Objective-C: 10-NSDate and NSDateFormatter, objective-cnsdate

Objective-C: 10-NSDate and NSDateFormatter, objective-cnsdate

NSDate

NSDate time class, inherited from NSObject, whose object represents a time point

    NSDate *date = [NSDate date];    NSLog(@"date = %@", date);

19:08:00. 624 OCNSDate [2955: 309612] date = 11:08:00 + 0000

Print the displayedGreenwich time-month-day hour: minute: Second + Time Zone

1. Get a method to create a time point from the current time interval.DateWithTimeIntervalSinceNow :( NSTimeInterval)

(NSTimeInterval) is essentially a double data type.

NSDate * date1 = [NSDate dateWithTimeIntervalSinceNow: 8*60*60]; // Add the time difference of 8 hours to the GMT time, obtain NSLog (@ "date1 =%@", date1) at Beijing time );

2015-4 4 19:08:00. 625OCNSDate [2955: 309612] date1 =19:08:00 + 0000

　

Exercise 1: Get the current time tomorrow NSDate * nextDay = [NSDate dateWithTimeIntervalSinceNow: 24*60*60 + 8*60*60]; Exercise 2: obtain the NSDate * nextYear = [NSDate dateWithTimeIntervalSinceNow: 366*24*60*60 + 8*60*60]; NSLog (@ "% @", nextYear) next year );

 

2. Calculate the time interval between the specified time and the current time point. timeIntervalSinceNow

NSTimeInterval interval = nextDay. timeIntervalSinceNow;

NSLog (@ "%. 2f", interval );

　3. Calculate the time interval between the two time points timeIntervalSinceDate:

NSTimeInterval interval2 = [date timeIntervalSinceDate: nextYear];

NSLog (@ "%. 2f", interval2 );

　　TimestampConcept: The time interval between a time point and 1970.1.1. This time is measured in seconds and is called a timestamp.

　　Timestamp method: TimeIntervalSince1970

NSTimeInterval interval3 = [date timeIntervalSince1970];

NSLog (@ "%. 2f", interval3 );

　　Converts a timestamp to a time object. DateWithTimeIntervalSince1970:

NSDate * date2 = [NSDate dateWithTimeIntervalSince1970: 3600];

NSLog (@ "% @", date2 );

　　Get Beijing TimeDateByAddingTimeInterval:

NSDate * date3 = [date dateByAddingTimeInterval: 8*60*60];

NSLog (@ "% @", date3 );

　　Exercise 3: The difference between the current time and a fixed time. If the difference is within 60 seconds, the output is "just". If the difference is between 60 and 60 ~ 3600 seconds, the output is before "xx minutes ~ Within 24*3600, the output time is before "xx hours". If the output time is beyond 24*3600 seconds

　　Fixed timeNSDate * pastDate = [NSDate dateWithTimeIntervalSinceNow:-370]; NSLog (@ "% @", pastDate );
　　Current TimeNSDate * nowDate = [NSDate date];Difference between the fixed time and the current timeNSTimeInterval interval4 = [nowDate timeIntervalSinceDate: pastDate]; NSLog (@ "Time Difference: %. 2f seconds", interval4 );
If (interval4 <= 60) {NSLog (@ "");} else if (interval4 <= 3600) {NSLog (@ "%. f Minutes Ago ", interval4/60 );
} Else if (interval4 <= 24*3600) {NSLog (@ "%. f hours ago ", interval4/3600);} else if (interval4> 24*3600) {NSLog (@" % @ ", pastDate );}

 

 

NSDateFormatter

NSDateFormatter Date Format class, inherited from NSFormatter, mainly used to convert an NSDate object to a certain format and then output it as a string

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

　　1. Set the letter used in the Date Format: y represents the year, M represents the month, d represents the day H Represents the hour m represents the minute, s represents the second

[Formartter setDateFormat: @ "MM: dd, yyyy, HH, mm: ss seconds"]; NSDate * date4 = [NSDate dateWithTimeIntervalSinceNow: 0];

　2. Convert the time object to the set format stringFromDate:

During formatting, the system automatically adds the time interval from the zero time zone.

    NSString *dateString = [formartter stringFromDate:date4];    NSLog(@"%@", dateString);

Exercise: Output date4 in the form of @ "2015"

　　Create a time format Class Object init Method

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

　　SetDateFormat: @ "specific time format"

[MyFormatter setDateFormat: @ "yyyy Year MM Month dd No. HH point mm minute ss seconds"];

　　Use a string to receive the converted time stringFromDate:

NSString * dateString1 = [myFormatter stringFromDate: date4];

NSLog (@ "% @", dateString1 );

　　Converts a time string to an NSDate object.

For example: @ "November 24, 2015" NSDateFormatter * formatter3 = [[NSDateFormatter alloc] init]; [formatter3 setDateFormat: @ "MM dd, yyyy, HH, mm, ss seconds"];Preparation Time stringNSString * dateString3 = @ "November 24, 2015 ";Format a time object using a time stringNSDate * date5 = [formatter3 dateFromString: dateString3];
　　The transferred time is returned to the zero time zone.NSLog (@ "% @", date5 );If you want to get Beijing time, you need to manually add 8 hoursNSDate * date6 = [date5 dateByAddingTimeInterval: 8*60*60]; NSLog (@ "% @", date6 );