NSDate简单用法
- (void)viewDidLoad {
[super viewDidLoad];
//获取当前时间
NSDate *now=[NSDate date];
NSLog(@"now:%@",now);//now:2016-01-26 03:03:21 +0000
//转换成当地时间,解决时差问题
NSDate *localNow=[self changeToLocalDate:now];
NSLog(@"localNow:%@",localNow);//localNow:2016-01-26 11:03:21 +0000
//NSDate转NSString(不用考虑时差问题)
NSString *strNow=[self stringFromDate:now format:@"yyyy-MM-dd HH:mm:ss"];
NSLog(@"strNow:%@",strNow);//strNow:2016-01-26 11:03:21
//NSString转NSDate(方法1)
NSString *str1=strNow;
NSDate *date1=[self dateFromString:str1 format:@"yyyy-MM-dd HH:mm:ss"];
NSLog(@"date1:%@",date1);//date1:2016-01-26 11:03:21 +0000
//NSString转NSDate(方法2)
NSDate *date2=[self dateFromStringNew:[NSString stringWithFormat:@"%@ z",str1] format:@"yyyy-MM-dd HH:mm:ss z"];
NSLog(@"date2:%@",date2);//date2:2016-01-26 11:03:21 +0000
}
//NSString转NSDate(方法1)
-(NSDate *)dateFromString:(NSString *)string format:(NSString *)format{
NSTimeZone *timeZone = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];//或UTC
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setTimeZone:timeZone];
[dateFormatter setDateFormat:format];
NSDate *date=[dateFormatter dateFromString:string];
return date;
}
//NSString转NSDate(方法2)
-(NSDate *)dateFromStringNew:(NSString *)string format:(NSString *)format{
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:format];
NSDate *date=[dateFormatter dateFromString:string];
return date;
}
//NSDate转NSString(不用考虑时差问题)
-(NSString *)stringFromDate:(NSDate *)date format:(NSString *)format{
NSDateFormatter *dateFormatter =[[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:format];
NSString *dateString = [dateFormatter stringFromDate:date];
return dateString;
}
//转换成当地时间,解决时差问题
-(NSDate *)changeToLocalDate:(NSDate *)date{
NSTimeZone *zone = [NSTimeZone systemTimeZone];
NSInteger interval = [zone secondsFromGMTForDate: date];
NSDate *localDate = [date dateByAddingTimeInterval: interval];
return localDate;
}
//日期之间比较可用以下方法
/*
- (BOOL)isEqualToDate:(NSDate *)otherDate;
与otherDate比较,相同返回YES
- (NSDate *)earlierDate:(NSDate *)anotherDate;
与anotherDate比较,返回较早的那个日期
- (NSDate *)laterDate:(NSDate *)anotherDate;
与anotherDate比较,返回较晚的那个日期
- (NSComparisonResult)compare:(NSDate *)other;
该方法用于排序时调用:
. 当实例保存的日期值与anotherDate相同时返回NSOrderedSame
. 当实例保存的日期值晚于anotherDate时返回NSOrderedDescending
. 当实例保存的日期值早于anotherDate时返回NSOrderedAscending
*/