NSDate class summary, comprehensive basis, nsdate summary basis

NSDate class summary, comprehensive basis, nsdate summary basis

<Span style = "font-size: 24px;"> <span style = "font-size: 18px;"> // 1. create date object // The NSDate object created will always be zero time zone. If you want to calculate the time zone in GMT, add eight hours NSDate * date = [NSDate date]; NSLog (@ "% @", date); // create the date at this time tomorrow (the time interval is calculated in seconds) NSDate * tomorrow = [NSDate dateWithTimeIntervalSinceNow: 24*60*60]; NSLog (@ "% @", tomorrow); // create the date at the time of yesterday (-indicates that the start date is counted from the current time) NSDate * yesterday = [NSDate dateWithTimeIntervalSinceNow:-24*60*60]; NSLog (@ "% @", yesterday ); // obtain the time interval between two dates (timeInterval is a redefinition of the Double Precision type, so the output time must be % g, and the time price is calculated in seconds) NSTimeInterval timeInterval = [tomorrow timeIntervalSinceDate: yesterday]; NSLog (@ "% g", timeInterval/60/60/24); // compare the morning and evening of a date // (1) compare the earlier dates of the two dates (Return Value Type: NSDate) NSDate * earlerDate = [yesterday earlierDate: tomorrow]; NSLog (@ "% @", earlerDate); // (2) compare the date NSDate * laterDate = [yesterday laterDate: tomorrow]; NSLog (@ "% @", laterDate); // (3) compare two dates (the return value type is Enumeration type, which is to take the first parameter to subtract the value of the second parameter, the enumerated value is-, 1) NSComparisonResult result = [yesterday compare: tomorrow]; NSLog (@ "% ld", result); // time interval exercise: If a fixed time is less than 60 seconds, output "just ", if "60-3600" is output "how many minutes ago", if "3600-3600*24" is output "how many hours ago ", if the number of days before the output is greater than 3600*24, NSDate * date1 = [NSDate date]; NSDate * date2 = [NSDate dateWithTimeIntervalSinceNow: 100]; NSTimeInterval time = [date2 timeIntervalSinceDate: date1]; if (time> 0 & time <= 60) {NSLog (@ "just");} else if (time <= 3600) {NSLog (@ "% d Minutes Ago", (int) (time/60);} else if (time <= 3600*24) {NSLog (@ "% d Hours Ago", (int) (time/60/60);} else {NSLog (@ "% d days ago", (int) (time/60/60/24);} // NSDateFormatter Date Format class // function: convert a date into a string in a certain format ), you can also convert the date format string to the NSDate object NSDate * date3 = [NSDate date]; // create the current date object NSDateFormatter * formatter = [[NSDateFormatter alloc] init]; // create Date Format object [formatter setDateFormat: @ "yyyy-MM-dd HH: mm: SS"]; // set the date format for the object. // specify the date format. // HH indicates the 24-hour format. hh indicates the 12-hour format. // MM indicates the month. mm indicates the minute. // dd indicates the number of days in the month. DD indicates the day of the current year. // ss indicates the number of seconds. // If the year is set to two yy, only the last two digits of the year are displayed. If y is given to another number, the complete year is displayed. // For example, if MM and so on are given two digits, if the month is one digit, the first digit is 0. [formatter setDateStyle: NSDateFormatterFullStyle]; // set the date output style [formatter setTimeStyle: NSDateFormatterFullStyle]; // set the time output style NSString * dateStr = [formatter stringFromDate: date3]; NSLog (@ "% @", dateStr); // convert the date format string to an NSDate object @ "20:08:08" NSString * dateStr1 = @ "2008-08-08 20:08:08 "; // create date formatter NSDateFormatter * formatter1 = [[NSDateFormatter alloc] init]; // set the date format (must be consistent with the date format in the Date Format String ). [formatter1 setDateFormat: @ "yyyy-MM-dd HH: mm: ss"]; // convert the format string to NSData object NSDate * date4 = [formatter1 dateFromString: dateStr1]; NSLog (@ "% @", date4); </span>

Summary of basic biology knowledge in high school (Comprehensive)

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