc] init] autorelease];

Nsinteger unitflags = Nsyearcalendarunit |

Nsmonthcalendarunit |

Nsdaycalendarunit |

Nsweekdaycalendarunit |

Nshourcalendarunit |

Nsminutecalendarunit |

Nssecondcalendarunit;

int week=0;

Comps = [Calendar Components:unitflags fromdate:date];

Int week = [comps weekday];

int year=[comps year];

int month = [Comps month];

int day = [Comps day];

[Formatter Setdatestyle:nsdateformattermediumstyle];

This sets the label with the updated time.

int hour = [Comps hour];

int min = [comps minute];

int sec = [comps second];

NSLog (@ "week%d", week);

NSLog (@ "year%d", year);

NSLog (@ "month%d", month);

NSLog (@ "day%d", day);

NSLog (@ "hour%d", hour);

NSLog (@ "min%d", min);

NSLog (@ "sec%d", sec);

Get milliseconds

NSDateFormatter *dateformatter = [[NSDateFormatter alloc] init];

[Dateformatter Setdatestyle:nsdateformattermediumstyle];

[Dateformatter Settimestyle:nsdateformattershortstyle];

[Dateformatter setdateformat:@ "Hh:mm:ss"]

[Dateformatter setdateformat:@] Yyyy-mm-dd HH:mm:ss. SSS "];

NSLog (@ "date%@", [Dateformatter stringfromdate:[nsdate Date]]);

[Dateformatter release];

Nsdatepicker && NSDate